@book {Wojcik2016783, title = {Metal oxide nanoparticle engineering for printed electrochemical applications}, series = {Handbook of Nanoelectrochemistry: Electrochemical Synthesis Methods, Properties, and Characterization Techniques}, year = {2016}, note = {

cited By 0

}, pages = {783-818}, abstract = {

Engineering procedures governing the selection or development of printable nanostructured metal oxide nanoparticles for chromic, photovoltaic, photocatalytic, sensing, electrolyte-gated TFTs, and power storage applications are established in this chapter. The main focus is given on how to perform the material selection and formulation of printable dispersion in order to develop functional films for electrochemical applications. This chapter is divided into four main parts. Firstly, a brief introduction on electrochemically active nanocrystalline metal oxide films developed via printing techniques is given. This is followed by the description of the film morphology, structure, and required functionality. A theoretical approach to understand the impact of size and shape of nanoparticles on an ink formulation and electrochemical performance being the subject of the third section provides a greater control over the material selection. We attempt to describe these properties and show that for a given material, geometry and size of the nanoparticles have a major influence on the electrochemical reactivity and response time. This gives the ability to tune the performance of the film simply by varying the morphology of incorporated nanostructures. This section is completed by the recommendations on each major step of an ink formulation, together with imposed critical constraints concerning the fluid control. Finally, the performance of the ink-jetprinted dual-phase electrochromic films is discussed as a case study. By providing such a rather systematic survey, we aim to stress the importance of proper design strategy that would result in both improved physicochemical properties of nanoparticle-loaded inks and enhanced electrochemical performance of printed functional films. {\textcopyright} Springer International Publishing Switzerland 2016.

}, doi = {10.1007/978-3-319-15266-0_24}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957028422\&partnerID=40\&md5=aea6f7e156e066b58fafc973712ac046}, author = {Wojcik, P.J., Pereira, L., Martins, R., Fortunato, E.} } @book {Fortunato2010141, title = {Oxide Semiconductors: From Materials to Devices}, series = {Transparent Electronics: From Synthesis to Applications}, year = {2010}, note = {

cited By 0

}, pages = {141-183}, abstract = {n/a}, doi = {10.1002/9780470710609.ch6}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84886125295\&partnerID=40\&md5=a7401b058ea5131fae3dd3307dc9b44e}, author = {Fortunato, E., Barquinha, P., Gon{\c c}alves, G., Pereira, L., Martins, R.} } @book {Barquinha2012, title = {Transparent Oxide Electronics: From Materials to Devices}, series = {Transparent Oxide Electronics: From Materials to Devices}, year = {2012}, note = {

cited By 51

}, abstract = {

Transparent electronics is emerging as one of the most promising technologies for the next generation of electronic products, away from the traditional silicon technology. It is essential for touch display panels, solar cells, LEDs and antistatic coatings. The book describes the concept of transparent electronics, passive and active oxide semiconductors, multicomponent dielectrics and their importance for a new era of novel electronic materials and products. This is followed by a short history of transistors, and how oxides have revolutionized this field. It concludes with a glance at low-cost, disposable and lightweight devices for the next generation of ergonomic and functional discrete devices. Chapters cover: Properties and applications of n-type oxide semiconductors P-type conductors and semiconductors, including copper oxide and tin monoxide Low-temperature processed dielectrics n and p-type thin film transistors (TFTs) - structure, physics and brief history Paper electronics - Paper transistors, paper memories and paper batteries Applications of oxide TFTs - transparent circuits, active matrices for displays and biosensors Written by a team of renowned world experts, Transparent Oxide Electronics: From Materials to Devices gives an overview of the world of transparent electronics, and showcases groundbreaking work on paper transistors. {\textcopyright} 2012 John Wiley \& Sons, Ltd.

}, doi = {10.1002/9781119966999}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84891583994\&partnerID=40\&md5=fe9ed20cdf99e6005a360805485977ad}, author = {Barquinha, P., Martins, R., Pereira, L., Fortunato, E.} } @conference {Vieira1994571, title = {a-Si:H optical speed detector based on the flying spot technique}, booktitle = {Conference Record of the IEEE Photovoltaic Specialists Conference}, volume = {1}, year = {1994}, note = {

cited By 0

}, pages = {571-574}, abstract = {

We have developed in the past a transient technique called Flying Spot Technique (FST)[1], based on the lateral photoeffect. It allows to determine the ambipolar diffusion length and the effective lifetime of the photogenerated carriers, once the light spot velocity and geometry of the structure are known. We propose to apply this technique backwards in order to detect the path and velocity of an object that is moving toward a light source direction. The light back reflected is analyzed by a p.i.n structure measuring the transient transverse photovoltage which is dependent on the object movement (position and velocity). Details concerning material characterization and device geometry will be presented.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028717248\&partnerID=40\&md5=b8d9654e9404beed1040c9483c257eec}, author = {Vieira, M., Fantoni, A., Macarico, A., Soares, F., Martins, R.} } @conference {Vieira1994741, title = {AD-layer for spatial control of light induced degradation on pin devices}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {336}, year = {1994}, note = {

cited By 0

}, pages = {741-746}, abstract = {

In this work we report experimental results on light induced metastability of a-Si: H p.i.n. devices with different microscopic/macroscopic structures and we discuss them in terms of improved stability through spatial control of charged defects grown during light exposure. By placing a thin (few A) intrinsic layer (i) between both p/i and i/n a-Si: H interfaces we are able to reduce the effective degradation rate through spatial modification of the electric field profile in the device. The electronic transport and the stability changes that accompany the change in microstructure (R) and hydrogen content (CH) of the i- and i'-layer, were monitored throughout the entire light induced degradation process and compared with the corresponding μT product (for both carriers) inferred through steady state photoconductivity and Flying Spot Technique (FST) measurements. Results show that the degradation rate is a function of CH and R of both layers and can be correlated with the density of microvoids and di-hydride bonding. Since the i'-layers have a higher CH bonded mainly as SiF2 radicals (R≈0.4), they act as an hindrance to the growth of the defect, in the active region, generating "gettering centers" whose localisation and density are tailored in such a way that they will control spatially the electric field profile during light exposure. Preliminary results show improvements in film{\textquoteright}s stability when the interfacial layer is included. So future progress toward more stable and efficient a-Si: H solar cells will depend on a careful engineering design of the devices. {\textcopyright} 1994 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897710585\&partnerID=40\&md5=bb60a26fffd91aa7597c21b320760679}, author = {Vieira, M., Fantoni, A., Fortunato, E., Lavareda, G., Martins, R.} } @conference {Fortunato2007371, title = {Advanced materials for the next generation of thin film transistors}, booktitle = {IDMC 2007 - International Display Manufacturing Conference and FPD Expo - Proceedings}, year = {2007}, note = {

cited By 1

}, pages = {371-373}, abstract = {

Staggered bottom gate transparent thin film transistors (TTFTs) have been produced by rf magnetron sputtering at room temperature, using amorphous indium-zinc-oxide (IZO) semiconductor, for the channel as well as for the drain and source regions. The obtained TTFTs operate in the enhancement mode with threshold voltages of 2.4 V, saturation mobility of 22.7 cm2/Vs, gate voltage swing of 0.44 V/dec and an ON/OFF current ratio of 7{\texttimes}10 7. The high performances presented by these TTFTs produced at room temperature, make these TFTs a promising candidate for flexible, wearable, disposable portable electronics as well as battery-powered applications.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-56049103340\&partnerID=40\&md5=7b06b5582006e90cd0e382768565e106}, author = {Fortunato, E., Barquinha, P., Pereira, L., Gon{\c c}alves, G., Martins, R.} } @conference {Zhang2005679, title = {Amorphous silicon based p-i-i-n structure for color sensor}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {862}, year = {2005}, note = {

cited By 0

}, pages = {679-683}, abstract = {

This work deals with the study of the role of the film thickness and composition on the color selectivity of the collecting spectrum of glass/ZnO:Ga/p-a-Si1-xCx:H/ a-Si1-x C x:H /a-Si:H/n-a-Si:H/Al photoelectronic detectors produced in a single chamber plasma enhanced chemical vapor deposition (PECVD) system. The cross contaminations were minimized by a rotate-cover substrate holder system. The devices can detect the blue illumination at small reverse bias and detect red illumination at large reverse bias. The role of the process parameters, especially the thickness of the p-type and intrinsic a-Si1-x C x:H, and the intrinsic a-Si:H layers on the device performances were studied in detail aiming to achieve a better detectivity. {\textcopyright} 2005 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-30644478525\&partnerID=40\&md5=6ebba0a3e556d7edb947ab66332b9847}, author = {Zhang, S., Raniero, L., Fortunato, E., Pereira, L., {\'A}guas, H., Ferreira, I., Martins, R.} } @conference {Martins1984778, title = {ANALYSIS OF A NEW PRODUCTION TECHNIQUE FOR AMORPHOUS SILICON SOLAR CELLS.}, booktitle = {Commission of the European Communities, (Report) EUR}, year = {1984}, note = {

cited By 0

}, pages = {778-782}, abstract = {

This new production technique is based on the growth of a-Si films on a reactor where gas decomposition promoted by a capacitively coupled r. f. power system takes place in a chamber separated from that where amorphous films are deposited under the action of an electromagnetic static field. Using this method, we shall reduce films contamination caused by the residual gas desorbed from reactor walls. At the same time, there is a reduction plasma ion and electron damages on the deposited films. The main species impinging upon our substrates will be mainly composed of long life radicals with high mobilities and high diffusion rates, which will give origin to a random silicon network free of long poly-silane chains.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021655867\&partnerID=40\&md5=a9ed57ada367049ba6f12e184a305fb4}, author = {Martins, R., Guimaraes, L., Carvalho, N., Andrade, A.M., Corgnier, S.L.L., Sanematsu, M.S.} } @conference {Martins2011, title = {Away from silicon era: The paper electronics}, booktitle = {Proceedings of SPIE - The International Society for Optical Engineering}, volume = {7940}, year = {2011}, note = {

cited By 5

}, abstract = {

Today there is a strong interest in the scientific and industrial community concerning the use of biopolymers for electronic applications, mainly driven by low-cost and disposable applications. Adding to this interest, we must recognize the importance of the wireless auto sustained and low energy consumption electronics dream. This dream can be fulfilled by cellulose paper, the lightest and the cheapest known substrate material, as well as the Earth{\textquoteright}s major biopolymer and of tremendous global economic importance. The recent developments of oxide thin film transistors and in particular the production of paper transistors at room temperature had contributed, as a first step, for the development of disposable, low cost and flexible electronic devices. To fulfil the wireless demand, it is necessary to prove the concept of self powered devices. In the case of paper electronics, this implies demonstrating the idea of self regenerated thin film paper batteries and its integration with other electronic components. Here we demonstrate this possibility by actuating the gate of paper transistors by paper batteries. We found that when a sheet of cellulose paper is covered in both faces with thin layers of opposite electrochemical potential materials, a voltage appears between both electrodes - paper battery, which is also self-regenerated. The value of the potential depends upon the materials used for anode and cathode. An open circuit voltage of 0.5V and a short-circuit current density of 1μA/cm2 were obtained in the simplest structure produced (Cu/paper/Al). For actuating the gate of the paper transistor, seven paper batteries were integrated in the same substrate in series, supplying a voltage of 3.4V. This allows proper ON/OFF control of the paper transistor. Apart from that transparent conductive oxides can be also used as cathode/anode materials allowing so the production of thin film batteries with transparent electrodes compatible with flexible, invisible, self powered and wireless electronics. {\textcopyright} 2011 SPIE.

}, doi = {10.1117/12.879520}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-80051884757\&partnerID=40\&md5=165d73bb19cd7ccf9498fe260d0d426f}, author = {Martins, R., Br{\'a}s, B., Ferreira, I., Pereira, L., Barquinha, P., Correia, N., Costa, R., Busani, T., Gon{\c c}alves, A., Pimentel, A.} } @conference {Bahubalindruni2016, title = {Basic analog and digital circuits with a-IGZO TFTs}, booktitle = {2016 13th International Conference on Synthesis, Modeling, Analysis and Simulation Methods and Applications to Circuit Design, SMACD 2016}, year = {2016}, note = {

cited By 0

}, abstract = {

This paper presents the characterization of fundamental analog and digital circuits with a-IGZO TFTs from measurements performed at normal ambient. The fundamental blocks considered in this work include digital logic gates, a low-power single stage high-gain amplifier with capcacitive bootstrapping and a level shifter/buffer. These circuits are important functional blocks in analog/Mixed signal IC design with oxide TFTs. Being fabricated at low temperature (\< 200 {\textdegree}C), they can find potential applications in low-cost large-area flexible systems. {\textcopyright} 2016 IEEE.

}, doi = {10.1109/SMACD.2016.7520741}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983792051\&partnerID=40\&md5=f8a3c20eb16c629992b28ad27937beea}, author = {Bahubalindruni, P.G.a , Tavares, V.c , Barquinha, P.b , Martins, R.b , Fortunato, E.b} } @conference {Bahubalindruni2012261, title = {Basic analog circuits with a-GIZO thin-film transistors: Modeling and simulation}, booktitle = {2012 International Conference on Synthesis, Modeling, Analysis and Simulation Methods and Applications to Circuit Design, SMACD 2012}, year = {2012}, note = {

cited By 4

}, pages = {261-264}, abstract = {

This paper addresses a modeling and simulation methodology for analog circuit design with amorphous-GIZO thin-film transistors (TFTs). To reach an effective circuit design flow, with commercially available tools, a TFT model has been first developed with an artificial neural network (ANN). Multilayer perceptron with backpropagation algorithm has been adopted to model the static behavior of the TFT devices, for different aspect ratios. The model was then implemented in Verilog-A, to allow a quick instantiation in circuit. Simulations using Cadence Spectre are performed to validate the model. On a second phase, simulation results of basic analog circuits, with this ANN model, are verified against the actual functional results, namely an adder, subtractor, and current mirror circuit. Results demonstrate not only the ANN model accuracy and compatibility with dc and transient analysis, but also show the a-GIZO TFT capability to perform analog operations. {\textcopyright} 2012 IEEE.

}, doi = {10.1109/SMACD.2012.6339389}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84870576283\&partnerID=40\&md5=a1062f6a54ec6909e9b8599ac8532601}, author = {Bahubalindruni, G.a , Tavares, V.G.a , Barquinha, P.b , Duarte, C.a , Martins, R.b , Fortunato, E.b , De Oliveira, P.G.a} } @conference {Fantoni1997765, title = {Bidimensional numerical analysis of a μc-Si:H P-I-N photodiode under local illumination}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {467}, year = {1997}, note = {

cited By 3

}, pages = {765-770}, abstract = {

The behaviour of a microcrystalline p-i-n junction locally illuminated with monochromatic radiation (incident power of 50 mW/cm2) is analysed by means of numerical experiences. The model used for the two-dimensional analysis of the transport properties of a μc-Si:H p-i-n photo-detector is based on the simultaneous solution of the continuity equations for holes and electrons together with the Poisson{\textquoteright}s equation. The solution is found on a rectangular domain, taking into account the dimension perpendicular to the junction plane and one on the parallel plane. The lateral effects occurring within the structure, due to the non-uniformity of the illumination, are outlined. The results we present show that the potential profile has a linear variation from the illuminated to the dark neutral region. The lateral components of the electric field and of the current density vectors reveal to be mainly localised inside the doped layers.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031371628\&partnerID=40\&md5=9b80cfb219fa09a98958008b420f12b4}, author = {Fantoni, A., Vieira, M., Martins, R.} } @conference {Pereira2007529, title = {Characterization of nickel induced crystallized silicon by spectroscopic ellipsometry}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {910}, year = {2007}, note = {

cited By 0

}, pages = {529-534}, abstract = {

In this work Spectroscopic Ellipsometry (SE) was used to study metal induced crystallization (MIC) on amorphous silicon films in order to analyze the influence of different annealing conditions on their structural properties. The variation of the metal thickness has shown to be determinant on the time needed to full crystallize silicon films. Films of 100 nm thickness crystallize after 2h at 500{\textdegree}C using 1 nm of Ni deposited on it. When reducing the average metal thickness down to 0.05 nm the same silicon film will need almost 10 hours to be totally crystallized. Using a new approach on the modelling procedure of the SE data we show to be possible to determine the Ni remaining inside the crystallized films. The method consists in using Ni as reference on the Bruggeman Effective Medium Approximation (BEMA) layer that will simulated the optical response of the crystallized silicon. Silicon samples and metal layers with different thicknesses were analyzed and this new method has shown to be sensible to changes on the initial metal/silicon ratio. The nickel distribution inside the silicon layers was independently measured by Rutherford Backscattering Spectroscopy (RBS) to check the data obtained from the proposed approach. {\textcopyright} 2006 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34249933331\&partnerID=40\&md5=1d93c70019d9d2d75cce44cd8a87e4a2}, author = {Pereira, L.a , Aguas, H.a , Beckers, M.b , Martins, R.M.S.b , Fortunato, E.a , Martins, R.a} } @conference {Fortunate2003225, title = {Characterization of transparent and conductive ZnO:Ga thin films produced by rf sputtering at room temperature}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {763}, year = {2003}, note = {

cited By 1

}, pages = {225-230}, abstract = {

Gallium-doped zinc oxide films were prepared by rf magnetron sputtering at room temperature as a function of the substrate-target distance. The best results were obtained for a distance of 10 cm, where a resistivity as low as 2.7{\texttimes}10-4 Ωcm, a Hall mobility of 18 cm2/Vs and a carrier concentration of 1.3{\texttimes}1021 cm-3 were achieved. The films are polycrystalline presenting a strong crystallographic c-axis orientation (002) perpendicular to the substrate. The films present an overall transmittance in the visible part of the spectra of about 85 \%, in average. The low resistivity, accomplished with a high growth rate deposited at RT, enables the deposition of these films onto polymeric substrates for flexible applications.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0344927758\&partnerID=40\&md5=055b8c8c399cdc3fb026eb8e0d96d4cb}, author = {Fortunate, E., Assun{\c c}{\~a}o, V., Marques, A., Ferreira, I., {\'A}guas, H., Pereira, L., Martins, R.} } @conference {Fortunato2001, title = {Characterization of zinc oxide thin films deposited by rf magnetron sputtering on Mylar substrates}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {666}, year = {2001}, note = {

cited By 0

}, pages = {F3211-F3216}, abstract = {

Aluminium doped zinc oxide thin films (ZnO:Al) have been deposited on polyester (Mylar type D, 100 μm thickness) substrates at room temperature by r.f. magnetron sputtering. The structural, morphological, optical and electrical properties of the deposited films have been studied. The samples are polycrystalline with a hexagonal wurtzite structure and a strong crystallographic c-axis orientation (002) perpendicular to the substrate surface. The ZnO:Al thin films with 85\% transmittance in the visible and infra-red region and a resistivity as low as 3.6{\texttimes}10-2 Ωcm have been obtained, as deposited. The obtained results are comparable to those ones obtained on glass substrates, opening a new field of low cost, light weight, small volume, flexible and unbreakable large area optoelectronic devices.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035557080\&partnerID=40\&md5=e5bb83d60ab8a46ca3330e25cf7a97c3}, author = {Fortunato, E., Nunes, P., Marques, A., Costa, D., {\'A}guas, H., Ferreira, I., Costa, M.E.V., Martins, R.} } @conference {Ullaha2015144, title = {A combination of solution synthesis \& solution combustion synthesis for highly conducting and transparent Aluminum Zinc Oxide thin films}, booktitle = {IEEE-NANO 2015 - 15th International Conference on Nanotechnology}, year = {2015}, note = {

cited By 0

}, pages = {144-147}, abstract = {

Aluminum Zinc Oxide has been extensively investigated as a cheap alternative to transparent conducting tin oxide films for electronic and optoelectronic applications. Thin films of Aluminum Zinc Oxide have been developed successfully through a combination of solution combustion synthesis and solution synthesis. Zn(NO3)3{\textperiodcentered}6H2O as metal source was dissolved in 2-methoxyethanol as solvent through combustion synthesis with Urea as fuel while dopant source of AlCl3{\textperiodcentered}6H2O was mixed separately in solvent to avoid aluminum oxide formation in the films. Precursor solutions were obtained mixing Zn \& Al separate solutions in 9:1, 8:2, and 7:3 ratios respectively with oxide, fuel and dopant concentrations of 0.5, 0.25, 0.1, and 0.05 M. The film stacks have been prepared through spin-coating with heating at 400{\textdegree}C for 10 minutes after each deposition to remove residuals and evaporate solvents. Thermal annealing in oven at 600{\textdegree}C for 1 hour followed by rapid thermal annealing at 500{\textdegree}C \& 600{\textdegree}C first in vacuum and then in N2-5\%H2 environment respectively for 10 minutes each reduced the resistivity of film stacks. Film stack with 10 layers for an average thickness of 0.5μm gave the best Hall Effect resistivity of 3.2 {\texttimes} 10-2 -cm in the case of 0.5M solution with Zn:Al mixing ratio of 9:1 for RTA annealings at 600{\textdegree}C with an average total transparency of 80 \% in the wavelength range of 400-1200 nm. The results show a clear trend that increasing the amount of ingredients resistivity could further be decreased. {\textcopyright} 2015 IEEE.

}, doi = {10.1109/NANO.2015.7388919}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964317903\&partnerID=40\&md5=b9fb7450b85556faab21fe9840f67e27}, author = {Ullaha, S.a , De Matteis, F.a , Branquinho, R.b , Fortunato, E.b , Martins, R.c , Davoli, I.d} } @conference {Vieira1994575, title = {Comparison of diffusion length measurements from the flying spot technique and the photocarrier grating method in amorphous thin films}, booktitle = {Conference Record of the IEEE Photovoltaic Specialists Conference}, volume = {1}, year = {1994}, note = {

cited By 0

}, pages = {575-578}, abstract = {

Using the Flying Spot Technique (FST) we have studied minority carrier transport parallel and perpendicular to the surface of amorphous silicon films (a-Si:H). To reduce slow transients due to charge redistribution in low resistivity regions during the measurement we have applied a strong homogeneously absorbed bias light. The defect density was estimated from CPM measurements. The steady-state photocarrier grating technique (SSPG) is a 1-dimensional approach. However, the modulation depth of the carrier profile is also dependent on film surface properties, like surface recombination velocity. Both methods yield comparable diffusion lengths when applied to a-Si:H.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028693517\&partnerID=40\&md5=39d158bdfc02d8faa4f58313c721c7b1}, author = {Vieira, M., Fantoni, A., Martins, R., Koynov, S., Wang, F., Grebner, S., Schwarz, R.} } @conference {Martins1996807, title = {Correlation between electrical-optical and structural properties of microcrystalline silicon N type films}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {420}, year = {1996}, note = {

cited By 2

}, pages = {807-812}, abstract = {

Wide band gap microcrystalline silicon films have aroused considerable interest since they combine some electro-optical advantages of amorphous and crystalline materials highly important to produce electro-optical devices such as TFTs and solar cells. In this paper we present results concerning the electro-optical characteristics of highly transparent and conductive n-type μc-Si based films. Here, emphasis is given to the production of n-type μc-films with optical gaps of 2.3 eV and dark conductivity{\textquoteright}s of 6.5 Scm-1.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030409864\&partnerID=40\&md5=76a5b34db3f3f585fc91b25605396272}, author = {Martins, R., Macarico, A., Ferreira, I., Nunes, R., Bicho, A., Fortunato, E.} } @conference {{\'A}guas2000, title = {Correlation between surface/interface states and the performance of MIS structures}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {609}, year = {2000}, note = {

cited By 1

}, pages = {A1211-A1216}, abstract = {

In order to understand the kinetics of formation of interface/surface states and its correlation on the final device performance, a preliminary study was performed on MIS structures, before and after surface oxidation/passivation, using different oxidation techniques and oxides: thermal (in air), chemical (in H2O2) and oxygen plasma. The devices used in this work are based on a glass/Cr/a-Si:H(n+)/a-Si:H(i)/SiOx/Pd structures, where the amorphous silicon intrinsic layer (i a-Si:H) with a photosensitivity of 107 was deposited by a modified plasma enhanced chemical vapour deposition (PECVD) triode system. The electrical properties of a-Si:H MIS structures were investigated by measuring their diode current-voltage characteristics in the dark and under illumination as well as the spectral response, as a function of the various oxidation techniques. Infrared spectroscopy and spectroscopic ellipsometry were used as a complementary tool to characterise the oxidised surface.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034429903\&partnerID=40\&md5=a63686e5ad2f45910209b1afc6c6c11c}, author = {{\'A}guas, H.M.B., Fortunato, E.M.C., Cabrita, A.M., Silva, V., Tonello, P.M.N., Martins, R.F.P.} } @conference {{\'A}guas2003217, title = {Correlation between the Tunnelling Oxide and I-V Curves of MIS Photodiodes}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {762}, year = {2003}, note = {

cited By 0

}, pages = {217-222}, abstract = {

In this work we present results of a study performed on MIS diodes with the following structure: substrate (glass) / Cr (2000{\r A}) / a-Si:H n + (400{\r A}) / a-Si:H i (5500{\r A}) / oxide (0-40{\r A}) / Au (100{\r A}) to determine the influence of the oxide passivation layer grown by different techniques on the electrical performance of MIS devices. The results achieved show that the diodes with oxides grown using hydrogen peroxide present higher rectification factor (2{\texttimes}106) and signal to noise (S/N) ratio (1{\texttimes}107 at -1V) than the diodes with oxides obtained by the evaporation of SiO2, or by the chemical deposition of SiO 2 by plasma of HMDSO (hexamethyldisiloxane), but in the case of deposited oxides, the breakdown voltage is higher, 30V instead of 3-10 V for grown oxides. The ideal oxide thickness, determined by spectroscopic ellipsometry, is dependent on the method used to grow the oxide layer and is in the range between 6 and 20 {\r A}. The reason for this variation is related to the degree of compactation of the oxide produced, which is not relevant for applications of the diodes in the range of {\textpm} 1V, but is relevant when high breakdown voltages are required.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-1642520701\&partnerID=40\&md5=055730d735e878cf5ad1dcf45472f8d7}, author = {{\'A}guas, H.a , Pereira, L.a , Goullet, A.b , Silva, R.a , Fortunato, E.a , Martins, R.a} } @conference {Malik1998599, title = {Cubic to hexagonal phase transition in spray deposited tin-doped indium oxide films}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {481}, year = {1998}, note = {

cited By 6

}, pages = {599-605}, abstract = {

This work{\textquoteright}s aim is to report for the first time the cubic to hexagonal phase transition in tin-doped In2O3 films with a Sn/In atomic ratio of 0.03, fabricated at low temperature and normal pressure from alcoholic solution of InCl3 and SnCl4. The performed X-ray diffraction measurements show a difference between crystallographic symmetry of thin (100 nm) and thick (400 nm) films prepared in the same conditions: the structure of thick films can be related to high pressure In2O3 hexagonal system with a preferred orientation of c-axis parallel to the substrate surface, while thin films present a cubic symmetry with columnar (400) grain orientation. Phase transition nature is connected with non-axial tensile deformation of indium oxide grid due to insertion of chlorine ions in the position of two diagonally opposite oxygen vacancies in In2O3 network.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031621627\&partnerID=40\&md5=963f3bdc49b15194bc2526de694bbd54}, author = {Malik, A., Nunes, R., Martins, R.} } @conference {Martins1984146, title = {CURRENT TRANSPORT IN METAL-AMORPHOUS SEMICONDUCTOR RECTIFYING DEVICES. ITS APPLICATIONS TO SOLAR CELLS.}, booktitle = {Commission of the European Communities, (Report) EUR}, year = {1984}, note = {

cited By 0

}, pages = {146-150}, abstract = {

The current transport in metal-amorphous semiconductor barriers is examined by solving the proper Poisson{\textquoteright}s equation and transport equations within the semiconductor{\textquoteright}s space charge region taking into account the role of trap shallow states distribution function. The effect of metal is also included through appropriate boundary conditions of the above solutions. Generalized transport equations will be derived either when thermionic drift-diffusion emission process dominates or when the conduction mechanism is mainly due to drift-diffusion emission. Both situations will be analysed with or without neglecting carriers losses during their collision free path, from which a tractable expression for the current-voltage characteristic will be determined.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0021655871\&partnerID=40\&md5=4c36e680b39f63b5fccf026dc7a5ac32}, author = {Martins, R., Guimaraes, L.} } @conference {Correia2015261, title = {Design of a robust general-purpose low-offset comparator based on IGZO thin-film transistors}, booktitle = {Proceedings - IEEE International Symposium on Circuits and Systems}, volume = {2015-July}, year = {2015}, note = {

cited By 1

}, pages = {261-264}, abstract = {

This paper presents a low-offset comparator based on n-type amorphous indium gallium zinc oxide thin-film transistors (TFTs). An a-Si:H TFT model was adapted to fit the electrical characterization data obtained for these devices. The proposed comparator comprises three pre-amplification stages, a positive-feedback analog latch and a fully dynamic digital latch. Simulation results show that the proposed circuit can work at several tens of kHz, with an accuracy of the order of 10 mV, considering a supply voltage of 10 V and a current consumption of 380 μA. Monte-Carlo simulations exhibit a 1-sigma random offset voltage smaller than 10 mV and 40 mV, respectively, with and without using autozeroing techniques. {\textcopyright} 2015 IEEE.

}, doi = {10.1109/ISCAS.2015.7168620}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84946231727\&partnerID=40\&md5=4908e61a621263db04a683bf967c03d5}, author = {Correia, A.a b , Martins, R.a , Fortunato, E.a , Barquinha, P.a , Goes, J.b} } @conference {Martins1995791, title = {Detection limit of large area 1D thin film position sensitive detectors based in a-Si:H P.I.N. diodes}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {377}, year = {1995}, note = {

cited By 1

}, pages = {791-796}, abstract = {

The aim of this work is to provide the basis for the interpretation of the steady state lateral photoeffect observed in p-i-n a-Si:H 1D Thin Film Position Sensitive Detectors (1D TFPSD). The experimental data recorded in 1D TFPSD devices with different performances are compared with the predicted curves and the obtained correlation{\textquoteright}s discussed.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029491967\&partnerID=40\&md5=32ddc86dd88889183ca7d49c521b0120}, author = {Martins, R., Lavareda, G., Soares, F., Fortunato, E.} } @conference {Martins2004507, title = {Detection limits of a nip a-Si:H linear array position sensitive detector}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {808}, year = {2004}, note = {

cited By 0

}, pages = {507-512}, abstract = {

This paper presents results of the spatial and frequency detection limits of an integrated array of 32 one-dimensional amorphous silicon thin film position sensitive detectors with a nip structure, under continuous and pulsed laser operation conditions. The data obtained show that 0.45{\texttimes}0.06 cm arrays, occupying a total active area of about 1 cm2 have a spatial resolution better than 10 μm (modulation transfer function of about 0.2), with a cut-off frequency of about 6.8 KHz. Besides that, under pulsed laser conditions the device non-linearity has its minimum (about 1.6\%), for a frequency of about 200Hz. Up to the limits of the cut-off frequency, the device non-linearity increases to values above 4\%.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-12844251430\&partnerID=40\&md5=ddb251671da0c27b32c496ec2e7ded20}, author = {Martins, R.a , Costa, D.a , {\'A}guas, H.a , Soares, F.a , Marques, A.b , Ferreira, I.a , Borges, P.b , Fortunato, E.a} } @conference {Fortunato1994646, title = {Effect of different TCO interfaces on the performances presented by hydrogenated amorphous silicon p-i-n solar cells}, booktitle = {Conference Record of the IEEE Photovoltaic Specialists Conference}, volume = {1}, year = {1994}, note = {

cited By 0

}, pages = {646-649}, abstract = {

In this paper we report results concerning the effect of the TCO interface on hydrogenated amorphous silicon (a-Si:H) p-i-n homojunction solar cells. Its correlation with dark current density-voltage (J-V) characteristics and spectral response, before and after while light-soaking degradation, is analysed. From this study, we conclude that the properties and stability of these devices are not only influenced by the a-Si:H film properties, but also by the properties of the transparent conductive electrode and its interface with the a-Si:H layer.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028704495\&partnerID=40\&md5=22f9649e6715814167b70cfcdb5c037c}, author = {Fortunato, Elvira, Carvalho, Carlos N., Bicho, Ana, Martins, Rodrigo} } @conference {Sekhar2012, title = {The effect of Substrate temperature on physical and electrical properties of DC magnetron sputtered (Ta 2O 5) 0.85(TiO 2) 0.15 films}, booktitle = {IOP Conference Series: Materials Science and Engineering}, volume = {34}, number = {1}, year = {2012}, note = {

cited By 1

}, abstract = {

Thin films of (Ta 2O 5) 0.85(TiO 2) 0.15 were deposited on quartz and p-Si substrates by DC reactive magnetron sputtering at different substrate temperatures (T s) in the range 303 - 873 K. The films deposited at 303 0K were in the amorphous and it transformed to crystalline at substrate temperatures >= 573 0K. The crystallite size was increased from 50 nm to 72 nm with the increase of substrate temperature. The surface morphology was significantly influenced with the substrate temperature. After deposition of the (Ta 2O 5) 0.85(TiO 2) 0.15 films on Si, aluminium (Al) electrode was deposited to fabricate metal/oxide/semiconductor (MOS) capacitors with a configuration of Al/(Ta 2O 5) 0.85(TiO 2) 0.15/Si. A low leakage current of 7.7 {\texttimes} 10 -5 A/cm 2 was obtained from the films deposited at 303 K. The leakage current was decreased to 9.3 {\texttimes} 10 -8 A/cm 2 with the increase of substrate temperature owing to structural changes. The conduction mechanism of the Al/(Ta 2O 5) 0.85(TiO 2) 0.15/Si capacitors was analyzed and compared with mechanisms of Poole-Frenkel and Schottky emissions. The optical band gap (E g) was decreased from 4.45 eV to 4.38 eV with the increase in substrate temperature. {\textcopyright} Published under licence by IOP Publishing Ltd.

}, doi = {10.1088/1757-899X/34/1/012009}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84861316135\&partnerID=40\&md5=733a6d32cedb4566584f26cdad9f5505}, author = {Sekhar, M.C.a , Uthanna, S.a , Martins, R.b , Chandra, S.V.J.b , Elangovan, E.b} } @conference {Dirani19901588, title = {Effect of the deposition parameters on the electro optical properties and morphology of microcrystalline hydrogenated silicon alloys}, booktitle = {Conference Record of the IEEE Photovoltaic Specialists Conference}, volume = {2}, year = {1990}, note = {

cited By 0

}, pages = {1588-1590}, abstract = {

Microcrystalline phosphorus-doped hydrogenated silicon alloy films were deposited in a remote plasma CVD (chemical vapor deposition) system. The film properties were studied as a function of RF power density and hydrogen concentration in the reaction gas mixture. The properties of the deposited films are extremely sensitive to the RF power density in the studied range of 250 mW/cm2 to 625 mW/cm2. Very low values of electrical resistivity were obtained. For an RF power density of 500 mW/cm2, ρ = 3 {\texttimes} 10-2 Ω-cm, while ρ = 1.9 {\texttimes} 103 Ω-cm for 625 mW/cm2, indicating the predominance of the amorphous tissue over the microcrystalline phase. High doping efficiencies which can be correlated to large grain size are indicated by the very low values of the activation energy as low as 30 meV for 500 mW/cm2, that were obtained.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025421278\&partnerID=40\&md5=9089f490738d82163ff2b9d413215310}, author = {Dirani, E.A.T., Pereyra, I., Andrade, A.M., Soler, M.A.G., Martins, R.} } @conference {{\'A}guas2005691, title = {Effect of the load resistance in the linearity and sensitivity of MIS position sensitive detectors}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {862}, year = {2005}, note = {

cited By 0

}, pages = {691-696}, abstract = {

It is experimentally known that the linearity and sensitivity of the position sensitive detectors (PSD) are dependent on the resistance of the collecting layer and of the load resistance, mainly if the detection is based on the measurement of the photo-lateral voltage. To determine the value of the load resistance to be used in metal - insulator - semiconductor (MIS) PSDs structures that lead to the maximum value of sensitivity and linearity, we propose an electrical model through which it is able to simulate the proper sensor response and how the load resistance influence the results obtained. This model is valid for PSDs where the resistance of the collecting resistive layer is quite low (<= 500 Ω), leading to a low output impedance. Under these conditions we conclude that the value of the load resistance should be of about 1 kΩ in order to achieve a good compromise between the linearity and the sensitivity of the PSD. This result is in agreement with the set of experiments performed. {\textcopyright} 2005 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-30644460551\&partnerID=40\&md5=92fa1946bf7683647584b45c27b53ff3}, author = {{\'A}guas, H., Pereira, L., Raniero, L., Fortunato, E., Martins, R.} } @conference {Pereyra1985717, title = {ELECTRO-OPTICAL CHARACTERIZATION OF AMORPHOUS SILICON FILMS DEPOSITED IN A TWO CONSECUTIVE DECOMPOSITION AND DEPOSITION CHAMBERS SYSTEM.}, booktitle = {Commission of the European Communities, (Report) EUR}, year = {1985}, note = {

cited By 0

}, pages = {717-721}, abstract = {

Doped and undoped a-Si:H and a-SiC:H films were deposited by R. F. decomposition of silane and silane/methane mixtures respectively, in a two consecutive (decomposition and deposition) chambers glow discharge capacitively coupled system. Their electro-optical properties were extensively investigated through dark conductivity, photoconductivity, spectral response, optical absorption, R. F. transmission spectra, electron spin ressonance and CxV MOS measurements.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022176794\&partnerID=40\&md5=ca20fbf9855ee0ac6978efeb951b8791}, author = {Pereyra, I., Andrade, A.M., Sanematsu, M.S., Martins, R.} } @conference {Fortunate2004231, title = {Enhancement of the electrical properties of ITO deposited on polymeric substrates by using a ZnO buffer layer}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {814}, year = {2004}, note = {

cited By 1

}, pages = {231-236}, abstract = {

In this paper we present the effect of the insertion of a non-doped nanocrystalline zinc oxide/buffer layer on the electrical, optical and structural properties of indium tin oxide produced at room temperature by radio frequency plasma enhanced reactive thermal evaporation on polymeric substrates. The electrical resistivity of the ITO films is reduced by more than two orders of magnitude (4.5{\texttimes}10-1 to 2.9{\texttimes}10-3 Ωcm). From the Hall effect measurements it is observed that the large decrease associated to the electrical resistivity, is due to the increase associated to the Hall mobility. Concerning the optical properties no effect was observed, being the transmittance in the visible and near the infra red region always higher than 80\%.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-12844261631\&partnerID=40\&md5=a375424ae6af6249a0c8362af2f6d57a}, author = {Fortunate, E., Gon{\c c}alves, A., De Carvalho, C.N., Pimentel, A., Lavareda, G., Marques, A., Martins, R.} } @conference {Topic1996171, title = {Examination of 1-D position sensitive detector performance through analysis of front contact heterojunction}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {420}, year = {1996}, note = {

cited By 1

}, pages = {171-176}, abstract = {

The influence of different TCOs (SnO2 and ITO) on the photoelectrical properties of 1-D position sensitive detectors based on p-i-n structures was studied. A strong cross-contamination in the p-layer and contamination in the i-layer reduce the quality of the device. Numerical analysis of TCO/p-i-n structure also revealed a strong increase in defect states at the p-layer surface which can be attributed to the reduction of TCO. ITO seems to be less appropriate for a front TCO, although the spectral response of the p-i-n structure under reverse bias is not significantly affected by the conditions at the TCO/p heterojunction.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030407615\&partnerID=40\&md5=f5bf3e782d665b0f96430226a7b25ae4}, author = {Topic, M., Smole, F., Furlan, J., Fortunato, E., Martins, R.} } @conference {Martins2010, title = {Floating gate memory paper transistor}, booktitle = {Proceedings of SPIE - The International Society for Optical Engineering}, volume = {7603}, year = {2010}, note = {

cited By 1

}, abstract = {

Reported herein is a nonvolatile n-type floating gate memory paper field-effect transistor, emphasizing the role of the paper structure and properties on the device performance recorded such as in the high capacitance per unit area at low frequencies (\>2.5 μFcm-2) and so on the set of high charge retention times achieved (\>16000 hours). The device was built via the hybrid integration of natural cellulose fibers, which act simultaneously as substrate and gate dielectric, using amorphous indium zinc and gallium indium zinc oxides respectively for the gate electrode and channel layer. This was complemented by the use of continuous patterned metal layers as source/drain electrodes. {\textcopyright} 2010 Copyright SPIE - The International Society for Optical Engineering.

}, doi = {10.1117/12.841036}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77951757713\&partnerID=40\&md5=5519e40e6d0f6678a5438f39439af305}, author = {Martins, R., Pereira, L., Barquinha, P., Correia, N., Gon{\c c}alves, G., Ferreira, I., Dias, C., Fortunato, E.} } @conference {Fortunato1996269, title = {From intelligent materials to smart sensors}, booktitle = {Proceedings of SPIE - The International Society for Optical Engineering}, volume = {2779}, year = {1996}, note = {

cited By 0

}, pages = {269-274}, abstract = {

A Linear array Thin Film Position Sensitive Detector (LTFPSD) based on hydrogenated amorphous silicon (a-Si:H) is proposed for the first time, taking advantage of the optical properties presented by a-Si:H devices we have developed a LTFPSD with 128 integrated elements able to be used in 3D inspections/measurements. Each element consists on a 1D LTFPSD, based on a p.i.n. diode produced in a conventional PECVD system, where the doped layers are coated with thin resistive layers to establish the required device equipotentials. By proper incorporation of the LTFPSD into an optical inspection camera it will be possible to acquire information about an object/surface, through the optical cross- section method. The main advantages of this system, when compared with the conventional CCDs, are the low complexity of hardware and software used and that the information can be continuously processed (analogue detection).

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029712866\&partnerID=40\&md5=b24d95067875fd9cc1cf671e46c1f853}, author = {Fortunato, Elvira, Lavareda, Guilherme, Martins, Rodrigo, Soares, Fernando, Fernandes, Luis} } @conference {Fortunato1996165, title = {From intelligent materials to smart sensors: a-Si:H position sensitive detectors}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {420}, year = {1996}, note = {

cited By 0

}, pages = {165-170}, abstract = {

This work presents the main static and dynamic performances showed by one dimensional thin film position sensitive detectors (1D TFPSD), based on a-Si:H technology, with a size of 80 mm {\texttimes} 5 mm. The results obtained show that the TFPSD is able to respond to light powers as low as 2μ W/cm2, presenting a detection accuracy, linearity and response frequency better than 10 μm, 2\% and 2 KHz, respectively. These results are quite promising regarding the application of these sensors to a wide variety of optical inspection systems where continuous quality control is required.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030405610\&partnerID=40\&md5=e80b4377078e15bce5c28c2ba026e9f5}, author = {Fortunato, E., Fernandes, M., Soares, F., Lavareda, G., Martins, R.} } @conference {Fortunato2003291, title = {Gallium zinc oxide coated polymeric substrates for optoelectronic applications}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {769}, year = {2003}, note = {

cited By 1

}, pages = {291-296}, abstract = {

Highly transparent and conductive ZnO:Ga thin films were produced by rf magnetron sputtering at room temperature on polyethylene naphthalate substrates. The films present a good electrical and optical stability, surface uniformity and a very good adhesion to the polymeric substrates. The lowest resistivity obtained was 5{\texttimes}10-4 Ωcm with a sheet resistance of 15 Ω/sqr and an average optical transmittance in the visible part of the spectra of 80\%. It was also shown that by passivating the polymeric surface with a thin SiO2 layer, the electrical and structural properties of the films are improved nearly by a factor of 2.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-1542364393\&partnerID=40\&md5=d59e64e9fed43be69af24b45a73b698f}, author = {Fortunato, E., Gon{\c c}alves, A., Marques, A., Assun{\c c}{\~a}o, V., Ferreira, I., {\'A}guas, H., Pereira, L., Martins, R.} } @conference {Fortunato20081199, title = {High mobility indium free amorphous oxide based thin film transistors}, booktitle = {Proceedings of International Meeting on Information Display}, volume = {8}, year = {2008}, note = {

cited By 0

}, pages = {1199-1202}, abstract = {

High mobility bottom gate thin film transistors (TFTs) with an amorphous gallium tin zinc oxide (a-GSZO) channel layer have been produced by rf magnetron cosputtering using a gallium zinc oxide (GZO) and tin (Sn) targets. The effect of the post annealing temperatures (200 {\textdegree}C, 250 {\textdegree}C and 300 {\textdegree}C) was evaluated and compared with two series of TFTs produced at room temperature and 150 {\textdegree}C during the channel deposition. From the results it was observed that the effect ofpos annealing is crucial for both series of TFTs either for stability as well as for improving the electrical characteristics. The a-GSZO TFTs operate in the enhancement mode (n-type), present a high saturation mobility of 24.6 cm2/Vs, a subthreshold gate swing voltage of 0.38 V/decade, a turn-on voltage of -0.5 V, a threshold voltage of 4.6 V and an ION/IOFF ratio of 8x107, satisfying all the requirements to be used in active-matrix backplane.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-65649108570\&partnerID=40\&md5=83f9984d5189b63d64f56f9419613e21}, author = {Fortunato, E.a , Pereira, L.a , Barquinha, P.a , Botelho Do Rego, A.b , Gongalves, G.a , Vil{\`a}, A.c , Morante, J.c , Martins R.a} } @conference {Fortunato2004437, title = {High mobility nanocrystalline indium zinc oxide deposited at room temperature}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {811}, year = {2004}, note = {

cited By 2

}, pages = {437-442}, abstract = {

In this paper we present results of indium doped zinc oxide deposited at room temperature by rf magnetron sputtering, with electron mobility as high as 60 cm2/Vs. The films present a resistivity as low as 5{\texttimes}10 -4 Ωcm with an optical transmittance of 85\%. The structure of these films look-like polymorphous (mixed of different amorphous and nanocrystalline phases from different origins) as detected from XRD patterns (no clear peak exists) with a high smooth surface, as detected from SEM micrographs, highly important to ensure long life time when used in display devices.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-12744259363\&partnerID=40\&md5=3c2364dae2999b48e3f7215954ee0c0c}, author = {Fortunato, E., Pimentel, A., Gon{\c c}alves, A., Marques, A., Martins, R.} } @conference {Fortunato1997949, title = {High sensitivity photochemical sensors based on amorphous silicon}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {467}, year = {1997}, note = {

cited By 4

}, pages = {949-954}, abstract = {

Hydrogenated amorphous silicon photochemical sensors based on Pd-MIS structures were produced by Plasma Enhanced Chemical Vapor Deposition with two different oxidized surfaces (thermal and chemical oxidation). The behaviour of dark and illuminated current-voltage characteristics in air and in the presence of a hydrogen atmosphere is explained by the changes induced by the gases in the work function of the metal, modifying the electrical properties of the interface. The photochemical sensors produced present more than 2 orders of magnitude variation on the reverse dark current when in presence of 400 ppm hydrogen to which it corresponds a decrease of 45\% on the open circuit voltage.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031334288\&partnerID=40\&md5=3a69f00af5db61fb393dbdd1c1afbf3f}, author = {Fortunato, E., Malik, A., Seco, A., Macarico, A., Martins, R.} } @conference {Fortunato1995259, title = {High-detection resolution presented by large-area thin-film position-sensitive detectors}, booktitle = {Proceedings of SPIE - The International Society for Optical Engineering}, volume = {2397}, year = {1995}, note = {

cited By 8

}, pages = {259-270}, abstract = {

The aim of this work is to present the main optoelectronic characteristics of large area 1D position sensitive detectors based on amorphous silicon p-i-n diodes. From that, the device resolution, response time and detectivity are derived and discussed concerning the field of applications of the 1D thin film position sensitive detectors.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029211134\&partnerID=40\&md5=c702589775d230f91db572e164981526}, author = {Fortunato, Elvira, Lavareda, Guilherme, Martins, Rodrigo, Soares, Fernando, Fernandes, Luis} } @conference {Bahubalindruni2013, title = {High-gain amplifier with n-type transistors}, booktitle = {2013 IEEE International Conference of Electron Devices and Solid-State Circuits, EDSSC 2013}, year = {2013}, note = {

cited By 2

}, abstract = {

A high-gain amplifier topology, with all single n-type enhancement transistors, is proposed in this paper. This type of circuits are essential in transparent TFT technologies, such as GIZO and ZnO that lack complementary type transistor. All circuits were simulated using BSIM3V3 model of a 0.35 μm CMOS technology, due to the absence of a complete electrical model for the TFTs. Results reveal that the proposed circuit promise more gain, lower power consumption and higher bandwidth than the existing solutions under identical bias conditions. {\textcopyright} 2013 IEEE.

}, doi = {10.1109/EDSSC.2013.6628203}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84890482228\&partnerID=40\&md5=dd7f4d4986b174667e414613b505ff86}, author = {Bahubalindruni, P.a , Tavares, V.G.a , De Oliveira, P.G.a , Barquinha, P.b , Martins, R.b , Fortunato, E.b} } @conference {Bahubalindruni20132041, title = {High-gain topologies for transparent electronics}, booktitle = {IEEE EuroCon 2013}, year = {2013}, note = {

cited By 2

}, pages = {2041-2046}, abstract = {

Transparent TFT technologies, with amorphous semiconductor oxides are lacking a complementary type transistor. This represents a real challenge, when the design of high-gain amplifiers are considered, without resorting to passive resistive elements. However, some solutions do exist to overcome the lack of a p-type transistor. This paper then presents a comparison analysis of two high-gain single-stage amplifier topologies using only n-type enhancement transistors. In these circuits, high gain is achieved using positive feedback for the load impedance. The comparison is carried out in terms of bandwidth, power consumption and complexity under identical bias conditions. Further, the same load impedance is used to develop a novel high-gain multiplier. All the circuits are simulated using a 0.35 μm CMOS technology, as it is easy to test the reliability of the methods, since CMOS transistors have trustworthy models. {\textcopyright} 2013 IEEE.

}, doi = {10.1109/EUROCON.2013.6625261}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84888605477\&partnerID=40\&md5=2f70987382f501cffe492718698eadf0}, author = {Bahubalindruni, P.a , Tavares, V.G.a , Barquinha, P.b , Martins, R.b , Fortunato, E.b} } @conference {Fortunato2015884, title = {How materials innovations will lead to device revolution?}, booktitle = {2015 Transducers - 2015 18th International Conference on Solid-State Sensors, Actuators and Microsystems, TRANSDUCERS 2015}, year = {2015}, note = {

cited By 0

}, pages = {884-887}, abstract = {

Transparent electronics has gained special attention during the last few years and is today established as one of the most promising technologies for leading the next generation of flat panel display due to its excellent electronic performance. The key components are wide band gap semiconductors, where oxides of different origin play an important role, not only as passive component but also as active component, similar to what we observe in conventional semiconductors like silicon. In this paper we present the recent progress in n- and p-type oxide based thin film transistors (TFT) produced by rf magnetron sputtering and we will summarize the major milestones already achieved with this emerging and very promising technology. {\textcopyright} 2015 IEEE.

}, doi = {10.1109/TRANSDUCERS.2015.7181065}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84955440107\&partnerID=40\&md5=8b23b45e6b345677c660c3039375b32e}, author = {Fortunato, E., Martins, R.} } @conference {{\'A}guas2001, title = {Hydrogenated amorphous silicon / ZnO shottky heterojunction for position sensitive detectors}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {664}, year = {2001}, note = {

cited By 0

}, pages = {A2661-A2666}, abstract = {

In this work a new structure is proposed for position sensitive detectors consisting of glass/Cr/aSi:H(n+)/a-Si:H(i)/ZnO, where the ZnO forms an heterojunction with the a-Si:H(i). The results show that this structure works with success in the fabrication of linear position sensitive detectors. The devices present a good nonlinearity of ≈ 2\% and a good sensitivity to the light intensity. The main advantages of this structure over the classical p-i-n are an easier to built topology and a higher yield due to a better immunity to the a-Si:H pinholes, since the ZnO does not diffuse so easily into a-Si:H as the metal does, which are the cause of frequent failure in the p-i-n devices due to short-circuits caused by the deposition of the metal over the a-Si:H. In this structure the illumination is made directly on the ZnO, so a transparent substrate is not needed and a larger range of substrates can be used.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035559267\&partnerID=40\&md5=8523351b1b64b21a297934d1549d63ca}, author = {{\'A}guas, H., Nunes, P., Fortunato, E., Silva, R., Silva, V., Figueiredo, J., Soares, F., Martins, R.} } @conference {Vieira1995839, title = {Hydrogenated amorphous silicon speed sensor based on the flying spot technique}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {377}, year = {1995}, note = {

cited By 1

}, pages = {839-844}, abstract = {

In the past we have developed a transient technique, called the Flying Spot Technique (FST). FST allows, not only to infer the ambipolar diffusion length but also the effective lifetime of the photogenerated carriers once the light spot velocity and geometry of the structure were known. In this paper, we propose to apply this technique backwards in order to detect the path and velocity of an object that is moving in the direction of a light source. The light reflected back from the object is analyzed through a p.i.n structure being the transient transverse photovoltage dependent on the movement of the object (position and velocity). Assuming that the transport properties of the material and the geometry of the device are known and using a triangulation method we show that it is possible to map the movement of the object. Details concerning material characterization, simulation and device geometry are presented.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029546407\&partnerID=40\&md5=f6678d6b5b5308ddd639338a8c5e179b}, author = {Vieira, M., Fantoni, A., Macarico, A., Soares, F., Evans, G., Martins, R.} } @conference {Vieira1995683, title = {Hydrogenated amorphous silicon speed sensor based on the flying spot technique}, booktitle = {Proceedings of SPIE - The International Society for Optical Engineering}, volume = {2397}, year = {1995}, note = {

cited By 0

}, pages = {683-694}, abstract = {

PIN devices based on hydrogenated amorphous silicon (a-Si:H) became fundamental elements of many different types sensors, based on either the transverse or the lateral photovoltaic effect. In the past we have developed a transient technique, called the Flying Spot Technique (FST), based on the lateral photoeffect. FST allows, not only to infer the ambipolar diffusion length but also the effective lifetime of the photogenerated carriers once the light spot velocity and geometry of the structure were known. In this paper we propose to apply this technique backwards in order to detect the path and velocity of an object that is moving in a light source direction. The light reflected back from the object is analyzed through p.i.n. structure being the transient transverse photovoltage dependent on the object movement (position and velocity). Assuming known the transport properties of the material and the geometry of the device and using a triangulation method we show that it is possible to map the object movement. Details concerning material characterization, simulation and device geometry are presented.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029231646\&partnerID=40\&md5=81d5405585a5deaddce24d22f219ca0f}, author = {Vieira, Manuela, Fantoni, Alessandro, Macarico, A.Felipe, Soares, Fernando, Martins, Rodrigo} } @conference {Lavareda199659, title = {Improved a-Si:H TFT performance using a-Six-Ni1-x/a-SixC1-x stack dielectrics}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {424}, year = {1996}, note = {

cited By 1

}, pages = {59-64}, abstract = {

In this paper we present a study on the electrical characteristics (conductivity, σ and relative dielectric constant, εr) of amorphous silicon nitride (a-SixN1-x) and carbide (a-SixC1-x) films deposited by PECVD, used as dielectric materials in TFT devices, aiming to select the most adequate alloy that lead to improve device performances. Besides that, double stack a-SixN1-x/a-SixC1-x structures were developed and applied as dielectric layers on TFTs, whose performances show to be superior to those ones using single silicon nitride or silicon carbide as dielectric.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030399823\&partnerID=40\&md5=4e4eecf30f5c81dd94a29596a1017d06}, author = {Lavareda, G., Fortunato, E., Carvalho, C.Nunes, Martins, R.} } @conference {NunesdeCarvalho1996861, title = {Improvement of the ITO-p interface in a-Si:H solar cells using a thin SiO intermediate layer}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {420}, year = {1996}, note = {

cited By 1

}, pages = {861-865}, abstract = {

The use of ITO thin films on glass/ITO/p-i-n/metal amorphous silicon solar cells is reviewed. It is suggested a new application for silicon monoxide thin films on the ITO-p interface, as an intermediate layer, to minimize the ITO thin film deterioration process, during the early stage of exposure to a silane plasma rich in hydrogen. The thickness of the silicon monoxide thin films is chosen not to worsen the optical and electrical properties of the ITO thin films. The ITO-p interface is optimized (due to impurities diffusion decrease), leading to an overall improvement of the device performance.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030407693\&partnerID=40\&md5=36f09248d418819f380bd5c995d8d881}, author = {Nunes de Carvalho, C., de Nijs, J.M.M., Ferreira, I., Fortunato, E., Martins, R.} } @conference {deCarvalho199625, title = {Improvement of the ITO-P interface in a-Si:H solar cells using a thin SiO intermediate layer}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {426}, year = {1996}, note = {

cited By 0

}, pages = {25-29}, abstract = {

The use of ITO films on glass/ITO/p-i-n/metal amorphous silicon solar cells is reviewed. It is suggested a new application for silicon monoxide thin films on the ITO-p interface, as an intermediate layer, to minimize the ITO thin film deterioration process, during the early stage of exposure to a silane plasma rich in hydrogen. The thickness of the silicon monoxide thin films is chosen not to worsen the optical and electrical properties of the ITO thin films. The ITO-p interface is optimized (due to impurities diffusion decrease), leading to an overall improvement of the device performance.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030380927\&partnerID=40\&md5=e78c732740cf51a4a3acd6773ef1ac4d}, author = {de Carvalho, C.Nunes, de Nijs, J.M.M., Ferreira, I., Fortunato, E., Martins, R.} } @conference {Raniero2005543, title = {Influence of hydrogen plasma on electrical and optical properties of transparent conductive oxides}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {862}, year = {2005}, note = {

cited By 0

}, pages = {543-548}, abstract = {

In this work we study the optical and electrical behavior of ZnO:Ga, ITO and IZO films deposited on glass after sustaining different hydrogen plasma conditions and exposure times. This work was complemented by analyzing the surface morphology of the set of films, which allow us to determine the role of hydrogen plasma on the film{\textquoteright}s properties such as Hall mobility, free carrier concentration, sheet resistance, optical transmittance, figure of merit and state of the surface. Apart from that, the performances of solar cells using an intrinsic layer constituted by nanocrystalline silicon will be also presented. The data show that the electrical properties of solar cells were improved by using ZnO:Ga as front contact, allowing a high current density collection and single pin solar cells with efficiencies exceeding 11\%. {\textcopyright} 2005 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-30644469792\&partnerID=40\&md5=73948bf7714962bb18ad8ee8f1271ec1}, author = {Raniero, L., Gon{\c c}alves, A., Pimentel, A., Ferreira, I., Zhang, S., Pereira, L., {\'A}guas, H., Fortunato, E., Martins, R.} } @conference {Kondaiah2012, title = {Influence of substrate bias voltage on the physical, electrical and dielectric properties of RF magnetron sputtered TiO 2 films}, booktitle = {IOP Conference Series: Materials Science and Engineering}, volume = {30}, number = {1}, year = {2012}, note = {

cited By 1

}, abstract = {

Titanium oxide (TiO 2) finds potential applications in various fields such as solar cells, optical coatings due to its high refractive index and it also has been widely used in memory devices owing to its high dielectric constant. TiO 2 films have been deposited on p-type silicon (100) substrates by RF magnetron sputtering technique. Thickness, structure and surface morphology of the films were analyzed by using α-step profilometer, Raman spectroscopy and atomic force microscope respectively. Thin film capacitors of the type Al/TiO 2/Si were fabricated by evaporation of Aluminium on to the TiO 2 films. The current - voltage and capacitance - voltage characteristics were carried out to understand the electrical conduction and dielectric properties of the deposited films with a stack of Al/TiO 2/Si. The leakage current density was decreased and capacitance was increased with increase of substrate bias voltage.

}, doi = {10.1088/1757-899X/30/1/012005}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84858213569\&partnerID=40\&md5=1b5b835ce4fd25ade17f0c92018b5bd6}, author = {Kondaiah, P.a , Sekhar, M.C.a , Chandra, S.V.J.b , Martins, R.b , Uthanna, S.a , Elangovan, E.b} } @conference {Wang20061010, title = {Influence of the ex-situ and in-situ annealed self-buffer layer on ZnO film}, booktitle = {Physica Status Solidi C: Conferences}, volume = {3}, number = {4}, year = {2006}, note = {

cited By 1

}, pages = {1010-1013}, abstract = {

Two self-buffer layers were grown on c-plane sapphire substrates by atmospheric MOCVD method using DEZn, tert-butanol as precursors and H 2 as carrier gas. Then, they were respectively annealed in growth process and oxygen environment. After that, ZnO films were respectively grown on them. XRD spectra show that all the films were grown in [002] orientation. Furthermore, the film with a buffer layer annealed in oxygen exhibits much higher crystal quality. Its FWHM of the rocking curve is only 567arcsec. Furthermore, its Raman scattering spectrum appears a much stronger E2 mode peak at 436cm-1 and its PL spectrum appears a shoulder at 3.367eV on the higher energy side. {\textcopyright} 2006 WILEY-VCH Verlag GmbH \& Co. KGaA,.

}, doi = {10.1002/pssc.200564704}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33646242258\&partnerID=40\&md5=b1d58b240fe670937288805b904e49c3}, author = {Wang, J.c , Sallet, V.a , Amiri, G.a , Rommelluere, J.-F.a , Lusson, A.a , Rzepka, E.a , Lewis, J.E.b , Galtier, P.a , Fortunato} } @conference {Ferreira1999831, title = {Influence of the H2 dilution and filament temperature on the properties of P doped silicon carbide thin films produced by hot-wire technique}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {507}, year = {1999}, note = {

cited By 1

}, pages = {831-836}, abstract = {

This work deals with the role of hydrogen dilution and filament temperature on the morphology, structure and electrical properties of nanocrystalline boron doped silicon carbide thin films produced by hot-wire technique. The structural and morphological data obtained by XRD, SEM and micro-Raman show that for filament temperatures and hydrogen dilutions above 2100 {\textdegree}C and 90\%, respectively, the surface morphology of the films is granular with a needle shape, while for lower filament temperatures and hydrogen dilutions the surface morphology gets honeycomb like. The SIMS analysis reveals that films produced with filament temperatures of about 2200 {\textdegree}C and hydrogen dilution of 99\% present a higher hydrogen and carbon incorporation than the films produced at lower temperatures and hydrogen dilutions. These results agree with the electrical and optical characteristics recorded that show that the films produced exhibit optical gaps in the range from 1.8 to 2 eV and transverse conductivities ranging from 10-1 S/cm to 10-3 S/cm, consistent with the degree of films crystallinity and carbon incorporation recorded.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032678424\&partnerID=40\&md5=81996dc8d0f5fec657735b6a59067cc5}, author = {Ferreira, I., Aguas, H., Mendes, L., Fernandes, F., Fortunato, E., Martins, R.} } @conference {Fortunato2000, title = {Large area flexible amorphous silicon position sensitive detectors}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {609}, year = {2000}, note = {

cited By 0

}, pages = {A1271-A1276}, abstract = {

Large area thin film position sensitive detectors based on amorphous silicon technology have been prepared on polyimide substrates using the conventional plasma enhanced chemical vapour deposition technique. The sensors have been characterised by spectral response, illuminated I-V characteristics and position detectability measurements. The obtained one dimensional position sensors with 5 mm wide and 60 mm long present a maximum spectral response at 600 nm, an open circuit voltage of 0.6 V{\textdegree} and a position detectability with a correlation of 0.9989 associated to a standard deviation of 1 {\texttimes} 10-2, comparable to those ones produced on glass substrates. The surface of the sensors at each stage of fabrication was investigated by Atomic Force Microscopy.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034429062\&partnerID=40\&md5=98b4472d657947205bf363a32aacc2ae}, author = {Fortunato, E.M.C., Brida, D., Ferreira, I.M.M., {\'A}guas, H.M.B., Nunes, P., Cabrita, A., Giuliani, F., Nunes, Y., Maneira, M.J.P.,} } @conference {Fortunato1993981, title = {Large area position sensitive detector based on amorphous silicon technology}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {297}, year = {1993}, note = {

cited By 16

}, pages = {981-986}, abstract = {

We have developed a rectangular dual-axis large area Position Sensitive Detector (PSD), with 5 cm{\texttimes}5 cm detection area, based on PIN hydrogenated amorphous silicon (a-Si:H) technology, produced by Plasma Enhanced Chemical Vapor Deposition (PECVD). The metal contacts are located in the four edges of the detected area, two of them located on the back side of the ITO/PIN/Al structure and the others two located in the front side. The key factors of the detectors resolution and linearity are the thickness uniformity of the different layers, the geometry and the contacts location. Besides that, edge effects on the sensor{\textquoteright}s corner disturb the linearity of the detector. In this paper we present results concerning the linearity of the detector as well as its optoelectronic characteristics and the role of the i-layer thickness on the final sensor performances.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027805697\&partnerID=40\&md5=8bf371378f5c2a4564c2bd7c9f54b9b5}, author = {Fortunato, E., Vieira, M., Ferreira, L., Carvalho, C.N., Lavareda, G., Martins, R.} } @conference {Malik1998257, title = {Light-controlled switching transients in MIS silicon structures with multichannel insulator: physical processes and new device modelling}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {490}, year = {1998}, note = {

cited By 0

}, pages = {257-262}, abstract = {

We present the modelling of a new two-terminal and low-voltage operating optoelectronic device based on MIS silicon structure with multichannel insulator and having as gate a transparent metallic tin-doped indium oxide (ITO) layer deposited by spray pyrolysis technique over the insulator layer. ITO layer has a multiple non-rectifier electrical contact with silicon substrate, in the SiO2 channel{\textquoteright}s region. Construction details of the process, together with its operating characteristics are given. The devices developed do not require external active electronic components (transistors, microschemes) to execute their functions and to transform analogue input optical signals to digital output form, highly important for a wide range of optoelectronic applications.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032299021\&partnerID=40\&md5=325a21de748c0b7e3b75849cb1b0bf79}, author = {Malik, A., Martins, R.} } @conference {Martins1995148, title = {Linear thin-film position-sensitive detector (LTFPSD) for 3D measurements}, booktitle = {Proceedings of SPIE - The International Society for Optical Engineering}, volume = {2415}, year = {1995}, note = {

cited By 3

}, pages = {148-158}, abstract = {

A linear array thin film position sensitive detector (LTFPSD) based on hydrogenated amorphous silicon (a-Si:H) is proposed for the first time, taking advantage of the optical properties presented by a-Si:H devices we have developed a LTFPSD with 128 integrated elements able to be used in 3-D inspections/measurements. Each element consists on a one-dimensional LTFPSD, based on a p.i.n. diode produced in a conventional PECVD system, where the doped layers are coated with thin resistive layers to establish the required device equipotentials. By proper incorporation of the LTFPSD into an optical inspection camera it is possible to acquire information about an object/surface, through the optical cross-section method. The main advantages of this system, when compared with the conventional CCDs, are the low complexity of hardware and software used and that the information can be continuously processed (analogue detection).

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029194415\&partnerID=40\&md5=a52b8eb591e5d899f07da5225e4d7bc3}, author = {Martins, Rodrigo, Lavareda, Guilherme, Fortunato, Elvira, Soares, Fernando, Fernandes, Luis, Ferreira, Luis} } @conference {Malik1998375, title = {Metal oxide/silicon heterostructures: New solutions for different optoelectronic applications}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {487}, year = {1998}, note = {

cited By 1

}, pages = {375-380}, abstract = {

In this paper we report the success in fabricating FTO/Si surface-barrier photodiodes produced by spray pyrolysis deposition technique, under ambient conditions. Three types of photodetectors for low-voltage-bias operation were developed based on high-resistivity silicon: 1. X-Ray detectors with energy resolution of 16.5\% at 661.5 keV (137Cs source), consisting of surface-barrier PIN photodiode with an active area of 50 mm2 operating at 5 V reverse bias, scintillator based on monocrystalline Bi4Ge3O12 and preamplifier (noise of 250 e- RMS.); 2. Fast-response surface-barrier FTO/n{\textendash}n+ silicon epitaxial photodiodes, operating at 10 V bias with rise times of 2 ns at λ = 0.85 μm; 3. Radiation-resistant drift epitaxial surface-barrier PIN photodiodes for unbiased operating conditions, with an exponential impurity distribution in a 8 μm thick epitaxial layer. A built-in electrical field due to the carrier concentration distribution in the epitaxial layer provides a considerable improvement in the {\textquoteleft}critical fluence{\textquoteright} value (3{\texttimes}1014 cm-2) for neutron irradiation.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031623393\&partnerID=40\&md5=0b90bc88b36c8285a3de0699c59c486e}, author = {Malik, A., Martins, R.} } @conference {Guimaraes1982546, title = {MODEL FOR ANALYSIS OF OPTICAL MEASUREMENTS CARRIED ON a-Si:H FILMS FOR PHOTOVOLTAIC APPLICATIONS.}, booktitle = {Commission of the European Communities, (Report) EUR}, year = {1982}, note = {

cited By 0

}, pages = {546-555}, abstract = {n/a}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020258677\&partnerID=40\&md5=5cdebd1a8b9be99db6081a0cfce7f14e}, author = {Guimaraes, L., Martins, R., Dias, A.G., Barradas, F.} } @conference {Fernandes2007469, title = {Modeling the laser scanned photodiode S-shaped J-V characteristic}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {989}, year = {2007}, note = {

cited By 0

}, pages = {469-474}, abstract = {

The devices analyzed in this work present an S-shape J-V characteristic when illuminated. By changing the light flux a non linear dependence of the photocurrent with illumination is observed. Thus a low intensity light beam can be used to probe the local illumination conditions, since a relationship exists between the probe beam photocurrent and the steady state illumination. Numerical simulation studies showed that the origin of this S-shape lies in a reduced electric field across the intrinsic region, which causes an increase in the recombination losses. Based on this, we present a model for the device consisting of a modulated barrier recombination junction in addition to the p-i-n junction. The simulated results are in good agreement with the experimental data. Using the presented model a good estimative of the LSP signal under different illumination conditions can be obtained, thus simplifying the development of applications using the LSP as an image sensor, with advantages over the existing imaging systems in the large area sensor fields with the low cost associated to the amorphous silicon technology. {\textcopyright} 2007 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-41549088900\&partnerID=40\&md5=08223d7e0708b6956f2f52b4029163f2}, author = {Fernandes, M.a , Vieira, M.a , Martins, R.b} } @conference {Fantoni1994711, title = {Modelling heteroface of P.I.N solar cells for improving stability}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {336}, year = {1994}, note = {

cited By 13

}, pages = {711-716}, abstract = {

The introduction into a traditional p.i.n structure of two defective buffer layers near the p/i and i/n interfaces can improve the device stability and efficiency through an enhancement of the electric field profile at the interfaces and a reduction of the available recombination bulk centers. The defectous layer ("i'-layer"), grown at a higher power density, present a high density of defects and acts as "gettering centers" able to tailor light induced defects under degradation conditions. If the i-layer density of states remains below 1016 eV-1 cm-3 and assuming a Gaussian distribution of defect states, the gettering center distribution will not affect significantly the carrier population but only its spatial distribution. We report here about a device numerical simulation that allows us to analyse the influence of the "i'-layer" position, thickness and density of states on the a-Si: H solar cells performances. Results of some systematic simulation from the ASCA program (Amorphous Solar Cell Analysis), and for different configurations will be presented. {\textcopyright} 1994 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897584858\&partnerID=40\&md5=2a28d4345b354bb4e8ebae7a8195059d}, author = {Fantoni, A., Vieira, M., Martins, R.} } @conference {Elangovan200535, title = {Molybdenum doped indium oxide thin films prepared by rf sputtering}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {905}, year = {2005}, note = {

cited By 1

}, pages = {35-40}, abstract = {

Molybdenum doped indium oxide (IMO) thin films rf sputtered at room temperature were studied as a function of oxygen volume percentage (O 2 vol. \%) varied between 0 and 17.5. The as-deposited films were amorphous irrespective of O2 vol. \%. The minimum transmittance (\<10 \%) of the films deposited without oxygen has been increased on introducing oxygen (3.5 O2 vol. \%) to a maximum of 90 \%. The optical band gap has been increased from 3.80 eV (without oxygen) to 3.92 eV (3.5 O 2 vol. \%). The films were highly resistive and the hall coefficients were detectable only for the films deposited without oxygen. In order to increase the electrical conductivity, the films were annealed in the range 100-500{\textdegree} C in open-air and N2/H: gas for 1 hour. The annealed films become polycrystalline with enhanced electrical and optical properties. The effect of annealing conditions on these films will be presented and discussed in detail. {\textcopyright} 2006 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34249935187\&partnerID=40\&md5=940670d87a3300677ecd39e17e874e42}, author = {Elangovan, E., Marques, A., Pimentel, A., Martins, R., Fortunato, E.} } @conference {Pereira2012, title = {Multicomponent dielectrics for oxide TFT}, booktitle = {Proceedings of SPIE - The International Society for Optical Engineering}, volume = {8263}, year = {2012}, note = {

cited By 0

}, abstract = {

In this work we present sputtered multicomponent dielectrics based on mixtures of HfO 2 and SiO 2. This way it is possible to get stable amorphous structure up to 800{\textdegree}C, that does not happen for pure HfO 2, for instance, that present a polycrystalline structure when deposited without any intentional substrate heating. Besides, also the band gap of the resulting films is increased when compared with pure HfO2 that theoretically is an advantage in getting a suitable band offset with the semiconductor layer on oxide TFTs. Concerning the electrical characterization, the leakage current on c-Si MIS structures is low as 10 -9 Acm -2 at 10 V. The amorphous structure of the films also lead to better dielectric/semiconductor interfaces, as suggested by C-V characteristics on GIZO MIS structures, which do not present strong variation with frequency. On other hand, the dielectric constant decreases due to the incorporation of SiO 2 and Al 2O 3. Further improvement on insulating and interface characteristics is achieved using multilayer stacks and substrate bias during deposition. {\textcopyright} 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

}, doi = {10.1117/12.909454}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84858605335\&partnerID=40\&md5=6f1c4120d62c59d1922884bbe4f9c97b}, author = {Pereira, L., Barquinha, P., Gon{\c c}alves, G., Fortunato, E., Martins, R.} } @conference {Fortunato2006605, title = {Multicomponent wide band gap oxide semiconductors for thin film transistors}, booktitle = {Proceedings of International Meeting on Information Display}, volume = {2006}, year = {2006}, note = {

cited By 0

}, pages = {605-608}, abstract = {

The recent application of wide band gap oxide semiconductors to transparent thin film transistors (TTFTs) is making a fast and growing (r)evolution on the contemporary solid-state electronics. In this paper we present some of the recent results we have obtained using wide band gap oxide semiconductors, like indium zinc oxide, produced by rf sputtering at room temperature. The devices work in the enhancement mode and exhibit excellent saturation drain currents. On-off ratios above 106 are achieved. The optical transmittance data in the visible range reveals average transmittance higher than 80\%, including the glass substrate. Channel mobilities are also quite respectable, with some devices presenting values around 25 cm2/Vs, even without any annealing or other post deposition improvement processes. The high performances presented by these TTFTs associated to a high electron mobility, at least two orders of magnitude higher than that of conventional amorphous silicon TFTs and a low threshold voltage, opens new doors for applications in flexible, wearable, disposable portable electronics as well as battery-powered applications.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33846152612\&partnerID=40\&md5=a35c43a92aac3cda4607e94a5cd67008}, author = {Fortunato, E., Barquinha, P., Pereira, L., Gon{\c c}alves, G., Martins, R.} } @conference {Bahubalindruni2012955, title = {Multipliers with transparent a-GIZO TFTs using a neural model}, booktitle = {2012 20th Telecommunications Forum, TELFOR 2012 - Proceedings}, year = {2012}, note = {

cited By 3

}, pages = {955-958}, abstract = {

This paper presents the results of a preliminary study to examine the ability of post-silicon devices for analog processing. It is focused on the latest thin-film transistors (TFTs) with amorphous gallium-indium-zinc oxide (a-GIZO) as active layer. Three circuit configurations are presented: a differential pair and two multiplier topologies. Both triode and saturation regions of operation are included in the analysis, with the devices set to remain in strong accumulation. A neural model, which is developed based on the measured data of the TFTs, is used for the circuit simulations in the Cadence Virtuoso environment. The analog multipliers simulation results are compared against the expected functional results. {\textcopyright} 2012 IEEE.

}, doi = {10.1109/TELFOR.2012.6419367}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84874151743\&partnerID=40\&md5=ed6bf96fb2d089615cd34c90686bd1d9}, author = {Bahubalindruni, G.a , Duarte, C.a , Tavares, V.G.a , Barquinha, P.b , Martins, R.b , Fortunato, E.b , De Oliveira, P.G.a} } @conference {Ferreira2000, title = {N-type silicon films produced by hot wire technique}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {609}, year = {2000}, note = {

cited By 0

}, pages = {A651-A656}, abstract = {

The role of the deposition pressure (p) and the type of filaments (tungsten, W or tantalum, Ta) used to produce large area (10cm{\texttimes}10cm) n-type Si:H films by hot wire chemical vapour (HW-CVD) deposition technique was investigated. The data show that the electro-optical properties of the films produced are dependent on the gas pressure used. In the pressure range of 1{\texttimes}10-3 Torr to 1.0 Torr, the room dark conductivity (σd) varies from 1{\texttimes}10-8 to 2 S/cm for films produced at the same hydrogen dilution and filament temperature (Tfil). On the other hand, the hydrogen concentration (CH) decreases from 10\% to 2\%, while the growth rate (R) shows an exponential increase, from 1 to 9 {\r A}/s. The SIMS analysis, within the detection limits, does not reveal the existence of any significant W or Ta contamination in the films produced.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034429670\&partnerID=40\&md5=91ced8d08893bd26cc0f7f1458ce1bc5}, author = {Ferreira, I.M.M., Cabrita, A.M.F., Fortunato, E.M.C., Martins, R.F.P.} } @conference {Ferreira2000, title = {Nanocrystalline undoped silicon films produce by hot wire plasma assisted technique}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {609}, year = {2000}, note = {

cited By 1

}, pages = {A2241-A2246}, abstract = {

In this work, we show results concerning electro-optical properties, composition and morphology of nanocrystalline hydrogenated undoped silicon (nc-Si:H) films produced by hot wire plasma assisted chemical vapour deposition process (HWPA-CVD) and exhibiting a compact granular structure, as revealed by SEM micrographs. This was also inferred by infrared spectra, which does not present the SiO vibration band located at 1050-1200 cm-1, even when samples have long atmospheric exposition. The photoconductivity measured at room temperature also does not change when samples have a long time exposition to the air or to the light irradiation. The influence of hydrogen dilution on the properties of the films was also investigated.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034429772\&partnerID=40\&md5=96c416c9ec3bc598b9f0c7c09573e221}, author = {Ferreira, I.M.M., Martins, R.F.P., Cabrita, A.M.F., Fortunato, E.M.C., Vilarinho, P.} } @conference {Martins2001, title = {Nanostructured silicon films produced by PECVD}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {664}, year = {2001}, note = {

cited By 3

}, pages = {A961-A966}, abstract = {

This paper presents the process conditions that lead to the production of nanostructured silicon films grown by plasma enhanced chemical vapour deposition close to the so-called gamma regime (powder formation), highly dense and with low density of bulk states. Thus, the powder management is one important issue to be addressed in this paper. As a general rule we observed that high quality films (low density of states and high μτ products) are obtained when films are grown under low ion bombardment at high hydrogen dilution and deposition pressure conditions, to allow the proper surface passivation and surface activation.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035558270\&partnerID=40\&md5=c1c2c5baefbff333211620a69b9f1118}, author = {Martins, R., {\'A}guas, H., Silva, V., Ferreira, I., Cabrita, A., Fortunato, E.} } @conference {Carvalho1995915, title = {Nd-YAG laser induced crystallization on a-Si:H thin films}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {358}, year = {1995}, note = {

cited By 1

}, pages = {915-920}, abstract = {

In this paper we present results concerning the influence of laser energy and shot density on the electrical resistance, X-ray diffraction pattern, and structure obtained by SEM, on recrystallized a-Si:H thin films produced by using a Nd-YAG laser, working in a wavelength of 532 nm. The base material (undoped and doped a-Si:H) was obtained by Plasma Enhanced Chemical Vapour Deposition (PECVD). The structure and electrical characteristics of the recrystallized thin films are dependent on the laser beam energy density, beam spot size and the number of shots applied to the base a-Si:H thin film used. Overall, the data show recrystallized material with grain sizes larger than 1μm, where the electrical resistance of both, undoped and doped materials, can be varied up to 5 orders of magnitude, by the proper choice of the recrystallization conditions.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029222782\&partnerID=40\&md5=7d2af491f7ccd177d7a96528b5e09a92}, author = {Carvalho, J., Ferreira, I., Fernandes, B., Fidalgo, J., Martins, R.} } @conference {Fortunato20111681, title = {New developments on oxide electronics}, booktitle = {Proceedings of the International Display Workshops}, volume = {3}, year = {2011}, note = {

cited By 1

}, pages = {1681-1684}, abstract = {

In this article we review the recent progress in n- and p-type oxide based thin film transistors (TFT), with special emphasis to solution-processed and p-type, and we will summarize the major milestones already achieved with this emerging and very promising technology.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84870703219\&partnerID=40\&md5=5754a749725171288fbd20b397b544d1}, author = {Fortunato, E., Barquinha, P., Martins, R.} } @conference {Fortunato1995797, title = {New linear array thin film position sensitive detector (LTFPSD) for 3D measurements}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {377}, year = {1995}, note = {

cited By 8

}, pages = {797-802}, abstract = {

A Linear array Thin Film Position Sensitive Detector (LTFPSD) based on hydrogenated amorphous silicon (a-Si:H) is proposed for the first time, taking advantage of the optical properties presented by a-Si:H devices we have developed a LTFPSD with 128 integrated elements able to be used in 3D inspections/measurements. Each element consists on an one-dimensional TFPSD, based on a p.i.n. diode produced in a conventional PECVD system, where the doped layers are coated with thin resistive layers to establish the required device equipotentials. By proper incorporation of the LTFPSD into an optical inspection camera it will be possible to acquire information about an object/surface, through the optical cross-section method. The main advantages of this system, when compared with the conventional CCDs, are the low complexity of hardware and software used and that the information can be continuously processed (analogue detection).

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029538071\&partnerID=40\&md5=d24067db181af4c0473521a08740aba7}, author = {Fortunato, E., Soares, F., Lavareda, G., Martins, R.} } @conference {Fortunato2004347, title = {Next generation of thin film transistors based on zinc oxide}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {811}, year = {2004}, note = {

cited By 0

}, pages = {347-352}, abstract = {

We report high performance ZnO thin film transistor (ZnO-TFT) fabricated by rf magnetron sputtering at room temperature with a bottom gate configuration. The ZnO-TFT operates in the enhancement mode with a threshold voltage of 19 V, a field effect mobility of 28 cm2/Vs, a gate voltage swing of 1.39 V/decade and an on/off ratio of 3{\texttimes}105. The ZnO-TFT present an average optical transmission (including the glass substrate) of 80\% in the visible part of the spectrum. The combination of transparency, high field-effect mobility and room temperature processing makes the ZnO-TFT a very promising low cost optoelectronic device for the next generation of invisible and flexible electronics.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-12744271549\&partnerID=40\&md5=00afac3b696404f2cf56fb72aeb02b69}, author = {Fortunato, E., Barquinha, P., Pimentel, A., Gon{\c c}alves, A., Pereira, L., Marques, A., Martins, R.} } @conference {Elangovan20061, title = {A next generation TCO material for display systems: Molybdenum doped indium oxide thin films}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {936}, year = {2006}, note = {

cited By 0

}, pages = {1-6}, abstract = {

Thin films of indium molybdenum oxide (IMO) were rf sputtered onto glass substrates at room temperature. The films were studied as a function of sputtering power (ranging 40-180 W) and sputtering time (ranging 2.5-20 min). Thickness of the films found varied between 50-400 nm. The films were characterized for their structural (XRD), electrical (Hall measurements) and optical (Transmittance spectra) properties. XRD studies revealed that the films are amorphous for the sputtering power <= 100 W and deposition time <= 5 min. All the other films are polycrystalline and the strongest refection along (222) plane showing a preferential orientation. A minimum bulk resistivity of 2.65 {\texttimes} 10-3 Ω-cm and a maximum carrier concentration of 4.16 {\texttimes} 1020 cm-3 have been obtained for the films sputtered at 180 W (10 min). Whereas maximum mobility (19.5 cm2 V-1 s-1) has been obtained for the films sputtered at 80 W (10 min). A maximum visible transmittance of 90\% (500 nm) has been obtained for the films sputtered at 80 W (10 min) with a minimum of 27\% for those sputtered at 180 W. The optical band gap of the films found varying between 3.75 and 3.90 eV for various sputtering parameters. {\textcopyright} 2006 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33947643780\&partnerID=40\&md5=830becec51dfad38c219a4164fb7b1b6}, author = {Elangovan, E., Marques, A., Martins, R., Fortunato, E.} } @conference {Bahubalindruni20162098, title = {Novel linear analog-adder using a-IGZO TFTs}, booktitle = {Proceedings - IEEE International Symposium on Circuits and Systems}, volume = {2016-July}, year = {2016}, note = {

cited By 0

}, pages = {2098-2101}, abstract = {

A novel linear analog adder is proposed only with n-type enhancement IGZO TFTs that computes summation of four voltage signals. However, this design can be easily extended to perform summation of higher number of signals, just by adding a single TFT for each additional signal in the input block. The circuit needs few number of transistors, only a single power supply irrespective of the number of voltage signals to be added, and offers good accuracy over a reasonable range of input values. The circuit was fabricated on glass substrate with the annealing temperature not exceeding 200{\textdegree} C. The circuit performance is characterized from measurements under normal ambient at room temperature, with a power supply voltage of 12 V and a load of ≈ 4 pF. The designed circuit has shown a linearity error of 2.3\% (until input signal peak to peak value is 2 V), a power consumption of 78 μW and a bandwidth of ≈ 115 kHz, under the worst case condition (when it is adding four signals with the same frequency). In this test setup, it has been noticed that the second harmonic is 32 dB below the fundamental frequency component. This circuit could offer an economic alternative to the conventional approaches, being an important contribution to increase the functionality of large area flexible electronics. {\textcopyright} 2016 IEEE.

}, doi = {10.1109/ISCAS.2016.7538993}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983450915\&partnerID=40\&md5=df71a54191ab55599eac0c4989cdae6b}, author = {Bahubalindruni, P.G.a c , Tavares, V.G.b , Fortunato, E.a , Martins, R.a , Barquinha, P.a} } @conference {Silva2007935, title = {Novel Optoelectronic platform using an amorphous/nanocrystalline Silicon biosensor for the specific identification of unamplified nucleic Acid sequences based on gold nanoparticle probes}, booktitle = {TRANSDUCERS and EUROSENSORS {\textquoteright}07 - 4th International Conference on Solid-State Sensors, Actuators and Microsystems}, year = {2007}, note = {

cited By 1

}, pages = {935-938}, abstract = {

Here we describe an innovative optoelectronic platform which enables the specific detection of unamplified nucleic acid sequences with the integration of oligonucleotide-derivatized gold nanoparticles, a colour sensor and a light emission source for a colorimetric detection method. This new low cost, fast and simple optoelectronic platform permits detection of less than 1 picomole quantities of nucleic acid without target or signal amplification. {\textcopyright}2007 IEEE.

}, doi = {10.1109/SENSOR.2007.4300285}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-50049088123\&partnerID=40\&md5=9d5346b813092a8cb218d435854d29c7}, author = {Silva, L.B.a , Baptista, P.b , Raniero, L.c , Doria, G.b , Franco, R.d , Martins, R.a , Fortunato, E.a} } @conference {Fantoni1997234, title = {Numerical simulation of a/μc-Si:H p-i-n photo-diode under non-uniform illumination: A 2D transport problem}, booktitle = {Proceedings of SPIE - The International Society for Optical Engineering}, volume = {2997}, year = {1997}, note = {

cited By 0

}, pages = {234-243}, abstract = {

We report here about a computer simulation program, based on a comprehensive physical and numerical model of an a/μc-Si:H p-i-n device, applied to the 2D problem of describing the transport properties within the structure under non- uniform illumination. The continuity equations for holes and electrons together with Poisson{\textquoteright}s equation are solved simultaneously along the two directions parallel and perpendicular to the junction. The basic semiconductor equations are implemented with a recombination mechanism reflecting the microcrystalline structure of the different layers. The lateral effects occurring within the structure, due to the non-uniformity of the radiation are outlined. The simulation results obtained for different wavelengths of the incident light are compared and shown their dependence on the energy of the radiation. The results of simulating a p-i-n μc-Si:H junctions under non-uniform illumination is that the generated lateral effects depend not only in intensity but also in direction on the wavelength of the incident radiation. {\textcopyright}2004 Copyright SPIE - The International Society for Optical Engineering.

}, doi = {10.1117/12.264153}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-58649092192\&partnerID=40\&md5=625cdf5d48d4b6f6bb05e3c544826383}, author = {Fantoni, A., Vieira, M., Cruz, J., Martins, R.} } @conference {Pereira200545, title = {Optimization of the metal/silicon ratio on nickel assisted crystallization of amorphous silicon}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {869}, year = {2005}, note = {

cited By 0

}, pages = {45-50}, abstract = {

The aim of this work is to optimize the metal/silicon ratio on nickel metal induced crystallization of silicon. For this purpose amorphous silicon layers with 80, 125 and 220 nm thick were used on the top of which 0.5 nm of Ni was deposited and annealed during the required time to full crystallize the a-Si. The data show that the 80 nm a-Si layer reaches a crystalline fraction of 95.7\% (as detected by spectroscopic ellipsometry) after annealed for only 2 hours. No significant structural improvement is detected by ellipsometry neither by XRD when annealing the films for longer times. However, on 125 nm thick samples, after annealing for 2 hours the crystalline fraction is only 59.7\%, reaching a similar value to the one with 80 nm only after 5 hours, with a crystalline fraction of 92.2\%. Here again no significant improvements were achieved by using longer annealing times. Finally, the 220 nm thick a-Si sample is completely crystallized only after 10 hours annealing. These data clear suggest that the crystallization of thicker a-Si layers requires thicker Ni films to be effective for short annealing times. A direct dependence of the crystallization time on the metal/silicon ratio was observed and estimated. {\textcopyright} 2005 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-30644466025\&partnerID=40\&md5=54a4719f28b21d14706c9ee4e0fd461c}, author = {Pereira, L.a , Beckers, M.b , Martins, R.M.S.b , Fortunato, E.a , Martins, R.a} } @conference {Barquinha20101376, title = {P-202L: Late-news poster: Long-term stability of oxide semiconductor-based TFTs}, booktitle = {48th Annual SID Symposium, Seminar, and Exhibition 2010, Display Week 2010}, volume = {3}, year = {2010}, note = {

cited By 1

}, pages = {1376-1379}, abstract = {

Long-term electrical stability measurements, including current/bias stress and aging over 18 months of idle shelf life are presented for GIZO-based TFTs. The effects of oxygen partial pressure, annealing temperature and passivation are discussed. Optimized devices show highly stable properties, such as a recoverable ΔVT\<0.5 V after 24h of 1D=10 μA stress, quite promising for integration in electronic circuits.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79151474587\&partnerID=40\&md5=4900ca03bfb29d4bca3a2432ec6fdc1e}, author = {Barquinha, P., Pereira, L., Gon{\c c}alves, G., Martins, R., Fortunato, E.} } @conference {Barquinha20101376, title = {P-202L: Late-news poster: Long-term stability of oxide semiconductor-based TFTs}, booktitle = {Digest of Technical Papers - SID International Symposium}, volume = {41 1}, year = {2010}, note = {

cited By 0

}, pages = {1376-1379}, abstract = {

Long-term electrical stability measurements, including current/bias stress and aging over 18 months of idle shelf life are presented for GIZO-based TFTs. The effects of oxygen partial pressure, annealing temperature and passivation are discussed. Optimized devices show highly stable properties, such as a recoverable ΔV T\<0.5 V after 24h of I D=10 μA stress, quite promising for integration in electronic circuits. {\textcopyright} 2010 SID.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84863326353\&partnerID=40\&md5=29238e46ffc3f48e589b24444503e076}, author = {Barquinha, P., Pereira, L., Gon{\c c}alves, G., Martins, R., Fortunato, E.} } @conference {Martins2012, title = {P-type oxide-based thin film transistors produced at low temperatures}, booktitle = {Proceedings of SPIE - The International Society for Optical Engineering}, volume = {8263}, year = {2012}, note = {

cited By 2

}, abstract = {

P-type thin-film transistors (TFTs) using room temperature sputtered tin and copper oxide as a transparent oxide semiconductor have been produced on rigid and paper substrates. The SnO x films shows p-type conduction presenting a polycrystalline structure composed with a mixture of tetragonal β-Sn and α-SnO x phases, after annealing at 200{\textdegree}C. These films exhibit a hole carrier concentration in the range of ≈ 10 16-10 18 cm -3, electrical resistivity between 101-102 Ωcm, Hall mobility of 4.8 cm 2/Vs, optical band gap of 2.8 eV and average transmittance ≈ 85 \% (400 to 2000 nm). Concerning copper oxide Cu xO thin films they exhibit a polycrystalline structure with a strongest orientation along (111) plane. The Cu xO films produced between an oxygen partial pressure of 9 to 75\% showed p-type behavior, as it was measured by Hall effect and Seebeck measurements. The bottom gate p-type SnO x TFTs present field-effect mobility above 1.24 cm 2/Vs (including the paper p-type oxide TFT) and an on/off modulation ratio of 10 3 while the Cu xO TFTs exhibit a field-effect mobility of 1.3{\texttimes}10 -3 cm 2/Vs and an on/off ratio of 2{\texttimes}10 2. {\textcopyright} 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

}, doi = {10.1117/12.907387}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84858598530\&partnerID=40\&md5=e2a6403350a9f30a7a3360d9304eeff2}, author = {Martins, R.a , Figueiredo, V.a , Barros, R.a b , Barquinha, P.a , Gon{\c c}alves, G.a , Pereira, L.a , Ferreira, I.a , Fortunato, E.a} } @conference {Martins2013365, title = {Paper electronics: A challenge for the future}, booktitle = {Digest of Technical Papers - SID International Symposium}, volume = {44}, number = {1}, year = {2013}, note = {

cited By 0

}, pages = {365-367}, abstract = {

In this paper we report results concerning the use of paper as substrate and as an electronic component for the next generation of sustainable low cost electronic systems, where different examples of applications are given. {\textcopyright} 2013 Society for Information Display.

}, doi = {10.1002/j.2168-0159.2013.tb06222.x}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84905264459\&partnerID=40\&md5=c81f32ddc303d7dea7668b5a4486b9a9}, author = {Martins, R.a , Pereira, L.b , Fortunato, E.c} } @conference {Fortunato2009, title = {Paper field effect transistor}, booktitle = {Proceedings of SPIE - The International Society for Optical Engineering}, volume = {7217}, year = {2009}, note = {

cited By 2

}, abstract = {

In this paper we report the use of a sheet of cellulose fiber-based paper as the dielectric layer used in oxide based semiconductor thin film field-effect transistors (FETs). In this new approach we are using the cellulose fiber-based paper in an "interstate" structure since the device is build on both sides of the cellulose sheet. Such hybrid FETs present excellent operating characteristics such as high channel saturation mobility (\>30 cm 2/Vs), drain-source current on/off modulation ratio of approximately 104, near-zero threshold voltage, enhancement n-type operation and sub-threshold gate voltage swing of 0.8 V/decade. The cellulose fiber-based paper FETs characteristics have been measured in air ambient conditions and present good stability. The obtained results outpace those of amorphous Si TFTs and rival with the same oxide based TFTs produced on either glass or crystalline silicon substrates. The compatibility of these devices with large-scale/large-area deposition techniques and low cost substrates as well as their very low operating bias delineates this as a promising approach to attain high-performance disposable electronics like paper displays, smart labels, smart packaging, RFID and point-of-care systems for self analysis in bio-applications, among others. {\textcopyright} 2009 SPIE.

}, doi = {10.1117/12.816547}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67649227482\&partnerID=40\&md5=2b77ce3ec644b54f5c8049e854fcdaaf}, author = {Fortunato, E.a , Correia, N.a , Barquinha, P.a , Costa, C.a b , Pereira, L.a , Gon{\c c}alves, G.a , Martins, R.a} } @conference {Ferreira1999607, title = {Performances of nano/amorphous silicon films produced by hot wire plasma assisted technique}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {507}, year = {1999}, note = {

cited By 2

}, pages = {607-612}, abstract = {

This work reports on the performances of undoped and n doped amorphous/nano-crystalline silicon films grown by hot wire plasma assisted technique. The film{\textquoteright}s structure (including the presence of several nanoparticles with sizes ranging from 5 nm to 50 nm), the composition (oxygen and hydrogen content) and the transport properties are highly dependent on the filament temperature and on the hydrogen dilution. The undoped films grown under low r.f. power (≈4 mWcm-2) and with filament temperatures around 1850 {\textdegree}K have dark conductivities below 10-10 Scm-1, optical gaps of about 1.5 eV and photo-sensitivities above 105, (under AM1.5), with almost no traces of oxygen content. N-doped silicon films were also fabricated under the same conditions which attained conductivities of about 10-2 Scm-1.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032625047\&partnerID=40\&md5=3dca575a96ef9aaf9eb3d0996369d61c}, author = {Ferreira, I., Aguas, H., Mendes, L., Fernandes, F., Fortunato, E., Martins, R.} } @conference {Nunes2001152, title = {Performances presented by large area ZnO thin films deposited by spray pyrolysis}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {685}, year = {2001}, note = {

cited By 0

}, pages = {152-157}, abstract = {

In this work we present the results of a study on the uniformity of ZnO thin films produced by spray pyrolysis. The properties of the thin films depend essentially on the carrier gas pressure and gas flow used. The best films for optoelectronic applications were obtained with a carrier gas pressure of 2 bar and solution flow of 37 ml/min. The velocity of the nozzle affects essentially the uniformity of the ZnO thin films. However this important characteristic of the large area thin films is independent of the nature (doped and undoped) of the thin film and exhibits a high dependence on the variation of the temperature along the substrate. {\textcopyright} 2001 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34249915057\&partnerID=40\&md5=e8d580794f66866bee8f671853028acb}, author = {Nunes, P., Marques, A., Fortunato, E., Martins, R.} } @conference {Morawiec2014, title = {Photocurrent enhancement in thin a-Si:H solar cells via plasmonic light trapping}, booktitle = {Conference on Lasers and Electro-Optics Europe - Technical Digest}, volume = {2014-January}, year = {2014}, note = {

cited By 0

}, abstract = {

Photocurrent enhancement in thin a-Si:H solar cells due to the plasmonic light trapping is investigated, and correlated with the morphology and the optical properties of the selfassembled silver nanoparticles incorporated in the cells{\textquoteright} back reflector. {\textcopyright} 2014 Optical Society of America.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84944710757\&partnerID=40\&md5=d4d7c92e2521a3690c431616be559b0e}, author = {Morawiec, S.a b , Mendes, M.J.a , Filonovich, S.A.c , Mateus, T.c , Mirabella, S.a , Aguas, H.c , Ferreira, I.c , Simone, F.b ,} } @conference {{\'A}guas2003589, title = {Polymorphous Silicon Films Produced in Large Area Reactors by PECVD at 27.12 MHz and 13.56 MHz}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {762}, year = {2003}, note = {

cited By 0

}, pages = {589-594}, abstract = {

This work refers to a study performed on polymorphous silicon (pm-Si:H) at excitation frequencies of 13.56 and 27.12 MHz in a large area PECVD reactor. The plasma was characterised by impedance probe measurements, aiming to identify the plasma conditions that lead to produce pm-Si:H films. The films produced were characterised by spectroscopic ellipsometry, infrared and Raman spectroscopy and hydrogen exodiffusion experiments, which are techniques that permit the structural characterisation of the pm-Si films and to study the possible differences between the films deposited at 13.56 and 27.12 MHz. Conductivity measurements were also performed to determine the transport properties of the films produced. The set of data obtained show that the 27.12 MHz pm-Si:H can be grown at higher rates with less hydrogen dilution and power density, being the resulting films denser, chemically more stable and with improved performances than the pm-Si:H films grown at 13.56 MHz.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-1642479923\&partnerID=40\&md5=c9e1e90041218df50bd3b73ea82a77cc}, author = {{\'A}guas, H., Raniero, L., Pereira, L., Fortunato, E., Roca i Cabarrocas, P., Martins, R.} } @conference {Ferreira2001, title = {Porous silicon thin film gas sensor}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {664}, year = {2001}, note = {

cited By 0

}, pages = {A2671-A2676}, abstract = {

The performances of amorphous and nano-crystalline porous silicon thin films as gas detector are pioneer reported in this work. The films were produced by the hot wire chemical vapour deposition (HW-CVD). These films present a porous like-structure, which is due to the uncompensated bonds and oxidise easily in the presence of air. This behaviour is a problem when the films are used for solar cells or thin film transistors. For as gas detectors, the oxidation is a benefit, since the CO, H2 or O2 molecules replace the OH adsorbed group. In the present study we observe the behaviour of amorphous and nano-crystalline porous silicon thin films under the presence of ethanol, at room temperature. The data obtained reveal a change in the current values recorded by more than three orders of magnitude, depending on the film preparation condition. This current behaviour is due to the adsorption of the OH chemical group by the Si uncompensated bonds as can be observed in the infrared spectra. Besides that, the current response and its recover time are done in few seconds.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035558235\&partnerID=40\&md5=6f219c7c477104d1f39307faf9304506}, author = {Ferreira, I., Fortunato, E., Martins, R.} } @conference {Albarran2007231, title = {Preliminary budget methodology for reverse engineering applications using laser scanning}, booktitle = {Proceedings of the 3rd International Conference on Advanced Research in Virtual and Rapid Prototyping: Virtual and Rapid Manufacturing Advanced Research Virtual and Rapid Prototyping}, year = {2007}, note = {

cited By 1

}, pages = {231-235}, abstract = {

The driving force behind the work herein presented is the importance of budgeting in a competitive market. The problem at hands is the creation of a budgeting methodology for reverse engineering applications, involving laser scanning, that has the ability to generate budgets for different customer accuracy requirements and for parts of different morphologic characteristics, such as: shape, dimension and/or detail complexity. A breakup approach was used to implement the methodology: the reverse engineering process was broken in nine basic identified steps and elementary sources of cost were defined at the different reverse engineering stages as well. Particular budgeting methodologies for each step of the process were created. The obtained results so far point to the possibility of creating a complete budgeting system based on the proposed methodology. {\textcopyright} 2008 Taylor \& Francis Group.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-75049084900\&partnerID=40\&md5=8897fc64bbe29ba90f7f0d399827b074}, author = {Albarran, T., Lopes, L., Cabe{\c c}a, J., Martins, R.F., Mour{\~a}o, A.J.F.} } @conference {Ferreira2001, title = {Properties of nano-crystalline n-type silicon films produced by hot wire plasma assisted technique}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {664}, year = {2001}, note = {

cited By 1

}, pages = {A761-A766}, abstract = {

In this work, we present the properties of n-type silicon films obtained by hot wire plasma assisted technique produced at different rf power and gas flow rate. The films were produced at a filament temperature of 2000{\textdegree}C and the rf power was varied from 0 W to 200 W while gas flow rate was varied from 15 to 100 sccm keeping rf power at 50 W. In this flow rate range, the growth rate of the films varied from 5{\r A}/s to 250{\r A}/s and the corresponding electrical room dark conductivity varied from 10-2 to 10(Ωcm)-1. On the other hand, we observed that the electrical conductivity increased from 2 to 6(Ωcm)-1, and the Hall mobility from 0.1 to 2 cm2/V.s as rf power change from 0 W to 200 W. The infrared, EDS and XPS analyses revealed the existence of oxygen incorporation, which is not related to post-deposition oxidation. The X-ray diffraction and μRaman data show the presence of Si crystals in the films structure and the SEM micrographs reveal a granular surface morphology with grain sizes lower than 60 nm.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035556743\&partnerID=40\&md5=3c8006f9bc15d6e529b7372816e69259}, author = {Ferreira, I., Fernandes, F.B., Vilarinho, P., Fortunato, E., Martins, R.} } @conference {Nunes2001128, title = {Properties of ZnO thin films deposited by spray pyrolysis and magnetron sputtering}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {685}, year = {2001}, note = {

cited By 1

}, pages = {128-133}, abstract = {

In this work we present a study of the properties of ZnO thin films produced by spray pyrolysis and r.f. magnetron sputtering. Before the annealing treatment the properties of the films are very similar, which means that the films produced by both techniques could be used on optoelectronic devices. However spray pyrolysis is a more simple and cheap technique than sputtering, but with this last technique the thin films exhibit a higher uniformity. {\textcopyright} 2001 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34249877422\&partnerID=40\&md5=97b5d9d9946f29c6479c64d1dc07490c}, author = {Nunes, P., Fortunato, E., Martins, R.} } @conference {Martins1985722, title = {ROLE OF I. T. O. LAYER ON THE PERFORMANCES OF AMORPHOUS SILICON SOLAR CELLS PRODUCED IN A TWO CONSECUTIVE DECOMPOSITION AND DEPOSITION CHAMBER SYSTEM.}, booktitle = {Commission of the European Communities, (Report) EUR}, year = {1985}, note = {

cited By 0

}, pages = {722-726}, abstract = {

Amorphous Silicon solar cells have been produced by a two consecutive decomposition and deposition chamber system, using polished S. S. substrates. Through a systematic investigation of the electrical and optical properties of doped and undoped amorphous silicon layers (1) we observe that the deposition conditions (gas partial pressure, density of r. f. power, substrate temperature, electromagnetic static fields applied to the substrate, and gas flow rate) influence films properties. In the course of this investigation we have been studying the role of the sheet resistance, R//s, of the I. T. O. layer on the short circuit current, I//s//c, and on the open circuit voltage, V//o//c, of p. i. n. structures of 16cm**2 in area. The obtained results indicate that V//o//c is almost independent on R//s, while I//s//c variation approaches a square root dependence on R//s.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022233458\&partnerID=40\&md5=5410914e0c1922d39b0228c2ccb9afb2}, author = {Martins, R., Guimaraes, L., Carvalho, N.} } @conference {Vieira1993637, title = {Role of photodegradation on the μτ product and microstructure of the a-Si:H pin devices}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {297}, year = {1993}, note = {

cited By 3

}, pages = {637-642}, abstract = {

PIN solar cells were light soaked up to 60 hours. The cell characteristics, the optoelectronic properties and the microstructure parameter (R = I2100/I2100+I2000) as well as the hydrogen content (CH) and density of states (g(Ef)) of the active i-layer were monitored throughout the entire light induced degradation process and compared with the correspondents μτ product (for both carriers) inferred through steady photoconductivity and FST measurements. Data show a strong correlation between the decrease of μτ product for electron and the increase of the fraction of hydrogen bonded on internal surfaces (R increases from 0.1 to 0.4) suggesting structural changes during the light induced defects{\textquoteright} formation. For holes, the μτ product remains approximately constant and only dependent on the initial hydrogen content. As g(Ef) increases, μτ presents an asymmetrical decrease showing that electrons are more sensitive to defects{\textquoteright} growth than holes. We also observe that the rate of degradation is faster for samples having the lowest defect densities, R and CH, showing that the amount of degradation is not a simple function of the photon exposure (Gt product) but also depends on the material microstructure.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027847308\&partnerID=40\&md5=718f331e948301f9d326923f7ea4f47a}, author = {Vieira, M., Fortunato, E., Lavareda, G., Carvalho, C.N., Martins, R.} } @conference {Fortunato1999303, title = {Role of the collecting resistive layer on the static characteristics of 2D a-Si:H thin film position sensitive detector}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {507}, year = {1999}, note = {

cited By 0

}, pages = {303-308}, abstract = {

The aim of this work is to present an analytical model able to interpret the role of the thin collecting resistive layer on the static performances exhibited by 2D amorphous silicon hydrogenated pin thin film position sensitive detectors. In addition, experimental results concerning the device linearity and spatial resolution are presented and checked against the predicted values of the analytical model proposed.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032625451\&partnerID=40\&md5=7c7725f9ec9d0a1d0b3bd67c618f2a16}, author = {Fortunato, E., Martins, R.} } @conference {Martins1997609, title = {Role of the gas flow parameters on the uniformity of films produced by PECVD technique}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {467}, year = {1997}, note = {

cited By 0

}, pages = {609-614}, abstract = {

The aim of this work is to present an analytical model able to interpret the experimental data of the dependence of film{\textquoteright}s uniformity on the discharge pressure, gas flow and temperature used during the production of thin films by the plasma enhancement chemical vapour deposition technique, under optimised electrode{\textquoteright}s geometry and electric field distribution. To do so, the gas flow is considered to be quasi-incompressible and inviscous leading to the establishment of the electro-fluid-mechanics equations able to interpret the film{\textquoteright}s uniformity over the substrate area, when the discharge process takes place in the low power regime.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031351337\&partnerID=40\&md5=59531f93f677b19b46db481bd5c769e0}, author = {Martins, R., Macarico, A., Ferreira, I., Fortunato, E.} } @conference {Martins1994587, title = {Role of the lateral leakage current on amorphous silicon solar cells}, booktitle = {Conference Record of the IEEE Photovoltaic Specialists Conference}, volume = {1}, year = {1994}, note = {

cited By 0

}, pages = {587-590}, abstract = {

The aim of this work is to interpret the role of the lateral leakage current on the a-Si:H solar cell performances (J-V characteristics, responsivity and the apparent device degradation behaviour), under low illumination conditions.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028706870\&partnerID=40\&md5=eacbd6126871d492c8203e30f048fee3}, author = {Martins, Rodrigo, Fortunato, Elvira, Bicho, Ana, Lavareda, Guilherme} } @conference {Aguas2007415, title = {Role of the oxide layer on the performances of a-Si:H schottky structures applied to PDS fabrication}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {910}, year = {2007}, note = {

cited By 0

}, pages = {415-420}, abstract = {

In this work we present results of studies performed on Schottky and metal-insulator-semiconductor (MIS) position sensitive detectors (PSD) structures: substrate (glass)/ Cr (300 nm) / a-Si:H [n] (37 nm) / a-Si:H [i] (600 nm) / SiO2 (1.5 nm - for the MIS) / Au (7 nm). The effect of the interfacial oxide layer between Au and a-Si:H, for the MIS structures, was studied and compared with the Schottky, in order to determine how beneficial it could be for device performances and time degradation. For doing so, the Au thickness of 70{\r A} was deposited by thermal evaporation on an oxide free (Schottky) and oxidized (≈20{\r A}) (MIS) a-Si:H surfaces. These structures were characterized by SIMS, RBS, SEM and AFM in order to correlate the obtained diffusion profile of Au at the interface and the topography with the presence of the oxide at the interface. The results show that the Au inter-diffuses very easily in the oxide free a-Si:H surface, even at room temperature, degrading the devices performance. On the other hand, the MIS structures, with their interfacial oxide present no structural changes after annealing and the PSD produced are stable. We believe that this effect is associated with the barrier effect of the interfacial oxide that prevents the Au diffusion. The optimized 1D MIS sensors are stable and exhibit a linearity error as low as 0.8 \% and sensitivities of 33 mV/cm for a 5 mW spot beam intensity at a wavelength of 532 nm, while the Schottky sensors showed a time degradation of their characteristics. {\textcopyright} 2006 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34249931890\&partnerID=40\&md5=43bac7c8e831a40816967c31740968f5}, author = {Aguas, H., Pereira, L., Costa, D., Raniero, L., Fortunato, E., Martins, R.} } @conference {Martins199455, title = {Silicon oxycarbide microcrystalline layers produced by spatial separation techniques}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {336}, year = {1994}, note = {

cited By 3

}, pages = {55-60}, abstract = {

Silicon oxycarbide microcrystallinc layers, n- and p-doped, highly conductive and highly transparent have been produced using a Two Consecutive Decomposition and Deposition Chamber (TCDDC) system. The films exhibit suitable properties for optoelectronic applications where wide band gap materials with required conductivity and stability are needed. In this paper we present the role of partial oxygen pressure (po2) in controlling the composition, structure and transport properties (conductivity. δd and optical gap, Eop) of silicon oxycarbide microcrystalline layers. {\textcopyright} 1994 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897585030\&partnerID=40\&md5=69b8e4aa230bcaa78eaf31e273ed6625}, author = {Martins, R.a , Ferreira, I.a , Fortunato, E.a , Vieira, M.b} } @conference {Martins1995745, title = {Simulation of the lateral photo effect in large-area 1D a-Si:H p-i-n thin-film position-sensitive detectors}, booktitle = {Proceedings of SPIE - The International Society for Optical Engineering}, volume = {2397}, year = {1995}, note = {

cited By 0

}, pages = {745-756}, abstract = {

The aim of this work is to provide the basis for the interpretation, under steady state, of the lateral photoeffect in p-i-n a-Si:H 1D Thin Film Position Sensitive Detectors (1D TFPSD) through an analytical model. The experimental data recorded in 1D TFPSD devices with different performances are compared with the predicted curves and the obtained correlation{\textquoteright}s discussed.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029222262\&partnerID=40\&md5=75ca0c14b0467a673cbaf49761c4fa51}, author = {Martins, Rodrigo, Fortunato, Elvira} } @conference {Ferreira2015647, title = {SnO2 thin Film Oxides Produced by rf Sputtering for Transparent Thermoelectric Devices}, booktitle = {Materials Today: Proceedings}, volume = {2}, number = {2}, year = {2015}, note = {

cited By 0

}, pages = {647-653}, abstract = {

The combination of high transparency and good thermoelectric properties of SnO2 can open new field of applications for the thin film thermoelectric materials. Here we report on SnO2 thin films with transmittance above 90\%, resistivity bellow 10-3Ωm and a Power Factor around 10-4 W/m.K2, for a Seebeck of -255μV/K, at room temperature. The effect of film thickness and post-deposition annealing on the thermoelectric properties were analysed. The performances of a single layer thermoelectric device are also presented. {\textcopyright} 2015 .

}, doi = {10.1016/j.matpr.2015.05.090}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84947732704\&partnerID=40\&md5=0588d4642ff84b323dbdad362a58e2b9}, author = {Ferreira, M., Loureiro, J., Nogueira, A., Rodrigues, A., Martins, R., Ferreira, I.} } @conference {Elangovan200692, title = {Some studies on molybdenum doped indium oxide thin films rf sputtered at room temperature}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {928}, year = {2006}, note = {

cited By 1

}, pages = {92-97}, abstract = {

Thin films of molybdenum doped indium oxide (IMO) were rf sputtered onto glass substrates at room temperature. The films were studied as a function of oxygen volume percentage (OVP) ranging 1.4 - 10.0\% in the sputtering chamber. The thickness of the films found varying between 180 and 260 nm. The X-ray diffraction pattern showed the films are polycrystalline with the peaks corresponding to (222) and (400) planes and one among them showing as a preferential orientation. It is observed that the preferred orientation changes from (222) plane to (400) as the OVP increases from 1.4 to 10.0\%. The transmittance spectra were found to be in the range of 77 to 89\%. The optical band gap calculated from the absorption coefficient of transmittance spectra was around 3.9 eV. The negative sign of Hall coefficient confirmed the films were n-type conducting. The bulk resistivity increased from 2.26{\texttimes}10 -3 to 4.08{\texttimes}-1 Ωcm for the increase in OVP from 1.4 to 4.1\%, and thereafter increased dramatically so as the Hall coefficients were not detectable. From the AFM morphologies it is evaluated that the RMS roughness of the films ranges from 0.9 to 3.2 nm. {\textcopyright} 2006 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33947670593\&partnerID=40\&md5=ca2fb785118b2df1a1ee5e0fcf85e0a7}, author = {Elangovan, E.a , Barquinha, P.a , Pimental, A.a , Viana, A.S.b , Martins, R.a , Fortunato, E.a} } @conference {Fantoni1995695, title = {Spatial microscopic/macroscopic control and modeling of the p.i.n devices stability}, booktitle = {Proceedings of SPIE - The International Society for Optical Engineering}, volume = {2397}, year = {1995}, note = {

cited By 0

}, pages = {695-702}, abstract = {

The introduction into a traditional p.i.n. structure of two defective buffer layers near the p/i and i/n interfaces can improve the device stability and efficiency through an enhancement of the electric field profile at the interfaces and a reduction of the available recombination bulk centers. The defectous layer ({\textquoteleft}i-layer{\textquoteright}), grown at a higher power density, present a high density of the defects and acts as {\textquoteleft}gettering centers{\textquoteright} able to tailor light induced defects under degradation conditions. If the i-layer density of states remains below 1016 eV-1 cm-3 and assuming a Gaussian distribution of defect states, the gettering center distribution will not affect significantly the carrier population but only its spatial distribution. We report here about a device numerical simulation that allows us to analyze the influence of the {\textquoteleft}i- layer{\textquoteright} position, thickness and density of states on the a-Si:H solar cells performances. Results of some systematic simulation rom the ASCA program (Amorphous Solar Cell Analysis), and for different configurations will be presented.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029237975\&partnerID=40\&md5=1a84365631e3349bd62f802614828553}, author = {Fantoni, Alessandro, Vieira, Manuela, Martins, Rodrigo} } @conference {Malik199747, title = {Spray-deposited metal oxide films with various properties for micro- and optoelectronic applications: Growth and characterization}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {471}, year = {1997}, note = {

cited By 1

}, pages = {47-52}, abstract = {

This work reports the structure and electro-optical characteristics of different metal oxide films obtained by spray pyrolysis on heated glass substrates, aiming their application in optoelectronic devices. The results show that this technique leads to thin films with properties ranging from dielectric to degenerate semiconductors, offering the following advantages: simplicity, low cost, high productivity and the possibility of covering large areas, highly important for large area device applications.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030673446\&partnerID=40\&md5=706e127ff648b87e854dd8ec86b9b6b5}, author = {Malik, A., Seco, A., Nunes, R., Vieira, M., Fortunato, E., Martins, R.} } @conference {Amor{\'\i}n200543, title = {Structural and electrical characterization of ferroelectric SrBi 2Nb2O9 single crystals grown by high-temperature self-flux solution}, booktitle = {Ferroelectrics}, volume = {320}, year = {2005}, note = {

cited By 3

}, pages = {43-50}, abstract = {

High-quality SrBi2Nb2O9 (SBN) single crystals were grown from a melt using a high-temperature self-flux solution method and Bi2O3 added with B2O3 as a flux. A suitable thermal profile involving slow cooling rates allowed growing large and translucent SBN crystals exhibiting platelet morphology with typical size \~{}5 {\texttimes} 5 mm2 and thickness approximately 400 μm. X-ray diffraction revealed a dominant (001)-orientation of the major face of the platelet crystals and edges oriented parallel to the [110] directions. The dielectric properties were evaluated along the ab-plane and in the c-axis direction. The ferro-paraelectric phase transition was observed at TC = 440{\textdegree}C with Curie-Weiss relationship above TC. The anisotropy of dielectric permittivity, i.e., the ratio between permittivity in the ab-plane and along c-axis was about 10 at TC-The obtained results are used to discuss the observed correlations between anisotropy, crystalline orientation, and electrical properties.

}, doi = {10.1080/00150190590966775}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33749466131\&partnerID=40\&md5=75269d8233f082df62e7b952639853dd}, author = {Amor{\'\i}n, H.a , Martins, R.S.a b , Kholkin, A.L.a , Costa, M.E.V.a} } @conference {Willeke1988320, title = {Structural properties of weakly absorbing highly conductive SiC thin films prepared in a TCDDC system}, booktitle = {Conference Record of the IEEE Photovoltaic Specialists Conference}, volume = {1}, year = {1988}, note = {

cited By 1

}, pages = {320-323}, abstract = {

Diffraction and other structural measurements on n-type SiC thin films prepared in a TCDDC (two consecutive decomposition and deposition chamber) system indicate the presence of Si microcrystals (without evidence for SiC crystallites). Weakly absorbing, highly conductive layers (σ >= 10-1 (Ω-cm)-1) contain up to 20 at.\% C and 25 at.\% O. The optoelectronic properties of these films can be explained in terms of a sufficient volume fraction (above the percolation threshold) of Si microcrystals surrounded by an a-Si:C:O:H matrix.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024180821\&partnerID=40\&md5=8add267f5f87cc851e3878917ba92090}, author = {Willeke, G., Martins, R.} } @conference {Martins1995787, title = {Structure and composition of doped silicon oxycarbide microcrystalline layers produced by spatial separation techniques}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {358}, year = {1995}, note = {

cited By 0

}, pages = {787-792}, abstract = {

This work presents experimental data concerning the role of the oxygen partial pressure used during the preparation process, on the structure, composition and optoelectronic properties of wide band gap doped microcrystalline silicon oxycarbide films produced by a TCDDC system [1].

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029213002\&partnerID=40\&md5=0b4d6836ada3da7a403d03ffcd597c41}, author = {Martins, R., Vieira, M., Ferreira, I., Fortunato, E.} } @conference {Raniero20051548, title = {Study of a-SiC:H buffer layer on nc-Si/a-Si:H solar cells deposited by PECVD technique}, booktitle = {Conference Record of the IEEE Photovoltaic Specialists Conference}, year = {2005}, note = {

cited By 0

}, pages = {1548-1551}, abstract = {

This work deals with the study of the role of the buffer layers thickness on the TCO/p-a-SiC:H/buffer1/buffer2/i(nc-Si/a-Si:H)/n-a- Si:H/Al solar cell I-V and impedance performances. The aim was to improve the p/i interface region, which has a large influence on the solar cell characteristics and stability. In order to match the difference between the p and i layers optical gaps, the buffer layers were deposited using, for each layer, different methane to silane mixtures, aiming to obtain a gradual match of the corresponding optical gaps. The intrinsic layer was deposited at high hydrogen dilution rates at 27.12 MHz in conditions that allowed the incorporation of nanoparticles/nanoclusters. Solar cells with fill factor of 0.63; open circuit voltage of 0.93 Volts; short circuit current density of 16.13 mA/cm2 and an efficiency of 9.4\% were produced with buffer layers around 1.3 nm thick. When comparing these solar cells with conventional amorphous silicon solar cells we notice that the quantum efficiency from ultraviolet to green regions is improved up to 13\%, in average. Concerning solar cell capacitance, the data show that the best solar cells exhibit the highest capacitance, meaning that the films are compact and dense, in-line with the other electrical characteristics obtained. {\textcopyright}2005 IEEE.

}, doi = {10.1109/PVSC.2005.1488439}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-27944483777\&partnerID=40\&md5=66c9828ee0aa7a642d7dd1cb216a5bd5}, author = {Raniero, L., Ferreira, I., {\'A}guas, H., Zhang, S., Fortunato, E., Martins, R.} } @conference {Meng1995379, title = {Study of annealed indium tin oxide films prepared by rf reactive magnetron sputtering}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {388}, year = {1995}, note = {

cited By 1

}, pages = {379-384}, abstract = {

Tin doped indium oxide (ITO) films were deposited on glass substrates by rf reactive magnetron sputtering using a metallic alloy target (In-Sn, 90-10). The post-deposition annealing has been done for ITO films in air and the effect of annealing temperature on the electrical, optical and structural properties of ITO films was studied. It has been found that the increase of the annealing temperature will improve the film electrical properties. The resistivity of as-deposited film is about 1.3{\texttimes}10-1 Ω* cm and decreases down to 6.9{\texttimes}10-3 Ω* cm as the annealing temperature is increased up to 500{\textdegree}C. In addition, the annealing will also increase the film surface roughness which can improve the efficiency of amorphous silicon solar cells by increasing the amount of light trapping.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029481527\&partnerID=40\&md5=46e8d9d02c6a07714e3bdd851401d9a0}, author = {Meng, L., Macarico, A., Martins, R.} } @conference {Nunes2001, title = {Thin film combustible gas sensors based on zinc oxide}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {666}, year = {2001}, note = {

cited By 0

}, pages = {F521-F526}, abstract = {

Sensitivity tests to reductive gases such as methane, hydrogen and ethane were performed on zinc oxide (ZnO) thin films. The highest value of sensitivity was obtained for the film with a high electrical resistivity and a low thickness. The variation of the operating temperature of the film leads to a significant change in the sensitivity of the sensor with an ideal operating temperature dependence of the gas used. The sensitivity of the ZnO thin films changes linear with the increase of the gas concentration. However these films seem to be more appropriated for the detection of hydrogen following by methane and than for ethane since the value of sensitivity obtained are higher and its variation with the gas concentration more pronounced.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035556498\&partnerID=40\&md5=3daf52b78503ee601674e94be88b110e}, author = {Nunes, P., Fortunato, E., Martins, R.} } @conference {Fortunato2001146, title = {Thin film metal oxide semiconductors deposited on polymeric substrates}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {685}, year = {2001}, note = {

cited By 0

}, pages = {146-151}, abstract = {

Highly textured transparent conducting ZnO:Al thin films have been prepared by r.f. magnetron sputtering. The films were deposited on polyester (Mylar type D, 100 μm thickness) and glass substrates at room temperature. Surface stylus profiling, X-ray diffraction, scanning electron microscopy, transmission electron microscope and Hall effect measurements as a function of temperature, using the van der Pauw technique have characterized the films. The samples are polycrystalline with a hexagonal wurtzite structure and a strong crystallographic c-axis orientation (002) perpendicular to the substrate surface (columnar structure). The ZnO:Al thin films with a resistivity as low as 3.6{\texttimes}10-2 Ωcm have been obtained, as deposited. {\textcopyright} 2001 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34249894185\&partnerID=40\&md5=94f90527bf9fda27a5836d6af67bbd1c}, author = {Fortunato, E.a , Nunes, P.a , Marques, A.a , Costa, D.a , {\'A}guas, H.a , Ferreira, I.a , Costa, M.E.V.b , Martins, R.a} } @conference {Fortunato2001, title = {Thin film metal oxide semiconductors deposited on polymeric substrates}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {666}, year = {2001}, note = {

cited By 0

}, pages = {F1131-F1136}, abstract = {

Highly textured transparent conducting ZnO:Al thin films have been prepared by r.f. magnetron sputtering. The films were deposited on polyester (Mylar type D, 100 μm thickness) and glass substrates at room temperature. Surface stylus profiling, X-ray diffraction, scanning electron microscopy, transmission electron microscope and Hall effect measurements as a function of temperature have been used to characterize the produced films. The samples are polycrystalline with a hexagonal wurtzke structure and a strong crystallographic c-axis orientation (002) perpendicular to the substrate surface (columnar structure). The ZnO:Al thin films with a resistivity as low 3.6{\texttimes}10-2 Ωcm have been obtained, as deposited.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035556455\&partnerID=40\&md5=fafda128374e389f2e8a44710c52c895}, author = {Fortunato, E., Nunes, P., Marques, A., Costa, D., {\'A}guas, H., Ferreira, I., Costa, M.E.V., Martins, R.} } @conference {Bahubalindruni2014582, title = {Transparent current mirrors using A-GIZO TFTs: Simulation with RBF models and fabrication}, booktitle = {Proceedings - UKSim-AMSS 16th International Conference on Computer Modelling and Simulation, UKSim 2014}, year = {2014}, note = {

cited By 0

}, pages = {582-586}, abstract = {

This paper analyzes transparent two-TFT current mirrors using a-GIZO TFTs with different mirroring ratios. In order to achieve a high mirroring ratio, the output TFT in the circuit employed a fingered structure layout to minimize area and overlap capacitance. The analysis of the current mirrors is performed in three phases. In the first, a radial basis function based (RBF) model is developed using measured data from fabricated TFTs on the same chip. Then, in the second phase, the RBF model is implemented in Verilog-A that is used to simulate two-TFT current mirrors with different mirroring ratios. The simulations are carried out using Cadence spectre simulator. In the third phase, simulation results are validated with the measured response from the fabricated circuits. {\textcopyright} 2014 IEEE.

}, doi = {10.1109/UKSim.2014.98}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84926638107\&partnerID=40\&md5=ff9862027bdb9abc383fd6d363f4fa18}, author = {Bahubalindruni, P.a , Tavares, V.a , Duarte, C.a , Cardoso, N.a , Oliveira, P.a , Barquinha, P.b , Martins, R.b , Fortunato, E.b} } @conference {Martins1994508, title = {Transport properties of doped silicon oxycarbide microcrystalline films produced by spatial separation techniques}, booktitle = {Conference Record of the IEEE Photovoltaic Specialists Conference}, volume = {1}, year = {1994}, note = {

cited By 0

}, pages = {508-511}, abstract = {

This paper presents results of the role of the oxygen partial pressure (pO2) used on the properties exhibited by doped μc silicon oxycarbide films produced by a Two Consecutive Decomposition and Deposition Chamber (TCDDC) system [1], where a spatial separation between the plasma and the growth regions is achieved. The films produced are highly conductive and transparent with suitable properties for optoelectronic applications.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028724235\&partnerID=40\&md5=8131d07866d54409b3eb85ae64005df2}, author = {Martins, Rodrigo, Vieira, Manuela, Ferreira, Isabel, Fortunato, Elvira, Guimaraes, L.} } @conference {{\'A}guas2000179, title = {Two step process for the growth of a thin layer of silicon dioxide for tunnelling effect applications}, booktitle = {Materials Research Society Symposium - Proceedings}, volume = {619}, year = {2000}, note = {

cited By 0

}, pages = {179-184}, abstract = {

In today{\textquoteright}s main crystalline silicon (c-Si) applications in MOS (metal-oxide-silicon), MIS (metal-insulator-semiconductor) or SIS (Semiconductor-Insulator-Semiconductor), the growing of the oxide layer plays the main role, dictating the device performances, in particular if it has to be grown by a low temperature process. Of fundamental importance is the SiO2 interface with the c-Si. A very low defect density interface is desirable so that the number of trapping states can be reduced and the devices performance optimised. A two step low temperature oxidation process is proposed. The process consists of growing first a layer of oxide by a wet process and then treating the grown oxide with an oxygen plasma. The oxygen ions from the plasma bombard the oxide causing compaction of the oxide and a decrease in the interface roughness and defect density. Infrared spectroscopy and spectroscopic ellipsometry measurements were performed on the samples to determine the oxide thickness, optical and structural properties. SIS structures were built and capacitance measurements were performed under dark and illuminated conditions from which were inferred the interface defect density and correlated with the oxide growth process.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034447391\&partnerID=40\&md5=007a6a2494c51c54df85049eab3020f2}, author = {{\'A}guas, H., Cabrita, A., Tonello, P., Nunes, P., Fortunato, E., Martins, R.} } @conference {Martins2009, title = {Zinc oxide and related compounds: Order within the disorder}, booktitle = {Proceedings of SPIE - The International Society for Optical Engineering}, volume = {7217}, year = {2009}, note = {

cited By 0

}, abstract = {

This paper discusses the effect of order and disorder on the electrical and optical performance of ionic oxide semiconductors based on zinc oxide. These materials are used as active thin films in electronic devices such as pn heterojunction solar cells and thin-film transistors. Considering the expected conduction mechanism in ordered and disordered semiconductors the role of the spherical symmetry of the s electron conduction bands will be analyzed and compared to covalent semiconductors. The obtained results show p-type c-Si/a-IZO/poly-ZGO solar cells exhibiting efficiencies above 14\% in device areas of about 2.34 cm2. Amorphous oxide TFTs based on the Ga-Zn-Sn-0 system demonstrate superior performance than the polycrystalline TFTs based on ZnO, translated by ION/IOFF ratio exceeding 107, turn-on voltage below 1-2 V and saturation mobility above 25 cm2/Vs. Apart from that, preliminary data on p-type oxide TFT based on the Zn-Cu-O system will also be presented. {\textcopyright} 2009 SPIE.

}, doi = {10.1117/12.816577}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67649159066\&partnerID=40\&md5=235f0dc16c805814866ce474933e809c}, author = {Martins, R., Pereira, L., Barquinha, P., Ferreira, I., Prabakaran, R., Gon{\c c}alves, G., Gon{\c c}alves, A., Fortunato, E.} } @conference {Fortunato2001140, title = {Zinc oxide thin films deposited by rf magnetron sputtering on mylar substrates at room temperature}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {685}, year = {2001}, note = {

cited By 0

}, pages = {140-145}, abstract = {

Aluminium doped zinc oxide thin films (ZnO:Al) have been deposited on polyester (Mylar type D, 100 μm thickness) substrates at room temperature by r.f. magnetron sputtering. The structural, morphological, optical and electrical properties of the deposited films have been studied. The samples are polycrystalline with a hexagonal wurtzite structure and a strong crystallographic c-axis orientation (002) perpendicular to the substrate surface. The ZnO:Al thin films with 85\% transmittance in the visible and infra-red region and a resistivity as low as 3.6{\texttimes}102 Ωcm have been obtained, as deposited. The obtained results are comparable to those ones obtained on glass substrates, opening a new field of low cost, light weight, small volume, flexible and unbreakable large area optoelectronic devices. {\textcopyright} 2001 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34249915302\&partnerID=40\&md5=556d33a67ac882e89c28a174826ee775}, author = {Fortunato, E.a , Nunes, P.a , Marques, A.a , Costa, D.a , {\'A}guas, H.a , Ferreira, I.a , Costa, M.E.V.b , Martins, R.a} } @conference {Pimentel2006243, title = {Zinc oxide thin films used as an ozone sensor at room temperature}, booktitle = {Materials Research Society Symposium Proceedings}, volume = {915}, year = {2006}, note = {

cited By 2

}, pages = {243-248}, abstract = {

In this paper we present results of intrinsic/non doped zinc oxide films deposited at room temperature by rf magnetron sputtering able to be used as a truly semiconductor on electronic devices like ozone gas sensors and ultra-violet detectors. The produced films are polycrystalline with a c-axis preferential orientation parallel to the substrate. The films{\textquoteright} resistivity varies from 4.0{\texttimes}10-2 Ωcm to 1.0{\texttimes}10-9 Ωcm, depending on the deposition conditions used (rf power density and oxygen partial pressure), which turns not affecting the optical properties (in average a transmittance of around 85 \% and an optical band gap of about 3.44 eV, independent of the deposition conditions used). When exposed to UV light the sensor response based on these films may exceed more than 5 orders of magnitude, recovering to the initial state in the presence of ozone. The sensitivity of the films is improved when the oxygen partial pressure increases and the rf power density used decreases, due to changes on the structural properties of the films. {\textcopyright} 2006 Materials Research Society.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33749374762\&partnerID=40\&md5=91938673d9ffead98d8bd45791d01b24}, author = {Pimentel, A.C., Gon{\c c}alves, A., Marques, A., Martins, R., Fortunato, E.} } @article {Lorenz2016, title = {The 2016 oxide electronic materials and oxide interfaces roadmap}, journal = {Journal of Physics D: Applied Physics}, volume = {49}, number = {43}, year = {2016}, note = {

cited By 0

}, abstract = {

Oxide electronic materials provide a plethora of possible applications and offer ample opportunity for scientists to probe into some of the exciting and intriguing phenomena exhibited by oxide systems and oxide interfaces. In addition to the already diverse spectrum of properties, the nanoscale form of oxides provides a new dimension of hitherto unknown phenomena due to the increased surface-to-volume ratio. Oxide electronic materials are becoming increasingly important in a wide range of applications including transparent electronics, optoelectronics, magnetoelectronics, photonics, spintronics, thermoelectrics, piezoelectrics, power harvesting, hydrogen storage and environmental waste management. Synthesis and fabrication of these materials, as well as processing into particular device structures to suit a specific application is still a challenge. Further, characterization of these materials to understand the tunability of their properties and the novel properties that evolve due to their nanostructured nature is another facet of the challenge. The research related to the oxide electronic field is at an impressionable stage, and this has motivated us to contribute with a roadmap on {\textquoteright}oxide electronic materials and oxide interfaces{\textquoteright}. This roadmap envisages the potential applications of oxide materials in cutting edge technologies and focuses on the necessary advances required to implement these materials, including both conventional and novel techniques for the synthesis, characterization, processing and fabrication of nanostructured oxides and oxide-based devices. The contents of this roadmap will highlight the functional and correlated properties of oxides in bulk, nano, thin film, multilayer and heterostructure forms, as well as the theoretical considerations behind both present and future applications in many technologically important areas as pointed out by Venkatesan. The contributions in this roadmap span several thematic groups which are represented by the following authors: novel field effect transistors and bipolar devices by Fortunato, Grundmann, Boschker, Rao, and Rogers; energy conversion and saving by Zaban, Weidenkaff, and Murakami; new opportunities of photonics by Fompeyrine, and Zuniga-Perez; multiferroic materials including novel phenomena by Ramesh, Spaldin, Mertig, Lorenz, Srinivasan, and Prellier; and concepts for topological oxide electronics by Kawasaki, Pentcheva, and Gegenwart. Finally, Miletto Granozio presents the European action {\textquoteright}towards oxide-based electronics{\textquoteright} which develops an oxide electronics roadmap with emphasis on future nonvolatile memories and the required technologies. In summary, we do hope that this oxide roadmap appears as an interesting up-to-date snapshot on one of the most exciting and active areas of solid state physics, materials science, and chemistry, which even after many years of very successful development shows in short intervals novel insights and achievements. Guest editors: M S Ramachandra Rao and Michael Lorenz. {\textcopyright} 2016 IOP Publishing Ltd.

}, doi = {10.1088/0022-3727/49/43/433001}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992395868\&partnerID=40\&md5=c4c21b5579a87a37f490b2b1f349931f}, author = {Lorenz, M.a , Ramachandra Rao, M.S.b , Venkatesan, T.c , Fortunato, E.d , Barquinha, P.d , Branquinho, R.d , Salgueiro, D.d , Ma} } @article {{\'A}guas20077530, title = {3 dimensional polymorphous silicon based metal-insulator-semiconductor position sensitive detectors}, journal = {Thin Solid Films}, volume = {515}, number = {19 SPEC. ISS.}, year = {2007}, note = {

cited By 2

}, pages = {7530-7533}, abstract = {

In this work we investigate the properties of a polymorphous silicon (pm-Si:H) metal-insulator-semiconductor (MIS) structure used in 3D position sensitive detectors (PSD). For the first time a 3D sensor made-up by pm-Si:H/SiO2/Au layers is presented. MIS structures present several advantages over p-i-n structures, such as easier fabrication, fast response time and higher resolution. The 1D MIS PSD that constitute the array were extensively studied aiming its application in 3D pattern recognition. The results obtained show that MIS PSD can achieve non-linearities below 2\% and sensitivities of 3.2~μA/cm over 6~mm length sensors. The miniaturization of the sensors length to arrays of 6 and 16~mm, respectively showed average non-linearities of about 1.9\% for the 16~mm sensor which proved to be the best solution for this MIS structure. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2006.11.175}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547572518\&partnerID=40\&md5=539b18d870d02b6d3b8723768c640560}, author = {{\'A}guas, H., Pereira, S., Costa, D., Barquinha, P., Pereira, L., Fortunato, E., Martins, R.} } @article {Martins20021283, title = {32 Linear array position sensitive detector based on NIP and hetero a-Si:H microdevices}, journal = {Journal of Non-Crystalline Solids}, volume = {299-302}, number = {PART 2}, year = {2002}, note = {

cited By 10

}, pages = {1283-1288}, abstract = {

In this paper we present results concerning the performance exhibited by an integrated array of 32 one-dimensional amorphous silicon thin film position sensitive detectors based on nip and hetero amorphous silicon structures, with a total active area size below 1 cm2 linearity, its spatial resolution and response time, that make it one of the most interesting analog detector to be used in unmanned optical inspection control systems where a continuous detection process is required. This opens a wide range of applications for amorphous silicon devices in the area of image processing. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0022-3093(01)01149-8}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036531815\&partnerID=40\&md5=d37c5a51446d875d83154396a9c1e7b5}, author = {Martins, R.a b , Figueiredo, J.a b , Silva, V.a b , {\'A}guas, H.a b , Soares, F.a b , Marques, A.a b , Ferreira, I.a b , Fortunato,} } @article {Contreras20124583, title = {3D scanning characteristics of an amorphous silicon position sensitive detector array system}, journal = {Optics Express}, volume = {20}, number = {4}, year = {2012}, note = {

cited By 5

}, pages = {4583-4602}, abstract = {

The 3D scanning electro-optical characteristics of a data acquisition prototype system integrating a 32 linear array of 1D amorphous silicon position sensitive detectors (PSD) were analyzed. The system was mounted on a platform for imaging 3D objects using the triangulation principle with a sheet-of-light laser. New obtained results reveal a minimum possible gap or simulated defect detection of approximately 350 μm. Furthermore, a first study of the angle for 3D scanning was also performed, allowing for a broad range of angles to be used in the process. The relationship between the scanning angle of the incident light onto the object and the image displacement distance on the sensor was determined for the first time in this system setup. Rendering of 3D object profiles was performed at a significantly higher number of frames than in the past and was possible for an incident light angle range of 15 {\textdegree} to 85 {\textdegree}. {\textcopyright} 2012 Optical Society of America.

}, doi = {10.1364/OE.20.004583}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84857291188\&partnerID=40\&md5=532c9fb17661a1579b9b0bfc1a242d00}, author = {Contreras, J.a , Gomes, L.b , Filonovich, S.a , Correia, N.a , Fortunato, E.a , Martins, R.a , Ferreira, I.a} } @article {Bahubalindruni201530, title = {A-GIZO TFT neural modeling, circuit simulation and validation}, journal = {Solid-State Electronics}, volume = {105}, year = {2015}, note = {

cited By 1

}, pages = {30-36}, abstract = {

Development time and accuracy are measures that need to be taken into account when devising device models for a new technology. If complex circuits need to be designed immediately, then it is very important to reduce the time taken to realize the model. Solely based on data measurements, artificial neural networks (ANNs) modeling methodologies are capable of capturing small and large signal behavior of the transistor, with good accuracy, thus becoming excellent alternatives to more strenuous modeling approaches, such as physical and semi-empirical. This paper then addresses a static modeling methodology for amorphous Gallium-Indium-Zinc-Oxide - Thin Film Transistor (a-GIZO TFT), with different ANNs, namely: multilayer perceptron (MLP), radial basis functions (RBF) and least squares-support vector machine (LS-SVM). The modeling performance is validated by comparing the model outcome with measured data extracted from a real device. In case of a single transistor modeling and under the same training conditions, all the ANN approaches revealed a very good level of accuracy for large- and small-signal parameters (gm and gd), both in linear and saturation regions. However, in comparison to RBF and LS-SVM, the MLP achieves a very acceptable degree of accuracy with lesser complexity. The impact on simulation time is strongly related with model complexity, revealing that MLP is the most suitable approach for circuit simulations among the three ANNs. Accordingly, MLP is then extended for multiple TFTs with different aspect ratios and the network implemented in Verilog-A to be used with electric simulators. Further, a simple circuit (inverter) is simulated from the developed model and then the simulation outcome is validated with the fabricated circuit response. {\textcopyright} 2014 Elsevier Ltd . All rights reserved.

}, doi = {10.1016/j.sse.2014.11.009}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84920169995\&partnerID=40\&md5=d5e0ec76520067da9db9b174cefe8172}, author = {Bahubalindruni, P.G.a , Tavares, V.G.a , Barquinha, P.b , Duarte, C.a , Cardoso, N.a , De Oliveira, P.G.a , Martins, R.b , Fortu} } @article {Vieira1991479, title = {A-Si:H ambipolar diffusion length and effective lifetime measured by flying spot (FST) and spectral photovoltage (SPT) techniques}, journal = {Journal of Non-Crystalline Solids}, volume = {137-138}, number = {PART 1}, year = {1991}, note = {

cited By 4

}, pages = {479-482}, abstract = {

On this paper we report the physical model that supports the theory of the Flying Spot Technique (FST). Through this technique it is possible to determine separately the ambipolar diffusion length (L*) and the effective lifetime (τ*) of the generated carriers, using either Schottky diodes or quasi-ohmic sandwich structures. We also report a new static method based on the Spectral Photovoltage (SPT) that allows to infer the ambipolar diffusion length and to estimate the surface recombination velocity. {\textcopyright} 1991 Elsevier Science Publishers B.V. All rights reserved.

}, doi = {10.1016/S0022-3093(05)80159-0}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026415491\&partnerID=40\&md5=fff13bb5dcb3c9fb8af1aec6bb882d23}, author = {Vieira, M., Martins, R., Fortunato, E., Soares, F., Guimar{\~a}es, L.} } @article {Pereira20021289, title = {a-Si:H interface optimisation for thin film position sensitive detectors produced on polymeric substrates}, journal = {Journal of Non-Crystalline Solids}, volume = {299-302}, number = {PART 2}, year = {2002}, note = {

cited By 14

}, pages = {1289-1294}, abstract = {

In this paper we present results concerning the optimisation of the electronic and mechanical properties presented by amorphous silicon (a-Si:H) thin films produced on polyimide (Kapton{\textregistered} VN) substrates with different thicknesses (25, 50 and 75 μm) by the plasma enhanced chemical vapour deposition (PECVD) technique. The purpose of this study is to obtain a low defect density as well as low residual stresses (specially at the interface) in order to provide good performances for large area (10 mm wide by 80 mm long) flexible position sensitive detectors. The electrical and optical properties presented by the films will be correlated to the sensor characteristics. The properties of samples have been measured by dark/photoconductivity, constant photocurrent measurements (CPM) and the results have been compared with films deposited on Corning 7059 glass substrates during the same run deposition. The residual stresses were measured using an active optical triangulation and angle resolved scattering. The preliminary results indicate that the thinner polymeric substrate with 25 μm presents the highest density of states, which is associated to the residual stresses and strains associated within the film. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0022-3093(01)01150-4}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036530620\&partnerID=40\&md5=c8a0d3b449f231925488bb636d215f48}, author = {Pereira, L.a , Brida, D.a , Fortunato, E.a , Ferreira, I.a , {\'A}guas, H.a , Silva, V.a , Costa, M.F.M.b , Teixeira, V.b , Martins,} } @article {Neves20124381, title = {Aluminum doped zinc oxide sputtering targets obtained from nanostructured powders: Processing and application}, journal = {Journal of the European Ceramic Society}, volume = {32}, number = {16}, year = {2012}, note = {

cited By 27

}, pages = {4381-4391}, abstract = {

This work reports the production of ceramic targets based on nanostructured Al-doped ZnO (AZO) powders for sputtering applications. The nanostructured powder is obtained by a new patented process based on the detonation of an emulsion containing both Zn and Al metal precursors in the final proportion of 98:2wt\% (ZnO:Al 2O 3), through which the Al contains is highly uniform distributed over ZnO. Due to the nanostructured powder characteristics, the targets can be sintered at substantially lower temperatures (1150-1250{\textdegree}C) by conventional sintering, contributing to production costs reduction of ceramic targets and consequently the costs of photovoltaic and displays industries. Electrical resistivity values around 3.0-7.0{\texttimes}10 -3Ωcm have been obtained depending on final microstructure of the targets. The electro-optical properties of the films produced at room temperature with thicknesses around 360nm, besides being highly uniform exhibit a resistivity of about 1{\texttimes}10 -3Ωcm and a transmittance in the visible range above 90\%. {\textcopyright} 2012 Elsevier Ltd.

}, doi = {10.1016/j.jeurceramsoc.2012.08.007}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84866839575\&partnerID=40\&md5=83afb5f2dc54eeddeb0744800219c701}, author = {Neves, N.a b , Barros, R.a b , Antunes, E.a , Calado, J.a , Fortunato, E.b , Martins, R.b , Ferreira, I.b} } @article {Vieira19961193, title = {Amorphous and microcrystalline silicon p-i-n optical speed sensors based on the flying spot technique}, journal = {Journal of Non-Crystalline Solids}, volume = {198-200}, number = {PART 2}, year = {1996}, note = {

cited By 1

}, pages = {1193-1197}, abstract = {

From the flying spot technique (FST) the ambipolar diffusion length and the effective-lifetime of the carriers photogenerated by a moving light spot that strikes a p-i-n junction can be inferred. In this paper, those properties of a p-i-n junction are used together with an optical triangulation principle to determine the velocity of an object that is moving in the direction of a light source. The light reflected back from the object is analysed through an amorphous or a microcrystalline p-i-n structure. Its transient transverse photovoltage is dependent on the velocity of the object. A comparison between the performances of both kinds of devices is presented.

}, doi = {10.1016/0022-3093(96)00111-1}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030563421\&partnerID=40\&md5=1f3acdf883c8050ac9d702a04b1cc33f}, author = {Vieira, M.a , Fantoni, A.a , Koynov, S.a b , Cruz, J.a , Ma{\c c}arico, A.a , Martins, R.a} } @article {Teixeira200270, title = {Amorphous ITO thin films prepared by DC sputtering for electrochromic applications}, journal = {Thin Solid Films}, volume = {420-421}, year = {2002}, note = {

cited By 80

}, pages = {70-75}, abstract = {

Indium-Tin-Oxide (ITO) thin films were deposited on glass substrates using DC magnetron reactive sputtering at different bias voltages and substrate temperatures. Some improvements were obtained on film properties, microstructure and other physical characteristics for different conditions. Amorphous and polycrystalline films can be obtained for various deposition conditions. The transmission, absorption, spectral and diffuse reflection of ITO films were measured in some ranges of UV-Vis-NIR. The refractive index (n), Energy band gap Eg and the surface roughness of the film were derived from the measured spectra data. The carrier density (nc) and the carrier mobility (μ) of the film micro conductive properties were discussed. The films exhibited suitable optical transmittance and conductivity for electrochromic applications. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0040-6090(02)00656-9}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037011145\&partnerID=40\&md5=6baae2ec8905087cd877c5acea90afef}, author = {Teixeira, V.a , Cui, H.N.a d , Meng, L.J.b , Fortunato, E.c , Martins, R.e} } @article {Fortunato2007, title = {Amorphous IZO TTFTs with saturation mobilities exceeding 100 cm2/Vs}, journal = {Physica Status Solidi - Rapid Research Letters}, volume = {1}, number = {1}, year = {2007}, note = {

cited By 120

}, pages = {R34-R36}, abstract = {

In this paper we demonstrate the use of amorphous binary In2O3-ZnO oxides simultaneously as active channel layer and as source/drain regions in transparent thin film transistor (TTFT), processed at room temperature by rf sputtering. The TTFTs operate in the enhancement mode and their performances are thickness dependent. The best TTFTs exhibit saturation mobilities higher than 102 cm2/Vs, threshold voltages lower than 6 V, gate voltage swing of 0.8 V/dec and an on/off current ratio of 107. This mobility is at least two orders of magnitude higher than that of conventional amorphous silicon TFTs and comparable to or even better than other polycrystal-line semiconductors. {\textcopyright} 2007 Wiley-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/pssr.200600049}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-36048988960\&partnerID=40\&md5=39e4c32491e99312b15ed435167d378a}, author = {Fortunato, E., Barquinha, P., Pimentel, A., Pereira, L., Gon{\c c}alves, G., Martins, R.} } @article {Contreras2012812, title = {Amorphous silicon position sensitive detector array for fast 3-d object profiling}, journal = {IEEE Sensors Journal}, volume = {12}, number = {4}, year = {2012}, note = {

cited By 5

}, pages = {812-820}, abstract = {

A 32/128 linear array of 1-D amorphous silicon position sensitive detectors (PSD) was integrated into a self constructed suitable and portable data acquisition prototype system. The system is comprised by a commercially available existing electronics module suitable for photodiode data acquisition operations and by another adapter module, which allows for removal and replacement of the 32/128 PSD based sensor. This system is applied for imaging 3-D objects using the triangulation principle with a sheet-of-light laser. The sensor array response obtained from the reflected light of the object was fed into an electronic readout system and the corresponding signals were analyzed using the relevant data algorithm. The obtained results show a sensor nonlinearity of about 4\%-7\%, a wide sensor/system dynamic range and a 3-D profile spatial resolution supplied by each sensor strip of 339 μm, which can easily be reduced to 8.5 μm and even further with appropriate software modifications. {\textcopyright} 2011 IEEE.

}, doi = {10.1109/JSEN.2011.2164398}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84856854043\&partnerID=40\&md5=5d80aca83e95799c99b8c298ed843035}, author = {Contreras, J.a , Idzikowski, M.b , Pereira, S.a , Filonovich, S.A.a , Fortunato, E.a , Martins, R.a , Ferreira, I.a} } @article {Contreras20061792, title = {Amorphous silicon position sensitive detectors applied to micropositioning}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 11

}, pages = {1792-1796}, abstract = {

The position of a 40 μm wide by 400 μm long cantilever in a microscope was detected by a 32 lines array of 1D amorphous silicon position sensitive detectors (PSD). The sensor was placed in the ocular used for the CCD camera of a microscope and the alignment, focusing and positioning of the cantilever was achieved using the X-Y-Z translation table of the microscope that has a micrometer resolution controller. In this work we present results concerning the micro positioning of a cantilever and its holding structure through the reflected light that is detected by 1D/3D psd and converted to an analog signal proportional to the movement. The signal given by the 32 sensor array was analyzed directly without any electronic readout system or data algorithm. The obtained results show a linear behavior of the photovoltage relating X and Y movement, a non-linearity less than 2\% and spatial resolution of 600 μV/μm. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2006.02.026}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33744531493\&partnerID=40\&md5=23d73589aeaa546e21a214de7c13b936}, author = {Contreras, J.a b , Baptista, C.a , Ferreira, I.a , Costa, D.a , Pereira, S.a , {\'A}guas, H.a , Fortunato, E.a , Martins, R.a , Wier} } @article {Fortunato19981349, title = {Amorphous silicon sensors: From photo to chemical detection}, journal = {Journal of Non-Crystalline Solids}, volume = {227-230}, number = {PART 2}, year = {1998}, note = {

cited By 4

}, pages = {1349-1353}, abstract = {

This paper reports the performances of metal/insulator/semiconductor devices, simultaneously sensitive to hydrogen and to the visible region of the spectrum. The sensors used in this work are based on glass/Cr/a-SiH(n+)/a-Si:H(i)/SiOx/Pd structures, where the amorphous silicon was deposited by conventional r.f. techniques and the oxide grown thermally (in air) or chemically (in hydrogen peroxide). The proposed sensors present a response of \~{} 3 orders of magnitude change in the saturation current when in the presence of 400 ppm of hydrogen and an open circuit voltage that decreases in the presence of hydrogen, with a maximum spectral response at 500 nm. These sensors were also compared with equivalent crystalline silicon devices whose oxides were prepared exactly in the same conditions as the ones used for the a-Si:H devices. {\textcopyright} 1998 Elsevier Science B.V. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032065116\&partnerID=40\&md5=0b3fc55c4a150e6000c52419d1ddb1be}, author = {Fortunato, E.a , Malik, A.a , S{\^e}co, A.b , Ferreira, I.a , Martins, R.a} } @article {Fortunato199941, title = {Amorphous silicon thin films applied to photochemical sensors}, journal = {Vacuum}, volume = {52}, number = {1-2}, year = {1999}, note = {

cited By 2

}, pages = {41-44}, abstract = {

The present paper describes the properties of a photochemical sensor based on amorphous silicon MIS (Metal-Insulator-Semiconductor) diodes. The structure of the sensors used in this work are based on glass/Cr/a-SiH(n +)/a-Si:H(i)SiOx/Pd, where the amorphous silicon layers have been deposited by conventional plasma r.f. techniques. The proposed photochemical sensors present a 2-3 orders of magnitude change in the saturation current and a decrease of up to 40\% on the open circuit voltage when in the presence of 400 ppm of hydrogen. The overall performance of these sensors, associated with the low cost fabrication technology, suggests that, in the near future, it will be possible to use them in several industrial applications. {\textcopyright} 1998 Elsevier Science Ltd. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032762163\&partnerID=40\&md5=8717278e64d5830ec47b7a9f7983c161}, author = {Fortunato, E., Malik, A., Martins, R.} } @article {Zhang2005268, title = {Amorphous silicon-based PINIP structure for color sensor}, journal = {Thin Solid Films}, volume = {487}, number = {1-2}, year = {2005}, note = {

cited By 5

}, pages = {268-270}, abstract = {

A series of hydrogenated amorphous silicon carbide (a-SiC:H) films was prepared by plasma enhanced chemical vapor deposition (PECVD) technology. The microstructure and photoelectronic properties of the film are investigated by absorption spectra (in the ultraviolet to near-infrared range) and Fourier transform infrared (FTIR) spectra. The results show that good band gap controllability (1.83-3.64 eV) was achieved by adjusting the plasma parameters. In the energy range around 2.1 eV, the a-Si1-xCx:H films exhibit good photosensitivity, opening the possibility to use this wide band gap material for device application, especially when blue color detectors are concerned. A multilayer device with a stack of glass/TCO(ZnO:Ga)/P(a-SiC:H)/I(a- SiC:H)/N(a-Si:H)/I(a-Si:H)/P(a-Si:H)/Al has been prepared. The devices can detect blue and red colors under different bias voltages. The optimization of the device, especially the film thickness and the band gap offset used to achieve better detectivity, is also done in this work. {\textcopyright} 2005 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2005.01.077}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-22944462068\&partnerID=40\&md5=c076da3ee27928183d5d224af58c7db5}, author = {Zhang, S., Raniero, L., Fortunato, E., Ferreira, I., {\'A}guas, H., Martins, R.} } @article {Martins2007, title = {Amorphous/nanocrystalline silicon biosensor for the specific identification of unamplified nucleic acid sequences using gold nanoparticle probes}, journal = {Applied Physics Letters}, volume = {90}, number = {2}, year = {2007}, note = {

cited By 34

}, abstract = {

Amorphous/nanocrystalline silicon p i' i i' n devices fabricated on micromachined glass substrates are integrated with oligonucleotide-derivatized gold nanoparticles for a colorimetric detection method. The method enables the specific detection and quantification of unamplified nucleic acid sequences (DNA and RNA) without the need to functionalize the glass surface, allowing for resolution of single nucleotide differences between DNA and RNA sequences-single nucleotide polymorphism and mutation detection. The detector{\textquoteright}s substrate is glass and the sample is directly applied on the back side of the biosensor, ensuring a direct optical coupling of the assays with a concomitant maximum photon capture and the possibility to reuse the sensor. {\textcopyright} 2007 American Institute of Physics.

}, doi = {10.1063/1.2431449}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33846205122\&partnerID=40\&md5=fcfb8594ac2767ebd479cb88976a5c35}, author = {Martins, R.a , Baptista, P.b , Raniero, L.a c , Doria, G.b , Silva, L.a , Franco, R.d , Fortunato, E.a} } @article {Bahubalindruni2015547, title = {Analog circuits with high-gain topologies using a-GIZO TFTs on glass}, journal = {IEEE/OSA Journal of Display Technology}, volume = {11}, number = {6}, year = {2015}, note = {

cited By 3

}, pages = {547-553}, abstract = {

This paper presents analog building blocks that find potential applications in display panels. A buffer (source-follower), subtractor, adder, and high-gain amplifier, employing only n-type enhancement amorphous gallium-indium-zinc-oxide thin-film transistors (a-GIZO TFTs), were designed, simulated, fabricated, and characterized. Circuit simulations were carried out using a neural model developed in-house from the measured characteristics of the transistors. The adder-subtractor circuit presents a power consumption of 0.26 mW, and the amplifier presents a gain of 34 dB and a power consumption of 0.576 mW, with a load of 10 MΩ16 pF. To the authors{\textquoteright} knowledge, this is the highest gain reported so far for a single-stage amplifier with a-GIZO TFT technology. {\textcopyright} 2015 IEEE.

}, doi = {10.1109/JDT.2014.2378058}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84929315401\&partnerID=40\&md5=7642a5fe8721890faf514bcf85953ca4}, author = {Bahubalindruni, P.G.a , Silva, B.a , Tavares, V.G.a , Barquinha, P.b , Cardoso, N.a , Guedes De Oliveira, P.a , Martins, R.b , F} } @article {Topi{\v c}19971377, title = {Analysis of front contact heterojunction in a-Si:H one-dimensional position sensitive detectors}, journal = {Review of Scientific Instruments}, volume = {68}, number = {3}, year = {1997}, note = {

cited By 1

}, pages = {1377-1381}, abstract = {

The influence of different transparent conducting oxides (TCO) on the transverse photoelectrical properties of one-dimensional position sensitive detectors based on p-i-n amorphous silicon structures was studied. For both SnO 2 and indium tin oxide, poor quality of the p layer was revealed by secondary ion mass spectroscopy measurements. Good agreement between experimental and simulation characteristics of TCO/p-i-n structure was additionally conditioned by a strong increase in defect states at the p layer surface which can be attributed to the reduction/ oxidation process at the TCO/p interface. However, the analysis showed that under reverse bias the spectral response of the p-i-n structure is not significantly affected by different TCO layers and conditions at the TCO/p heterojunction. Nevertheless, indium tin oxide is less appropriate for a front TCO layer due to the poor reverse dark current-voltage characteristic, i.e., higher leakage current component leading to lower signal to noise ratio. {\textcopyright} 1997 American Institute of Physics.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-4043100666\&partnerID=40\&md5=58c871dfe426c00db5785847a7176df1}, author = {Topi{\v c}, M.a , Smole, F.a , Furlan, J.a , Fortunato, E.b , Martins, R.b} } @article {Fortunato19941151, title = {Application of thin film technology to optical sensors}, journal = {Vacuum}, volume = {45}, number = {10-11}, year = {1994}, note = {

cited By 0

}, pages = {1151-1154}, abstract = {

In this paper we present results of PIN single and dual axis Thin Film Position Sensitive Detectors (TFPSD) based on hydrogenated amorphous silicon (a-Si:H) technology, with a wide detection area (up to 80 {\texttimes} 80 mm). These sensors provide an alternative to Charge Coupled Devices (CCDs) when large inspection areas are needed, under a requirement to use simpler technology. In this paper we analyse the forward and reverse I-V characteristics in the dark and under illumination, as well as the device linearity of TFPSD. {\textcopyright} 1994.

}, doi = {10.1016/0042-207X(94)90050-7}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028518220\&partnerID=40\&md5=9962cd611b69d4d800d325f7655bc641}, author = {Fortunato, E.a , Lavareda, G.a , Vieira, M.a , Martins, R.a , Ferreira, L.b} } @article {Mei2004168, title = {Aqueous tape casting of low-k cordierite substrate: The influence of glass content}, journal = {Materials Science Forum}, volume = {455-456}, year = {2004}, note = {

cited By 1

}, pages = {168-171}, abstract = {

Thick films of cordierite-based glass ceramics were prepared by aqueous tape casting from suspensions containing 80-wt\% solids. The weight proportions of cordierite/glass ranged from 70/30 to 30/70 in order to investigate the effect of glass content on the rheological behaviour and on the microstructures and properties of the green tapes. Suspensions with 50 to 60-wt\% glass content exhibited the lowest viscosity values among all the slurries investigated, while the green tape containing 30-wt\% glass presented homogenous microstructures at both top and bottom surfaces, contrarily to the observations for the other compositions. The green densities increased with glass content. The sintered tapes (1150{\textdegree}C, 2h) containing 50 to 60-wt\% glass exhibited the lowest values for the dielectric constant (\~{}5.2) and dielectric loss (\~{}0.002) at 1MHz.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17144449996\&partnerID=40\&md5=c17b5665288e9c4381f2783a1c3e6e4d}, author = {Mei, S.a , Yang, J.a , Ferreira, J.M.F.a , Martins, R.b} } @article {Raniero2004104, title = {Batch processing method to deposit a-Si:H films by PECVD}, journal = {Materials Science Forum}, volume = {455-456}, year = {2004}, note = {

cited By 1

}, pages = {104-107}, abstract = {

This work reports a technique to obtain electronic grade intrinsic amorphous silicon using the plasma enhanced chemical vapour deposition technique at 13.56 MHz. The batch processing method consists of igniting the plasma process through a neutral gas such as hydrogen or helium and only feeding the carrier gas containing the species to be decomposed into the reactor when the plasma is stabilized. By doing so, no surface damage is induced in the first deposited layers and so a more compacted and stable film is produced, compared to amorphous films grown by conventional methods. The best deposition conditions to produce films with good transport properties for optoelectronic applications are: temperature ≈ 473 K, 60 \< pressure 87 Pa, power density of 32 mW/cm2 and flow of silane ≈ 10 sccm. The growth rate and the microstructure factor are 1.5 {\r A}/s and 3.3{\texttimes}10-2, respectively, while the activation energy ≈ 0.8 eV; dark conductivity at room temperature ≈ 4.37{\texttimes}10-10 (ωcm)-1; photosensiti-vity ≈ 5.02{\texttimes}l06; density of states ≈ 6.6{\texttimes}1015 cm-3; bonded hydrogen concentration ≈ 20 at\% and optical band gap ≈ 1.75 eV.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-3142754892\&partnerID=40\&md5=c14cf60ae70174c3094afbd7503a5a81}, author = {Raniero, L., {\'A}guas, H., Pereira, L., Fortunato, E., Ferreira, I., Martins, R.} } @article {Bernacka-Wojcik201387, title = {Bio-microfluidic platform for gold nanoprobe based DNA detection-application to Mycobacterium tuberculosis}, journal = {Biosensors and Bioelectronics}, volume = {48}, year = {2013}, note = {

cited By 15

}, pages = {87-93}, abstract = {

We have projected and fabricated a microfluidic platform for DNA sensing that makes use of an optical colorimetric detection method based on gold nanoparticles. The platform was fabricated using replica moulding technology in PDMS patterned by high-aspect-ratio SU-8 moulds. Biochips of various geometries were tested and evaluated in order to find out the most efficient architecture, and the rational for design, microfabrication and detection performance is presented. The best biochip configuration has been successfully applied to the DNA detection of Mycobacterium tuberculosis using only 3. l on DNA solution (i.e. 90. ng of target DNA), therefore a 20-fold reduction of reagents volume is obtained when compared with the actual state of the art. {\textcopyright} 2013 Elsevier B.V.

}, doi = {10.1016/j.bios.2013.03.079}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84877336998\&partnerID=40\&md5=41c31b1f1b60b47ba235516933e10cad}, author = {Bernacka-Wojcik, I.a , Lopes, P.b , Catarina Vaz, A.a , Veigas, B.a c , Jerzy Wojcik, P.a , Simoes, P.b , Barata, D.a , Fortunat} } @article {Mendes2015, title = {Broadband light trapping in thin film solar cells with self-organized plasmonic nanocolloids}, journal = {Nanotechnology}, volume = {26}, number = {13}, year = {2015}, note = {

cited By 15

}, abstract = {

The intense light scattered from metal nanoparticles sustaining surface plasmons makes them attractive for light trapping in photovoltaic applications. However, a strong resonant response from nanoparticle ensembles can only be obtained if the particles have monodisperse physical properties. Presently, the chemical synthesis of colloidal nanoparticles is the method that produces the highest monodispersion in geometry and material quality, with the added benefits of being low-temperature, low-cost, easily scalable and of allowing control of the surface coverage of the deposited particles. In this paper, novel plasmonic back-reflector structures were developed using spherical gold colloids with appropriate dimensions for pronounced far-field scattering. The plasmonic back reflectors are incorporated in the rear contact of thin film n-i-p nanocrystalline silicon solar cells to boost their photocurrent generation via optical path length enhancement inside the silicon layer. The quantum efficiency spectra of the devices revealed a remarkable broadband enhancement, resulting from both light scattering from the metal nanoparticles and improved light incoupling caused by the hemispherical corrugations at the cells{\textquoteright} front surface formed from the deposition of material over the spherically shaped colloids. {\textcopyright} 2015 IOP Publishing Ltd.

}, doi = {10.1088/0957-4484/26/13/135202}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84925256267\&partnerID=40\&md5=a9417c7f6caaf92855aa2b51bc88caf3}, author = {Mendes, M.J.a b , Morawiec, S.b c , Mateus, T.a , Lyubchyk, A.a , {\'A}guas, H.a , Ferreira, I.a , Fortunato, E.a , Martins, R.a , P} } @article {Nolan201110, title = {The characterisation of aerosol assisted CVD conducting, photocatalytic indium doped zinc oxide films}, journal = {Journal of Photochemistry and Photobiology A: Chemistry}, volume = {219}, number = {1}, year = {2011}, note = {

cited By 21

}, pages = {10-15}, abstract = {

Indium doped, and undoped, zinc oxide films were deposited using aerosol assisted chemical vapour deposition (AACVD) at atmospheric pressure on glass substrates. Electrical measurements (I-V) showed a reduction in resistivity following the addition of indium, and XRD analysis revealed an associated switch to c-axis preferred crystal orientation. The ability of the films to oxidise organic material on their surface was analysed using stearic acid as the model contaminant under ultra-violet (UV, 365 nm) irradiation. The In-doped films displayed a greater rate of organic decomposition, which we attribute to the formation of a platelet surface structure having a larger surface area than the undoped films, on which the UV generated electrons and holes may react to form active photocatalytic species. In addition we suggest that the switch to c-axis crystal orientation may reduce the electron-hole pair recombination rate at the grain boundaries, due to an improvement in crystallinity and related reduction in carrier scattering losses, leading to an increase in photocatalytic organic decomposition rate. {\textcopyright} 2011 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jphotochem.2011.01.010}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79952991194\&partnerID=40\&md5=b9df2a57de0ae5f95953a545636c5d05}, author = {Nolan, M.G.a , Hamilton, J.A.a , Obrien, S.a , Bruno, G.c , Pereira, L.d , Fortunato, E.d , Martins, R.d , Povey, I.M.a , Pemble} } @article {Fortunato1999222, title = {Characteristics of a linear array of a-Si:H thin film position sensitive detector}, journal = {Thin Solid Films}, volume = {337}, number = {1-2}, year = {1999}, note = {

cited By 7

}, pages = {222-225}, abstract = {

The increasing demand in automation processes in finishing techniques also calls for automatic measurement and inspection methods. These methods ought to be installed as close as possible to the production process and they ought to measure the values needed in a safe and fast way, without disturbing the process itself. Simultaneously they should be free of wear and insensitive against mechanical perturbations. This approach can be reached by proper combination of the laser triangulation technique with an array of linear position sensitive detectors, able to supply information about the surface finishing of an object. This is the aim of this paper that envisages to present experimental results of the performances exhibited by such an array constituting 128 elements. The analogue information supplied by this array is processed by an analogue/digital converter, directly coupled to the array and whose information is computer processed, concerning the recognition of patterns and the processing of information collected over the object to be inspected. {\textcopyright} 1999 Elsevier Science S.A. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0006307253\&partnerID=40\&md5=a531e6767b6c6992d91e6242f2514978}, author = {Fortunato, E., Soares, F., Teodoro, P., Guimar{\~a}es, N., Mendes, M., {\'A}guas, H., Silva, V., Martins, R.} } @article {Fortunato2002233, title = {Characterization of aluminium doped zinc oxide thin films deposited on polymeric substrates}, journal = {Vacuum}, volume = {64}, number = {3-4}, year = {2002}, note = {

cited By 43

}, pages = {233-236}, abstract = {

We report, for the first time, results on transparent ZnO:Al thin films deposited on polyester (Mylar type D, 100 μm thickness) substrates at room temperature by magnetron sputtering. The structural, optical and electrical properties of the deposited films have been studied. The samples are polycrystalline with a hexagonal wurtzite structure and a strong crystallographic c-axis orientation (0 0 2) perpendicular to the substrate surface. The ZnO:Al thin films with 83\% transmittance in the visible region and a resistivity as low as 3.6 {\texttimes} 10-2 Ωcm have been obtained, as deposited. The obtained results are comparable to those obtained on glass substrates, opening a new field of low cost, light weight, small volume, flexible and unbreakable large area optoelectronic devices. {\textcopyright} 2002 Elsevier Science Ltd. All rights reserved.

}, doi = {10.1016/S0042-207X(01)00319-0}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036135003\&partnerID=40\&md5=9fd9e3e19ab1d0b82f67e0a21d48bca2}, author = {Fortunato, E., Nunes, P., Costa, D., Brida, D., Ferreira, I., Martins, R.} } @article {Zhang20061410, title = {Characterization of nanocrystalline silicon carbide films}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 6

}, pages = {1410-1415}, abstract = {

Amorphous silicon carbide films were obtained by plasma enhanced chemical vapor deposition (PECVD) technique using a gas mixture of silane, methane, and hydrogen with a high excitation frequency and a high hydrogen dilution ratio. The high temperature annealing behavior of the amorphous silicon carbide films was studied by annealing at 1373 K for 1 h in nitrogen atmosphere. A very thin Au film was deposited on part of the films to investigate the metal induced crystallization effect. Well aligned nanotubes were found on the silicon carbide films covered by a thin gold layer after the high temperature annealing by atomic force microscopy. Further study is necessary to identify the nature of the nanotubes and elucidate their growth mechanism. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2006.02.027}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33745463684\&partnerID=40\&md5=e1f0a811abe20030388883e6261bf111}, author = {Zhang, S., Pereira, L., Hu, Z., Ranieiro, L., Fortonato, E., Ferreira, I., Martins, R.} } @article {Silva2008508, title = {Characterization of optoelectronic platform using an amorphous/nanocrystalline silicon biosensor for the specific identification of nucleic acid sequences based on gold nanoparticle probes}, journal = {Sensors and Actuators, B: Chemical}, volume = {132}, number = {2}, year = {2008}, note = {

cited By 9

}, pages = {508-511}, abstract = {

Nanotechnology is having a positive impact on nearly every industry, and in particular in healthcare, where it is extending the limits of molecular diagnostics to the nanoscale-nanodiagnostics. Here we describe an innovative optoelectronic platform for the colorimetric detection of nucleic acids based on oligonucleotide-derivatized gold nanoparticles. The device integrates an amorphous/nanocrystalline biosensor and a light emission source with a gold nanoprobe for specific DNA detection. This low cost, fast and simple optoelectronic platform permits detection of few picomole of nucleic acid without target or signal amplification making it suitable for application in population diagnostics and in point-of-care hand-held devices. {\textcopyright} 2007 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.snb.2007.11.015}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-44849131659\&partnerID=40\&md5=1ffc5b6437ce754d8cc950f898ae7a5a}, author = {Silva, L.B.a , Baptista, P.b , Raniero, L.c , Doria, G.b , Martins, R.a , Fortunato, E.a} } @article {Zhang200477, title = {Characterization of polymorphous silicon thin film and solar cells}, journal = {Materials Science Forum}, volume = {455-456}, year = {2004}, note = {

cited By 0

}, pages = {77-80}, abstract = {

Polymorphous silicon (pm-Si:H) films have been prepared by a new regime of plasma enhanced chemical vapour deposition in the region adjacent of phase transition from amorphous to microcrystalline state. Comparing to the conventional amorphous silicon (a-Si:H), the pm-Si:H has higher photoconductivity (σph), better stability, and a broader light spectral response range in the longer wavelength range. It can be found from Raman spectra that there is a notable improvement in the medium range order. There are a blue shift for the stretching mode of IR. spectra and a red shift for the wagging mode. The shifts are attributed to the variation of the microstructure. By using pm-Si:H film as intrinsic layer, a p-i-n junction solar cell was prepared with the initial efficiency of 8.51\% and a stabilized efficiency of 8.01\% (AM1.5, 100mw/cm2) at room temperature (T R).

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17144452330\&partnerID=40\&md5=15ada88034195da0899f595c105cc6ae}, author = {Zhang, S.a b , Xu, Y.a , Liao, X.a , Martins, R.b , Fortunate, E.b , Zeng, X.a , Hu, Z.a , Kong, G.a} } @article {Zhang2005343, title = {Characterization of silicon carbide thin films and their use in colour sensor}, journal = {Solar Energy Materials and Solar Cells}, volume = {87}, number = {1-4}, year = {2005}, note = {

cited By 5

}, pages = {343-348}, abstract = {

A series of hydrogenated amorphous silicon carbide (a-Si 1- xC x:H) films were prepared by plasma-enhanced chemical vapour deposition (PECVD) using a gas mixture of silane, methane, and hydrogen as the reactive source. The previous results show that a high excitation frequency, together with a high hydrogen dilution ratio of the reactive gases, allow an easier incorporation of the carbon atoms into the silicon-rich a-Si 1-xC x:H film, widen the valence controllability. The data show that films with optical gaps ranging from about 1.9 to 3.6 eV could be produced. In this work the influence of the hydrogen dilution ratio of the reactive gases on the a-Si 1-xC x:H film properties was investigated. The microstuctural and photoelectronic properties of the silicon carbide films were characterized by Rutherford backscattering spectrometry (RBS), elastic recoil detection analysis (ERDA), and FT-IR spectrometry. The results show that a higher hydrogen dilution ratio enhances the incorporation of silicon atoms in the amorphous carbon matrix for carbon-rich a-Si 1-xC x:H films. One pin structure was prepared by using the a-Si 1-xC x:H film as the intrinsic layer. The light spectral response shows that this structure fits the requirement for the top junction of colour sensor. {\textcopyright} 2004 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.solmat.2004.06.019}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-20244375412\&partnerID=40\&md5=626ad1c5e1f4448c37893e87b48520ad}, author = {Zhang, S.a b , Raniero, L.a , Fortunato, E.a , Liao, X.b , Hu, Z.b , Ferreira, I.a , {\'A}guas, H.a , Ramos, A.R.c d , Alves, E.c d} } @article {Zhang2004530, title = {Characterization of silicon carbide thin films prepared by VHF-PECVD technology}, journal = {Journal of Non-Crystalline Solids}, volume = {338-340}, number = {1 SPEC. ISS.}, year = {2004}, note = {

cited By 19

}, pages = {530-533}, abstract = {

A series of hydrogenated amorphous silicon carbide films were prepared by plasma enhanced chemical vapor deposition (PECVD) using a gas mixture of silane, methane, and hydrogen as the reactive source and an excitation frequency of 27.12 MHz. Compared to the typical radio frequency deposition technique, the very high plasma excitation frequency increases the density of the electrons and decreases the electron temperature, which helps the dissociation of the SiH4 and CH4, and reduces the energetic ion impact on the growth surface of the thin film. Thus, dense-films with lower bulk density of states and higher growth rate are expected, as confirmed by spectroscopic ellipsometry data. Apart from that, a substantial reduction of bulk defects is achieved, allowing an improvement of the valence controllability (widening of the optical gap from about 1.9 to 3.6 eV). In this work results concerning the microstuctural and photoelectronic properties of the silicon carbide films will be discussed in detail, correlating them with the deposition process conditions used as well as with the gas phase composition of the mixtures used. {\textcopyright} 2004 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2004.03.035}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-2942528965\&partnerID=40\&md5=87b3fd782c613a31705d11432eb368ea}, author = {Zhang, S., Raniero, L., Fortunato, E., Pereira, L., Martins, N., Canhola, P., Ferreira, I., Nedev, N., {\'A}guas, H., Martins, R.} } @article {Raniero2004206, title = {Characterization of the density of states of polymorphous silicon films produced at 13.56 and 27.12 MHz using CPM and SCLC techniques}, journal = {Journal of Non-Crystalline Solids}, volume = {338-340}, number = {1 SPEC. ISS.}, year = {2004}, note = {

cited By 9

}, pages = {206-210}, abstract = {

The aim of this paper is to compare the density of bulk states (DOS) of polymorphous silicon (pm-Si:H) films produced by plasma enhanced chemical vapor deposition at 13.56 and 27.12 MHz using the constant photocurrent method and the space charge limited current (SCLC) technique. The data achieved revealed that the set of films produced present similar DOS. Apart from that, data concerning the correlation of the deposition conditions that lead to the production of pm-Si:H as well as their characteristics, such as the hydrogen content and how hydrogen is bonded, will be discussed, giving special emphasis to the set of mechanical stresses developed. By doing so we could get a better understanding of the nature of hydrogen bonding in pm-Si:H films as well as to determine the role of the excitation frequency on the film{\textquoteright}s performances, where films with amounts of hydrogen around 20 at.\% can have DOS as low as 8 {\texttimes} 10 14 cm-3 with Urbach energies in the range of 41-50 meV. {\textcopyright} 2004 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2004.02.054}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-2942558760\&partnerID=40\&md5=3707da2d039761b028de8316201a33cf}, author = {Raniero, L., Pereira, L., Zhang, S., Ferreira, I., {\'A}guas, H., Fortunato, E., Martins, R.} } @article {Nunes201645, title = {Charging effects and surface potential variations of Cu-based nanowires}, journal = {Thin Solid Films}, volume = {601}, year = {2016}, note = {

cited By 0

}, pages = {45-53}, abstract = {

The present work reports charging effects and surface potential variations in pure copper, cuprous oxide and cupric oxide nanowires observed by electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM). The copper nanowires were produced by wet synthesis, oxidation into cuprous oxide nanowires was achieved through microwave irradiation and cupric oxide nanowires were obtained via furnace annealing in atmospheric conditions. Structural characterization of the nanowires was carried out by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. During the EFM experiments the electrostatic field of the positive probe charged negatively the Cu-based nanowires, which in turn polarized the SiO2 dielectric substrate. Both the probe/nanowire capacitance as well as the substrate polarization increased with the applied bias. Cu2O and CuO nanowires behaved distinctively during the EFM measurements in accordance with their band gap energies. The work functions (WF) of the Cu-based nanowires, obtained by KPFM measurements, yielded WFCuO \> WFCu \> WFCu2O. {\textcopyright} 2015 Elsevier B.V.

}, doi = {10.1016/j.tsf.2015.11.077}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959511315\&partnerID=40\&md5=84484a1804f82e2d9a6178db19cf309c}, author = {Nunes, D.a , Calmeiro, T.R.a , Nandy, S.a , Pinto, J.V.a , Pimentel, A.a , Barquinha, P.a , Carvalho, P.A.b c , Walmsley, J.C.d} } @article {Wang2008, title = {Co-doping of aluminium and gallium with nitrogen in ZnO films deposited by RF magnetron sputtering}, journal = {Journal of Physics Condensed Matter}, volume = {20}, number = {7}, year = {2008}, note = {

cited By 5

}, abstract = {

N, (N+Ga) and (N+Al) doped ZnO films were deposited on c-plane sapphire substrates by RF magnetron sputtering at room temperature. The samples were characterized by their structural, surface morphological, compositional and optical properties. The x-ray diffraction studies confirmed the co-doping of (N+Ga) and (N+Al) besides showing improvement in the crystallinity when compared with the single Ndoping. The surface of the films becomes rougher after co-doping. The x-ray photoelectron spectroscopy and Rutherford back-scattering analysis indicate that the co-doping changes the chemical states and varies the amount of nitrogen (N) in ZnO. The amount of {\textquoteright}N{\textquoteright} has been greatly increased for (N+Ga) co-doping, indicating that it is the best co-doping pair for p-type ZnO. Additionally, co-doping has increased the average visible transmittance (40-650nm) and the optical band gap is shifted towards shorter wavelength. In the case of (N+Al) co-doping, the band gap becomes wider than that of undoped ZnO. {\textcopyright} IOP Publishing Ltd.

}, doi = {10.1088/0953-8984/20/7/075220}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-38949196677\&partnerID=40\&md5=4ee5eea66663205cb9bde0f54e8f3c85}, author = {Wang, J.a , Elamurugu, E.a , Barradas, N.P.b , Alves, E.b , Rego, A.c , Gon{\c c}alves, G.a , Martins, R.a , Fortunato, E.a} } @article {Contreras201426, title = {Color sensing ability of an amorphous silicon position sensitive detector array system}, journal = {Sensors and Actuators, A: Physical}, volume = {205}, year = {2014}, note = {

cited By 1

}, pages = {26-37}, abstract = {

The color sensing ability of a data acquisition prototype system integrating a 32 linear array of 1D amorphous silicon position sensitive detectors (PSD) was analyzed. Besides being used to reproduce a 3D profile of highly reflective surfaces, here we show that it can also differentiate primary red, green, blue (RGB) and derived colors. This was realized by using an incident beam with a RGB color combination and adequate integration times taking into account that a color surface mostly reflects its corresponding color. A mean colorimetric error of 25.7 was obtained. Overall, we show that color detection is possible via the use of this sensor array system, composed by a simpler amorphous silicon pin junction. {\textcopyright} 2013 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.sna.2013.10.017}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84887841015\&partnerID=40\&md5=2f0303e0272324f7c86ea40a59c8c711}, author = {Contreras, J.a b , Martins, R.a b , Wojcik, P.a b , Filonovich, S.a b , Aguas, H.a b , Gomes, L.c d , Fortunato, E.a b , Ferreir} } @article {Ferreira2003231, title = {Combining HW-CVD and PECVD techniques to produce a-Si:H films}, journal = {Thin Solid Films}, volume = {427}, number = {1-2}, year = {2003}, note = {

cited By 3

}, pages = {231-235}, abstract = {

Amorphous undoped a-Si:H films have been produced by hot wire plasma assisted chemical vapour deposition (HWPA-CVD), which combines the hot wire chemical vapour deposition (HW-CVD) and plasma enhanced chemical vapour deposition techniques. In this work we analyse the dissociation mechanism of the gas during the film growth in both processes with a quadrupole mass spectrometer. Besides that, the energy delivered to the gas dissociation is determined and correlated with the films properties. Thus, based on the results of the dissociated species for each deposition condition and process, we explain why the growth rate is enhanced when the filament temperature rises in HW-CVD process and why it decreases as r.f. power is enhanced in HWPA-CVD process. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0040-6090(02)01187-2}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037416653\&partnerID=40\&md5=6d32e8a06ae22d47cf86c0f764cc47d0}, author = {Ferreira, I., Fortunato, E., Martins, R.} } @article {Moldovan201681, title = {A compact model and direct parameters extraction techniques For amorphous gallium-indium-zinc-oxide thin film transistors}, journal = {Solid-State Electronics}, volume = {126}, year = {2016}, note = {

cited By 0

}, pages = {81-86}, abstract = {

An advanced compact and analytical drain current model for the amorphous gallium indium zinc oxide (GIZO) thin film transistors (TFTs) is proposed. Its output saturation behavior is improved by introducing a new asymptotic function. All model parameters were extracted using an adapted version of the Universal Method and Extraction Procedure (UMEM) applied for the first time for GIZO devices in a simple and direct form. We demonstrate the correct behavior of the model for negative VDS, a necessity for a complete compact model. In this way we prove the symmetry of source and drain electrodes and extend the range of applications to both signs of VDS. The model, in Verilog-A code, is implemented in Electronic Design Automation (EDA) tools, such as Smart Spice, and compared with measurements of TFTs. It describes accurately the experimental~characteristics in the whole range of GIZO TFTs operation,~making the~model~suitable for the design of circuits using these types of devices. {\textcopyright} 2016 Elsevier Ltd

}, doi = {10.1016/j.sse.2016.09.011}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994316272\&partnerID=40\&md5=2fabff4e66ae1543884be257d43d89a2}, author = {Moldovan, O.a , Castro-Carranza, A.b , Cerdeira, A.c , Estrada, M.c , Barquinha, P.d , Martins, R.d , Fortunato, E.d , Miljakovi} } @article {Lajn2013, title = {Comparative study of transparent rectifying contacts on semiconducting oxide single crystals and amorphous thin films}, journal = {Journal of Applied Physics}, volume = {113}, number = {4}, year = {2013}, note = {

cited By 7

}, abstract = {

We demonstrate fully transparent, highly rectifying contacts (TRC) on amorphous GaInZnO and compare them to TRC fabricated on single crystalline bulk ZnO and heteroepitaxial ZnO thin films. The contacts{\textquoteright} transparency in the visible spectral range exceeds 70\%. From numerical simulations, we conclude that thermionic emission is the dominating transport mechanism, however, for several samples with low net doping density diffusion theory must be applied. The detailed investigation of the rectification properties of the TRC using temperature-dependent current-voltage and capacitance-voltage measurements reveals that barrier inhomogeneities govern the IV-characteristics of all diodes irrespective of the sample crystallinity. Assuming a Gaussian barrier height distribution, the extracted mean barrier heights typically range between 1.1 and 1.3 V. The width of the barrier distribution correlates with the mean barrier height and ranges from 110 to 130 mV. By compiling literature data, we found that this correlation holds also true for Schottky diodes on elemental and III-V semiconductors. {\textcopyright} 2013 American Institute of Physics.

}, doi = {10.1063/1.4789000}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84873660230\&partnerID=40\&md5=a3743ea65f5d7cc06accbf4f71e1f70f}, author = {Lajn, A.a , Von Wenckstern, H.a , Grundmann, M.a , Wagner, G.b , Barquinha, P.c , Fortunato, E.c , Martins, R.c} } @article {Martins20114491, title = {Complementary metal oxide semiconductor technology with and on paper}, journal = {Advanced Materials}, volume = {23}, number = {39}, year = {2011}, note = {

cited By 88

}, pages = {4491-4496}, abstract = {

A complementary metal oxide semiconductor (CMOS) device is described. The device is based on n-(In-Ga-Zn-O) and p-type (SnO x) active oxide semiconductors and uses a transparent conductive oxide (In-Zn-O) as gate electrode that sits on a flexible, recyclable paper substrate that is simultaneously the substrate and the dielectric. Copyright {\textcopyright} 2011 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/adma.201102232}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-80054705024\&partnerID=40\&md5=5b2248dc71c281b7ecff03b39f6209fb}, author = {Martins, R.a , Nathan, A.b , Barros, R.a , Pereira, L.a , Barquinha, P.a , Correia, N.a , Costa, R.a , Ahnood, A.b , Ferreira, I} } @article {Almeida2002111, title = {Composite systems for flexible display applications from cellulose derivatives}, journal = {Synthetic Metals}, volume = {127}, number = {1-3}, year = {2002}, note = {

cited By 7

}, pages = {111-114}, abstract = {

In this work, we study the electro-optical behaviour of cellulose/liquid crystal-based composite systems, in particular the influence of the flexible substrates and its conductive layers in the electro-optical behaviour of these kind of cells. Four cells were made using, respectively, two different substrates (a flexible polymer (poly(ethylene terephthalate) (PET)) and a soda lime glass) and two different conductive layers (indium tin oxide (ITO) and aluminium zinc oxide (AZO)). The conductive layer (AZO) was deposited in both, flexible and rigid substrates, for the same conditions, and the same substrates coated with ITO are commercially available. The cells were prepared from solid films of hydroxypropylcellulose (HPC) (30 μm thick) cross linked with 1,4-diisocyanatobutane (BDI) (7\% w/w) and the nematic liquid crystal E7 (Merck, UK). The four different substrates were electrically and morphologically characterised. We have analysed all samples by light transmission and determined the maximum transmission, contrast and Von. We show a comparison of the results obtained for both flexible and rigid cells and discuss them in terms of the proposed working mechanism for these systems. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0379-6779(01)00613-0}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037177192\&partnerID=40\&md5=f53b72a7e6ff6db6e174f5f64d7a9d27}, author = {Almeida, P.L.a , Godinho, M.H.a , Cidade, M.T.a , Nunes, P.a , Marques, A.a , Martins, R.a , Fortunato, E.a , Figueirinhas, J.L.} } @article {Ferreira2002261, title = {Composition and structure of silicon-carbide alloys obtained by hot wire and hot wire plasma assisted techniques}, journal = {Vacuum}, volume = {64}, number = {3-4}, year = {2002}, note = {

cited By 9

}, pages = {261-266}, abstract = {

In this work we present results concerning the composition and structure of intrinsic thin film silicon carbide alloys obtained by hot wire and hot wire plasma assisted techniques using ethylene as carbon gas source. The data show that by increasing the percentage of ethylene in the gas mixture from 14\% to 60\% the optical band gap is enhanced from 1.8 eV to 2.3 eV, for films produced by hot wire technique at a filament temperature of 2123K (1850{\textdegree}C). This is attributed to the increase of carbon incorporation, which was confirmed by the infrared spectra data where an increase is observed in the SiC stretching vibration mode ascribed to the peak located at around 750cm-1. On the other hand, the films produced by combining hot wire and rf plasma show a more efficient carbon incorporation. The SEM photographs of samples produced with hot wire technique reveal an amorphous structure, confirmed by micro-Raman spectroscopy data, while the samples produced with plasma assisting the process show a granular structure with grain sizes in the range of 100-200nm. {\textcopyright} 2002 Elsevier Science Ltd. All rights reserved.

}, doi = {10.1016/S0042-207X(01)00296-2}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036135047\&partnerID=40\&md5=65ede1cc5708e2a64db474378a9473af}, author = {Ferreira, I., Cabrita, A., Fortunato, E., Martins, R.} } @article {Martins2004100, title = {Composition, structure and optical characteristics of polymorphous silicon films deposited by PECVD at 27.12 MHz}, journal = {Materials Science Forum}, volume = {455-456}, year = {2004}, note = {

cited By 1

}, pages = {100-103}, abstract = {

This paper presents data concerning the composition structure and optical characteristics of polymorphous silicon films produced by plasma enhanced chemical vapour deposition at 27.12 MHz and determined respectively by infrared spectrometry, micro Raman, exodiffusion and spectroscopic ellipsometry measurements. When compared to the pm-Si:H films produced at 13.56 MHz, the films produced at 27.12 MHz present hydrogen contents in the range of 21 at\%, the sharp peak ascribed to the exodifusion measurements is shifted towards high temperatures and the imaginary part of the dielectric function 〈ε2〉 is larger and shifted to high energies. Apart from that the peaks of the infrared spectra ascribed to the stretching modes shift towards high wave numbers and the half width of the micro Raman peaks shrinks, meaning that the films produced at 27.12 MHz are more compact and dense.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-3142669762\&partnerID=40\&md5=6a533a932fbdae4167b4193ed671e905}, author = {Martins, R.a , {\'A}guas, H.a , Ferreira, I.a , Fortunato, E.a , Raniero, L.a , Roca i Cabarrocas, P.b} } @article {Martins20061471, title = {Conditions to prepare PPy/Al2O3/Al used as a solid-state capacitor from aqueous malic solutions}, journal = {Journal of Power Sources}, volume = {160}, number = {2 SPEC. ISS.}, year = {2006}, note = {

cited By 12

}, pages = {1471-1479}, abstract = {

The electrosynthesis of polypyrrole (PPy) has been achieved on aluminium in aqueous medium of malic acid by means of cyclic voltammetry, potentiostatic and galvanostatic techniques. Scanning electron microscopy (SEM) and X-ray microanalysis by dispersion energy spectroscopy (EDS) applying on surfaces show that the PPy coating is developed from the metal surface through the cracks of the initial Al2O3 layer. Moreover, the results reveal that the homogeneity of the film achieved increases with the time of electropolymerization. A mechanism involving the participation of the supporting electrolyte and the pyrrole (Py) in distinct active sites was proposed based on the linear sweep voltammetry. It is observed for all the applied electrochemical techniques that the pyrrole concentration has to be higher than 0.1 M to allow the polypyrrole electrodeposition in acid medium. Scanning electron microscopy, secondary electrons (SE) and backscattering electrons (BE), shows that the PPy coating obtained in galvanostatic and potentiostatic modes starts with small islands at weak applied potentials or current densities. The corrosion results in 3\% NaCl medium show that the PPy coating decreases the corrosion behaviour of the aluminium. The bilayer Al2O3/PPy shows a capacitor with future applications. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jpowsour.2006.03.020}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33748967805\&partnerID=40\&md5=5d141cc311d3b4b32dbb06930be6cbbb}, author = {Martins, J.I.a , Costa, S.C.a , Bazzaoui, M.a , Gon{\c c}alves, G.b , Fortunato, E.b , Martins, R.b} } @article {{\'A}guas2001185, title = {Correlation between a-Si:H surface oxidation process and the performance of MIS structures}, journal = {Thin Solid Films}, volume = {383}, number = {1-2}, year = {2001}, note = {

cited By 7

}, pages = {185-188}, abstract = {

In order to correlate the MIS devices performance with different surface oxidation methods, AFM, spectroscopic ellipsometry and infrared spectroscopy measurements were performed in a-Si:H films, before and after surface oxidation, using different oxidation techniques and oxides: thermal dry (in air), wet (in H2O2) and by oxygen plasma, while MIS (metal-insulator-semiconductor) devices were characterized by I-V curves, under dark and AM1.5 illumination conditions. The a-Si:H films were grown by the PECVD technique, in a modified triode configuration reactor to allow a precise control of the ion bombardment during the film deposition. We found that the growth of a thin layer of oxide by chemical processes on the top of the a-Si:H surface can cause changes on the surface morphology that are reflected in the electrical behaviour of the devices. The oxygen plasma treatment, cause the rearrangement of the surface atoms leading to a change of their morphology and to the improvement of the electrical properties of the surface for a MIS applications.

}, doi = {10.1016/S0040-6090(00)01605-9}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035246805\&partnerID=40\&md5=1a4faa61790b680c37f890d0ee25013d}, author = {{\'A}guas, H.a , Nunes, Y.b , Fortunato, E.a , Gordo, P.b , Maneira, M.b , Martins, R.a} } @article {Martins2001101, title = {Correlation between the carbon and hydrogen contents with the gas species and the plasma impedance of silicon carbide films produced by PECVD technique}, journal = {Applied Surface Science}, volume = {184}, number = {1-4}, year = {2001}, note = {

cited By 0

}, pages = {101-106}, abstract = {

This paper deals with the determination of plasma impedance and ion density in r.f. plasmas using different mixtures of silane with methane or ethylene and r.f. powers. The aim is to correlate these parameters with carbon and hydrogen contents of the films produced. The data achieved show that the best carbon incorporation is achieved using ethylene gas mixtures, under low gas mixture concentration, where the substrate also sustains a low ion bombardment. The data also show that particulates in the plasma can be more easily formed in the ethylene-based processes. {\textcopyright} 2001 Published by Elsevier Science B.V.

}, doi = {10.1016/S0169-4332(01)00483-4}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035852198\&partnerID=40\&md5=e2ca051150bd866def1dd7ec63d64cc9}, author = {Martins, R., Silva, V., �?guas, H., Cabrita, A., Ferreira, I., Fortunato, E.} } @article {Lopes20011349, title = {Correlation between the microscopic and macroscopic characteristics of SnO2 thin film gas sensors}, journal = {International Journal of Inorganic Materials}, volume = {3}, number = {8}, year = {2001}, note = {

cited By 5

}, pages = {1349-1351}, abstract = {

Hall effect measurements have been used to evaluate the conduction mechanism, exhibited by tin oxide thin film gas sensors deposited by spray pyrolysis. Two experiments have been carried out: (i) Hall measurements in air and (ii) in the presence of methane (first results reported), both as a function of temperature. From the measurements performed it was possible to infer the potential barrier and its dependence with the atmosphere used. The results obtained for the carrier concentration and mobility have been analysed in the light of the oxygen diffusion mechanism at grain boundaries by using the grain boundary-trapping model. In the presence of the methane gas the electrical resistivity decreases due to the lowering of the inter-grain boundary barrier height. {\textcopyright} 2001 Published by Elsevier Science Ltd.

}, doi = {10.1016/S1466-6049(01)00160-X}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035208785\&partnerID=40\&md5=6bc97140eef5cbab24ad760cd7949098}, author = {Lopes, A.a , Fortunato, E.a , Nunes, P.a , Vilarinho, P.b , Martins, R.a} } @article {Pereira2007104, title = {Corrigendum to "Nickel assisted metal induced crystallization of silicon: Effect of native silicon oxide layer" [Thin Solid Films 511-512 (2006) 275-279] (DOI:10.1016/j.tsf.2005.12.005)}, journal = {Thin Solid Films}, volume = {516}, number = {1}, year = {2007}, note = {

cited By 5

}, pages = {104-105}, abstract = {n/a}, doi = {10.1016/j.tsf.2007.06.001}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34848905902\&partnerID=40\&md5=ca23e15f8538252b31ddd5d09af4cfc8}, author = {Pereira, L.a , Martins, R.M.S.b , Schell, N.b , Fortunato, E.a , Martins, R.a} } @article {G-Berasategui2015256, title = {Corrosion resistance analysis of aluminium-doped zinc oxide layers deposited by pulsed magnetron sputtering}, journal = {Thin Solid Films}, volume = {594}, year = {2015}, note = {

cited By 1

}, pages = {256-260}, abstract = {

In this paper an exhaustive analysis is performed on the electrochemical corrosion resistance of Al-doped ZnO (AZO) layers deposited on silicon wafers by a DC pulsed magnetron sputtering deposition technique to test layer durability. Pulse frequency of the sputtering source was varied and a detailed study of the electrochemical corrosion response of samples in the presence of a corrosive chloride media (NaCl 0.06 M) was carried out. Electrochemical impedance spectroscopy measurements were performed after reaching a stable value of the open circuit at 2 h, 192 h and 480 h intervals. Correlation of the corrosion resistance properties with the morphology, and the optical and electrical properties was tested. AZO layers with transmission values higher than 84\% and resistivity of 6.54 {\texttimes} 10- 4 {\^a}. cm for a deposition process pressure of 3 {\texttimes} 10- 1 Pa, a sputtering power of 2 kW, a pulse frequency of 100 kHz, with optimum corrosion resistance properties, were obtained. {\textcopyright} 2015 Elsevier B.V.

}, doi = {10.1016/j.tsf.2015.07.010}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84947283156\&partnerID=40\&md5=d65ff087518bcd2d3189ea2ec2d7b62b}, author = {G-Berasategui, E.a , Bay{\'o}n, R.a , Zubizarreta, C.a , Barriga, J.a , Barros, R.b , Martins, R.b , Fortunato, E.b} } @article {Gon{\c c}alves20081374, title = {Crystallization of amorphous indium zinc oxide thin films produced by radio-frequency magnetron sputtering}, journal = {Thin Solid Films}, volume = {516}, number = {7}, year = {2008}, note = {

cited By 32

}, pages = {1374-1376}, abstract = {

In this work we studied indium zinc oxide (IZO) thin films deposited by r.f. magnetron sputtering at room temperature. The films were annealed at high temperature (1100~K) in vacuum, and the oxygen exodiffusion was monitored in-situ. The results showed three main peaks, one at approximately 600~K, other at approximately 850~K and the last one at 940~K, which are probably from oxygen bonded in the film surface and in the bulk, respectively. The initial amorphous structure becomes microcrystalline, according to the X-ray diffraction. The electrical conductivity of the films decreases (about 3 orders of magnitude), after the annealing treatment. This behavior could be explained by the crystallization of the structure, which affects the transport mechanism. Apart from the changes in the material structure, a small variation was observed on the absorption coefficient. {\textcopyright} 2007 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2007.03.087}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-38649138034\&partnerID=40\&md5=15ba5c5832ac96297e9f2d5b30213be4}, author = {Gon{\c c}alves, G., Barquinha, P., Raniero, L., Martins, R., Fortunato, E.} } @article {Martins2013657, title = {Curcuminoid content and antioxidant activity in spray dried microparticles containing turmeric extract}, journal = {Food Research International}, volume = {50}, number = {2}, year = {2013}, note = {

cited By 17

}, pages = {657-663}, abstract = {

Curcuma longa L., also known as turmeric, is widely used as a food colorant and has been reported to have antioxidant, anti-inflammatory, anti-mutagenic and anti-cancer properties. The aim of this study was to evaluate the effects of the spray drying on curcuminoid and curcumin contents, antioxidant activity, process yield, the morphology and solubility of the microparticulated solid dispersion containing curcuma extract using a Box Behnken design. The microparticles were spherical in shape, and an increase in outlet temperature from 40 to 80 {\textdegree}C resulted in a significant increase in the yield of microparticles from 16 to 53\%. The total curcuminoid content (17.15 to 19.57. mg/g), curcumin content (3.24 to 4.25. mg/g) and antioxidant activity (530.1 to 860.3 μg/mL) were also affected by the spray drying process. The solubility of curcuminoid from C. longa remarkably improved 100-fold in the microparticles, confirming the potential of the ternary solid dispersion technique to improve the dyeing and nutraceutical properties of these compounds. Furthermore, the microparticles were obtained using the spray drying process, can be easily scaled up. {\textcopyright} 2011 Elsevier Ltd.

}, doi = {10.1016/j.foodres.2011.06.030}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84874350906\&partnerID=40\&md5=6c949123535edcfbd1c98b67098e35a6}, author = {Martins, R.M., Pereira, S.V., Siqueira, S., Salom{\~a}o, W.F., Freitas, L.A.P.} } @article {Nandy201311699, title = {Current transport mechanism at metal-semiconductor nanoscale interfaces based on ultrahigh density arrays of p-type NiO nano-pillars}, journal = {Nanoscale}, volume = {5}, number = {23}, year = {2013}, note = {

cited By 5

}, pages = {11699-11709}, abstract = {

The present work focuses on a qualitative analysis of localised I-V characteristics based on the nanostructure morphology of highly dense arrays of p-type NiO nano-pillars (NiO-NPs). Vertically aligned NiO-NPs have been grown on different substrates by using a glancing angle deposition (GLAD) technique. The preferred orientation of as grown NiO-NPs was controlled by the deposition pressure. The NiO-NPs displayed a polar surface with a microscopic dipole moment along the (111) plane (Tasker{\textquoteright}s type III). Consequently, the crystal plane dependent surface electron accumulation layer and the lattice disorder at the grain boundary interface showed a non-uniform current distribution throughout the sample surface, demonstrated by a conducting AFM technique (c-AFM). The variation in I-V for different points in a single current distribution grain (CD-grain) has been attributed to the variation of Schottky barrier height (SBH) at the metal-semiconductor (M-S) interface. Furthermore, we observed that the strain produced during the NiO-NPs growth can modulate the SBH. Inbound strain acts as an external field to influence the local electric field at the M-S interface causing a variation in SBH with the NPs orientation. This paper shows that vertical arrays of NiO-NPs are potential candidates for nanoscale devices because they have a great impact on the local current transport mechanism due to its nanostructure morphology. {\textcopyright} 2013 The Royal Society of Chemistry.

}, doi = {10.1039/c3nr03803c}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84887443594\&partnerID=40\&md5=62c843c97257ecfea0f57371943e622e}, author = {Nandy, S., Gon{\c c}alves, G., Pinto, J.V., Busani, T., Figueiredo, V., Pereira, L., Paiva Martins, R.F., Fortunato, E.} } @article {Martins19953481, title = {Dark current-voltage characteristics of transverse asymmetric hydrogenated amorphous silicon diodes}, journal = {Journal of Applied Physics}, volume = {78}, number = {5}, year = {1995}, note = {

cited By 17

}, pages = {3481-3487}, abstract = {

The aim of this work is to provide the basis for the interpretation, under steady state and in the low-voltage regime of the dark current-density-voltage (J-V) characteristics of transverse asymmetric amorphous silicon (a-Si:H) p-i-n and n-i-p diodes. The transverse asymmetric a-Si:H diodes present ratios between the metal contact and the underneath doped layer areas larger than five, leading to the inclusion, in the diode equation, of a lateral leakage current, responsible for the high saturation current density and the forward shape of the J-V curves recorded. The leakage current depends on the lateral spatial potential developed with which varies following a power-law dependence. The experimental J-V curves in diodes with the doped layer around the metal contact unetched and etched prove the role and origin of this lateral leakage current and, thus, the proposed model. {\textcopyright} 1995 American Institute of Physics.

}, doi = {10.1063/1.359980}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-36449002034\&partnerID=40\&md5=7aa540c6855c52a6d1abeb05864039eb}, author = {Martins, R., Fortunato, E.} } @article {Martins19971, title = {Dependence of amorphous silicon solar cell performances on the lateral drift current}, journal = {Solar Energy Materials and Solar Cells}, volume = {45}, number = {1}, year = {1997}, note = {

cited By 3

}, pages = {1-15}, abstract = {

The aim of this work is to present a model able to explain the role of the lateral drift current on the experimental behaviour exhibited by p-i-n amorphous silicon solar cells (J-V characteristics, responsivity and the apparent device degradation behaviour), when the ratio between the covered and uncovered metal collected areas of the device is higher than one or recrystallization occurs in the edges of the p-i-n junction.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030735407\&partnerID=40\&md5=a327f5523e7be6a0f00475654a99d5b8}, author = {Martins, R., Bicho, A., Lavareda, G., Fortunato, E.} } @article {Fortunato2002612, title = {Dependence of the strains and residual mechanical stresses on the performances presented by a-Si:H thin film position sensors}, journal = {Advanced Engineering Materials}, volume = {4}, number = {8}, year = {2002}, note = {

cited By 8

}, pages = {612-616}, abstract = {

The influence of residual stresses on the performances of large area position sensitive detectors produced on flexible substrates are presented here. For evaluating the residual stresses, two main techniques were used: An active optical triangulation and angle resolved scattering and the constant photocurrent method (CPM). From the results it was possible to correlate the stresses and the density of defects present in the films.

}, doi = {10.1002/1527-2648(20020806)4:8<612::AID-ADEM612>3.0.CO;2-U}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036671949\&partnerID=40\&md5=ba0249303b4827d97d371033ce3f19ab}, author = {Fortunato, E.a , Brida, D.a , Pereira, L.a , {\'A}guas, H.a , Silva, V.a , Ferreira, I.a , Costa, M.F.M.b , Teixeira, V.b , Martins,} } @article {Mendes2016286, title = {Design of optimized wave-optical spheroidal nanostructures for photonic-enhanced solar cells}, journal = {Nano Energy}, volume = {26}, year = {2016}, note = {

cited By 0

}, pages = {286-296}, abstract = {

The interaction of light with wavelength-sized photonic nanostructures is highly promising for light management applied to thin-film photovoltaics. Several light trapping effects come into play in the wave optics regime of such structures that crucially depend on the parameters of the photonic and absorbing elements. Thus, multi-parameter optimizations employing exact numerical models, as performed in this work, are essential to determine the maximum photocurrent enhancement that can be produced in solar cells.Generalized spheroidal geometries and high-index dielectric materials are considered here to model the design of the optical elements providing broadband absorption enhancement in planar silicon solar cells. The physical mechanisms responsible for such enhancement are schematized in a spectral diagram, providing a deeper understanding of the advantageous characteristics of the optimized geometries. The best structures, composed of TiO2 half-spheroids patterned on the cells{\textquoteright} top surface, yield two times higher photocurrent (up to 32.5 mA/cm2 in 1.5 μm thick silicon layer) than the same devices without photonic schemes.These results set the state-of-the-art closer to the theoretical Lambertian limit. In addition, the considered light trapping designs are not affected by the traditional compromise between absorption enhancement versus current degradation by recombination, which is a key technological advantage. {\textcopyright} 2016 Elsevier Ltd.

}, doi = {10.1016/j.nanoen.2016.05.038}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973459206\&partnerID=40\&md5=0b72ad02577b8e5a403a37a73e9b2b08}, author = {Mendes, M.J., Ara{\'u}jo, A., Vicente, A., {\'A}guas, H., Ferreira, I., Fortunato, E., Martins, R.} } @article {Raniero2007575, title = {Differences between amorphous and nanostructured silicon films and their application in solar cell}, journal = {High Temperature Material Processes}, volume = {11}, number = {4}, year = {2007}, note = {

cited By 2

}, pages = {575-583}, abstract = {

Nanostructured silicon thin films were produced in a single PECVD (Plasma Enhanced Chemical Vapour Deposition) reactor using an excitation frequency of 27.12 MHz. The process parameters were selected to allow the films{\textquoteright} production to be performed at the transition region (from amorphous to microcrystalline), aiming their use in solar cells. The real and imaginary parts of pseudo-dielectric function of these nanostructured films show a shift to higher energies and the order factor reveals an improvement on the short atomic range order of the films produced. The solar cells with a structure of ZGO/p-a-SiC:H/buffer1/buffer2/i-(nc/a-Si:H)/n-a-Si:H/Ag/Al were deposited with nanostructured intrinsic layer, showing a good performances, with current densities of about 14.48 mA/cm2, open circuit voltage of 0.94 V, and fill factor of 0.67, which lead to efficiencies of 9.12\%. The solar cell degradation study performed under AM1.5 spectrum conditions up to 100 hours revealed a decrease on the solar cell efficiency of about 8.11\%, mainly related to the decreasing of current density. Despite that, the open circuit voltage increases slightly after the degradation.

}, doi = {10.1615/HighTempMatProc.v11.i4.90}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-38349052909\&partnerID=40\&md5=3e970b8948a216c8d03ef37b4dd621e2}, author = {Raniero, L.a , Ferreira, I.b , Fortunato, E.b , Martins, R.b} } @article {Zhang2004188, title = {The diphasic nc-Si/a-Si:H thin film with improved medium-range order}, journal = {Journal of Non-Crystalline Solids}, volume = {338-340}, number = {1 SPEC. ISS.}, year = {2004}, note = {

cited By 16

}, pages = {188-191}, abstract = {

A series of silicon film samples were prepared by plasma enhanced chemical vapor deposition (PECVD) near the threshold from amorphous to nanocrystalline state by adjusting the plasma parameters and properly increasing the reactions between the hydrogen plasma and the growing surface. The microstucture of the films was studied by micro-Raman and Fourier transform infrared (FTIR) spectroscopy. The influences of the hydrogen dilution ratio of silane (R H = [H2]/[SiH4]) and the substrate temperature (Ts) on the microstructural and photoelectronic properties of silicon films were investigated in detail. With the increase of RH from 10 to 100, a notable improvement in the medium-range order (MRO) of the films was observed, and then the phase transition from amorphous to nanocrystalline phase occurred, which lead to the formation of diatomic hydrogen complex, H 2 * and their congeries. With the increase of T s from 150 to 275 {\textdegree}C, both the short-range order and the medium range order of the silicon films are obviously improved. The photoconductivity spectra and the light induced changes of the films show that the diphasic nc-Si/a-Si:H films with fine medium-range order present a broader light spectral response range in the longer wavelength and a lower degradation upon illumination than conventional a-Si:H films. {\textcopyright} 2004 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2004.02.050}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-2942555273\&partnerID=40\&md5=8a1f15f9591631b0fd931d96aa5c4cf5}, author = {Zhang, S.a b , Liao, X.a , Xu, Y.a , Martins, R.b , Fortunato, E.b , Kong, G.a} } @article {Baptista2015278, title = {Down conversion photoluminescence on PVP/Ag-nanoparticles electrospun composite fibers}, journal = {Optical Materials}, volume = {39}, year = {2015}, note = {

cited By 1

}, pages = {278-281}, abstract = {

The influence of Ag nanoparticles (Ag NPs) on the luminescence of electrospun nonwoven mats made of polyvinylpyrrolidone (PVP) has been studied in this work. The PVP fibers incorporating 2.1-4.3 nm size Ag NPs show a significant photoluminescence (PL) band between 580 and 640 nm under 325 nm laser excitation. The down conversion luminescence emission is present even after several hours of laser excitation, which denotes the durability and stability of fibers to consecutive excitations. As so these one-dimensional photonic fibers made using cheap methods is of great importance for organic optoelectronic applications, fluorescent clothing or counterfeiting labels. {\textcopyright} 2014 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.optmat.2014.11.015}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84918803547\&partnerID=40\&md5=3920bdfa72e5b01614001fa973a01ddd}, author = {Baptista, A.C.a , Botas, A.M.b , Almeida, A.P.C.a , Nicolau, A.T.a , Falc{\~a}o, B.P.b , Soares, M.J.b , Leit{\~a}o, J.P.b , Martins, R.} } @article {Fernandes200486, title = {Dynamic characterization of large area image sensing structures based on a-SiC:H}, journal = {Materials Science Forum}, volume = {455-456}, year = {2004}, note = {

cited By 0

}, pages = {86-90}, abstract = {

The working principle of silicon p-i-n structures with low conductivity (σd) doped layers as single element image sensors is based on the modulation, by the local illumination conditions of the photocurrent generated by a light beam scanning the active area of the device. A higher sensitivity is achieved using a wide band gap a-Si:C alloy in the doped layers, improving the light penetration into the intrinsic semiconductor and reducing the lateral currents in the structure, which are responsible by an image smearing effect observed in sensors with high σd doped layers. This work focuses on the transient response of such sensor and on the role of the carbon (C) content of the doped layers. A set of devices with different percentage of C incorporation in the doped layers is analyzed by measuring the scanner-induced photocurrent under different bias conditions, (ranging from -1.5V to 1V) in order to evaluate the response time.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17144446338\&partnerID=40\&md5=03d9a19aa9fbfb1ee883cbe86c414cc2}, author = {Fernandes, M.a , Vieira, M.a , Martins, R.b} } @article {Liu20164478, title = {Eco-friendly, solution-processed In-W-O thin films and their applications in low-voltage, high-performance transistors}, journal = {Journal of Materials Chemistry C}, volume = {4}, number = {20}, year = {2016}, note = {

cited By 1

}, pages = {4478-4484}, abstract = {

In this study, amorphous indium-tungsten oxide (IWO) semiconductor thin films were prepared by an eco-friendly spin-coating process using ethanol and water as solvents. The electrical properties of IWO thin-film transistors (TFTs), together with the structural and morphological characteristics of IWO thin films, were systematically investigated as functions of tungsten concentration and annealing temperature. The optimized IWO channel layer was then integrated on an aqueous aluminum oxide (AlOx) gate dielectric. It is observed that the solution-processed IWO/AlOx TFT presents high stability and improved characteristics, such as an on/off current ratio of 5 {\texttimes} 107, a field-effect mobility of 15.3 cm2 V-1 s-1, a small subthreshold slope of 68 mV dec-1, and a threshold voltage shift of 0.15 V under bias stress for 2 h. The IWO/AlOx TFT could be operated at a low voltage of 2 V, which was 15 times lower than that of conventional SiO2-based devices. The solution-processed IWO thin films synthesized in a green route would be promising candidates for large-area and high-performance low-cost devices. {\textcopyright} The Royal Society of Chemistry 2016.

}, doi = {10.1039/c6tc00474a}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971278335\&partnerID=40\&md5=95bed5c7f72e9f9f301439a6699c9dfa}, author = {Ao Liu, Guoxia Liu, Huihui Zhu, Byoungchul Shin, Elvira Fortunato,Rodrigo Martins and Fukai Shan} } @article {{\'A}guas2004810, title = {Effect of an interfacial oxide layer in the annealing behaviour of Au/a-Si:H MIS photodiodes}, journal = {Journal of Non-Crystalline Solids}, volume = {338-340}, number = {1 SPEC. ISS.}, year = {2004}, note = {

cited By 2

}, pages = {810-813}, abstract = {

This work presents a study on the effect of an interfacial silicon oxide layer placed between Au and a-Si:H MIS (metal-insulator-semiconductor) photodiodes in their performances, by stopping the Au diffusion towards the a-Si:H. The results show that the Au diffuses very easily to the oxide free a-Si:H surface, even at room temperature, degrading the photodiode performance. On the other hand, the MIS photodiodes with the interfacial oxide show an improvement of their characteristics after annealing, function of its thickness, and degree of film{\textquoteright}s compactness. This effect is associated with the presence of oxide of thicknesses >=5 {\r A} at the Au/a-Si:H interface that prevents the Au diffusion and improves the photodiode characteristics, which does not happen when the interfacial oxide is absent. {\textcopyright} 2004 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2004.03.097}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-2942588791\&partnerID=40\&md5=ca9605e4c488f6ff4df73c88e28f4c91}, author = {{\'A}guas, H.a , Pereira, L.a , Ferreira, I.a , Ramos, A.R.b , Viana, A.S.c , Andreu, J.d , Vilarinho, P.e , Fortunato, E.a , Martin} } @article {Aguas200496, title = {Effect of annealing on gold rectifying contacts in amorphous silicon}, journal = {Materials Science Forum}, volume = {455-456}, year = {2004}, note = {

cited By 1

}, pages = {96-99}, abstract = {

This work presents a study performed on several Au contacts deposited by evaporation on oxide free and oxidised (5-20{\r A} of oxide) a-Si:H surfaces. The characterisation of the films was performed on as deposited, aged and annealed at 150{\textdegree}C structures. SIMS and RBS measurements show that the Au diffuses very easily on oxide free a-Si:H surfaces, even at room temperature, resulting in the formation of an oxide at the device surface that acquires a blue colour instead of the gold colour of the contacts. This was also visible in the SEM pictures of the cross section of the structures produced and on the changes of the surface morphology observed by AFM measurements. On the other hand, when the Au is deposited on oxidised a-Si:H surfaces, the results show that the oxide prevents the Au from diffusing and the nature of the contact is preserved. That is, better rectifying and stability performances are obtained in MIS like structures than in Schottky structures.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17144433524\&partnerID=40\&md5=1db3d8758ea95ed533857d6c3dc87691}, author = {Aguas, H.a , Pereira, L.a , Ferreira, I.a , Ramos, A.R.b , Viana, A.S.c , Andreu, J.d , Vilarinho, P.e , Fortunato, E.a , Martin} } @article {Elangovan20081489, title = {Effect of annealing on molybdenum doped indium oxide thin films RF sputtered at room temperature}, journal = {Vacuum}, volume = {82}, number = {12}, year = {2008}, note = {

cited By 7

}, pages = {1489-1494}, abstract = {

Thin films of molybdenum doped indium oxide (IMO) were deposited on glass at room temperature using an in-built three-source RF magnetron sputtering. The films were studied as a function of oxygen volume percentage (O2 vol. \%; ranging from 0.0 to 17.5\%) in the sputtering chamber. The as-deposited amorphous films were crystallized on post-annealing. The as-deposited films are low conducting and Hall coefficients were undetectable; whereas post-annealed films possess fairly high conductivity. The lowest transmittance (11.96\% at 600 nm) observed from the films deposited without oxygen increased to a maximum of 88.01\% (3.5 O2 vol. \%); whereas this transmittance was decreased with the increasing O2 vol. \% to as low as 81.04\% (15.6 O2 vol. \%); a maximum of 89.80\% was obtained from the films annealed at 500 {\textdegree}C in open air (3.5 O2 vol. \%). The optical band gap of 3.80 eV obtained from the films deposited without oxygen increased with increasing O2 vol. \% to as high as 3.91 eV (17.5 O2 vol. \%). A maximum of 3.92 eV was obtained from the films annealed at 300 {\textdegree}C in N2:H2 gas atmosphere (17.5 O2 vol. \%). {\textcopyright} 2008 Elsevier Ltd. All rights reserved.

}, doi = {10.1016/j.vacuum.2008.03.005}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-49349088879\&partnerID=40\&md5=8cd666bae43b4f2d68f027457b7b5aed}, author = {Elangovan, E., Marques, A., Pimentel, A., Martins, R., Fortunato, E.} } @article {Wang20087178, title = {Effect of annealing on the properties of N-doped ZnO films deposited by RF magnetron sputtering}, journal = {Applied Surface Science}, volume = {254}, number = {22}, year = {2008}, note = {

cited By 22

}, pages = {7178-7182}, abstract = {

N-doped ZnO films were deposited by RF magnetron sputtering in N2/Ar gas mixture and were post-annealed at different temperatures (Ta) ranging from 400 to 800 {\textdegree}C in O2 gas at atmospheric pressure. The as-deposited and post-annealed films were characterized by their structural (XRD), compositional (SIMS, XPS), optical (UV-vis-NIR spectrometry), electrical (Hall measurements), and optoelectronic properties (PL spectra). The XRD results authenticate the improvement of crystallinity following post-annealing. The weak intensity of the (0 0 2) reflection obtained for the as-deposited N-doped ZnO films was increased with the increasing Ta to become the preferred orientation at higher Ta (800 {\textdegree}C). The amount of N-concentration and the chemical states of N element in ZnO films were changed with the Ta, especially above 400 {\textdegree}C. The average visible transmittance (400-800 nm) of the as-deposited films (26\%) was increased with the increasing Ta to reach a maximum of 75\% at 600 {\textdegree}C but then decreased. In the PL spectra, A0X emission at 3.321 eV was observed for Ta = 400 {\textdegree}C besides the main D0X emission. The intensity of the A0X emission was decreased with the increasing Ta whereas D0X emission became sharper and more optical emission centers were observed when Ta is increased above 400 {\textdegree}C. {\textcopyright} 2008 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.apsusc.2008.05.321}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-50849129137\&partnerID=40\&md5=a2fefd1af12d7d7f0967c947844543d3}, author = {Wang, J.a , Elamurugu, E.a , Sallet, V.b , Jomard, F.b , Lusson, A.b , Rego, A.M.B.d.c , Barquinha, P.a , Gon{\c c}alves, G.a , Marti} } @article {Elangovan20082831, title = {Effect of annealing on the properties of RF sputtered indium molybdenum oxide thin films}, journal = {Journal of Non-Crystalline Solids}, volume = {354}, number = {19-25}, year = {2008}, note = {

cited By 1

}, pages = {2831-2838}, abstract = {

Indium molybdenum oxide thin films radio-frequency sputtered at room temperature on glass were studied as a function of oxygen volume percentage. The as-deposited films were post-annealed in the temperature range of 300-500 {\textdegree}C in oxidizing (open air) and reducing (N2:H2 gas) atmospheres for 1 h. The as-deposited amorphous films become crystalline on post-annealing irrespective of the annealing conditions. In most cases, the (2 2 2) diffraction line is emerged as the high intensive peak. The films annealed at >=400 {\textdegree}C in N2:H2 show a carrier concentration \>1020 cm-3. The better electrical properties are obtained for the films post-annealed at 300 {\textdegree}C. The optical transmittance of the as-deposited films varies between 10\% and 85\% depending on the deposition and annealing conditions. Atomic force microscope analysis reveal that the films annealed at 300 {\textdegree}C are composed of closely packed crystallites (size of which varies between 5 nm and 150 nm) whose size varies noticeably when the annealing temperature is raised to 400 {\textdegree}C. On the other hand, the surface of the films annealed at 500 {\textdegree}C becomes rougher, with the RMS roughness varying between 2.00 nm and 16.97 nm. The surface of the films deposited in the presence of oxygen shows metal like features when annealed at >=400 {\textdegree}C in N2:H2 that is attributed to the segregation of indium. Further, the segregation of In is substantiated from the scanning electron microscope analysis of these samples. {\textcopyright} 2008 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2007.12.015}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-43049146502\&partnerID=40\&md5=010b36ba85966b0b81f6e6a524439994}, author = {Elangovan, E., Martins, R., Fortunato, E.} } @article {Barquinha20078450, title = {Effect of annealing temperature on the properties of IZO films and IZO based transparent TFTs}, journal = {Thin Solid Films}, volume = {515}, number = {24 SPEC. ISS.}, year = {2007}, note = {

cited By 71

}, pages = {8450-8454}, abstract = {

This work shows the effect of the annealing temperature and atmosphere on the properties of r.f. magnetron sputtered indium-zinc oxide (IZO) thin-films of two types: one a conductive film (as-deposited, room temperature) that exhibits a resistivity of 3.5 {\texttimes} 10- 4~Ω cm; the other, a semiconductor film with a resistivity \~{} 102~Ω cm. The annealing temperatures were changed between 125 and 500~{\textdegree}C. Crystallization of the more conductive films was already noticeable at temperatures around 400~{\textdegree}C. Three different annealing atmospheres were used - vacuum, air and oxygen. For the conductive films, only the oxygen atmosphere was critical, leading to an increase of the electrical resistivity of more than one order of magnitude, for temperatures of 250~{\textdegree}C and above. Concerning the semiconductor films, both temperature and atmosphere had a strong effect on the film{\textquoteright}s properties, and the resistivity of the annealed films was always considerably smaller than the as-deposited films. Finally, some results of the application of these films to transparent TFTs are shown. {\textcopyright} 2007 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2007.03.176}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34548852584\&partnerID=40\&md5=28eaf05ad2511617ecfbab8d7ad0b5a7}, author = {Barquinha, P.a , Gon{\c c}alves, G.a , Pereira, L.b , Martins, R.b , Fortunato, E.a} } @article {Elangovan20078549, title = {Effect of base and oxygen partial pressures on the electrical and optical properties of indium molybdenum oxide thin films}, journal = {Thin Solid Films}, volume = {515}, number = {24 SPEC. ISS.}, year = {2007}, note = {

cited By 7

}, pages = {8549-8552}, abstract = {

Indium molybdenum oxide thin films were RF sputtered at room temperature on glass substrates with a reference base pressure of 7.5 {\texttimes} 10- 4~Pa. The electrical and optical properties of the films were studied as a function of oxygen partial pressures (OPP) ranging from 1.5 {\texttimes} 10- 3~Pa to 3.5 {\texttimes} 10- 3~Pa. The obtained data show that the bulk resistivity of the films increased by about 4 orders of magnitude (from 7.9 {\texttimes} 10- 3 to 7.6 {\texttimes} 101~Ω-cm) when the OPP increased from 1.5 {\texttimes} 10-3 to 3.5 {\texttimes} 10- 3~Pa, and the carrier concentration decreased by about 4 orders (from 1.77 {\texttimes} 1020 to 2.31 {\texttimes} 1016~cm- 3). On the other hand, the average visible transmittance of 30.54\% of the films (brown colour; OPP = 1.5 {\texttimes} 10- 3~Pa) was increased with increasing OPP to a maximum of 80.47\% (OPP = 3.5 {\texttimes} 10- 3~Pa). The optical band gap calculated from the absorption edge of the transmittance spectra ranges from 3.77 to 3.88~eV. Further, the optical and electrical properties of the films differ from those deposited at similar conditions but with a base pressure lower than 7.5 {\texttimes} 10- 4~Pa. {\textcopyright} 2007 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2007.03.127}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34548859521\&partnerID=40\&md5=ae76f8075ab8c9b24ddcf7813daaecdf}, author = {Elangovan, E., Martins, R., Fortunato, E.} } @article {Barquinha2008, title = {The effect of deposition conditions and annealing on the performance of high-mobility GIZO TFTs}, journal = {Electrochemical and Solid-State Letters}, volume = {11}, number = {9}, year = {2008}, note = {

cited By 83

}, pages = {H248-H251}, abstract = {

The influence of oxygen content, radio-frequency (rf) sputtering power, and postdeposition annealing on the electrical properties of gallium-indium-zinc oxide (GIZO) thin-film transistors (TFTs) is analyzed. Little to no oxygen content in the sputtering chamber is crucial to obtain high-performance devices, even before annealing. In contrast, a high oxygen content and rf power lead, respectively, to unstable/poor performing and depletion mode TFTs before annealing, and mainly for these "nonideal" conditions, annealing proves to be effective to improve device performance/stability and to decrease the performance discrepancy among TFTs processed under different oxygen and rf power conditions. Best TFTs present a field-effect mobility of 46 cm2 / V s, subthreshold swing of 0.26 V/dec, threshold voltage of 0.70 V, and an on/off ratio 108 - 109. These results are a consequence of the optimized processing and of the usage of proper GIZO target composition, 1:2:1 mol. {\textcopyright} 2008 The Electrochemical Society.

}, doi = {10.1149/1.2945869}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-48249116747\&partnerID=40\&md5=016ea0f572b4d7e4791ab3888d2de04f}, author = {Barquinha, P., Pereira, L., Gonalves, G., Martins, R., Fortunato, E.} } @article {Nunes2001151, title = {Effect of deposition conditions upon gas sensitivity of zinc oxide thin films deposited by spray pyrolysis}, journal = {Solid State Phenomena}, volume = {80-81}, year = {2001}, note = {

cited By 0

}, pages = {151-154}, abstract = {

In this work we present the results of a study concerning the role of the properties of zinc oxide thin films deposited by spray pyrolysis on its sensitivity to methane or ethane. It was found that using highly resistive thin layers leads to an increase in the film sensitivity. The variation of the operating temperature of the film leads to a significant change in the sensitivity of the sensor and the ideal operating temperature dependence of the gas used. The sensitivity of the ZnO thin films changes linear with the increase of the gas concentration. However these films seem to be more appropriated for the detection of methane than for ethane since the value of sensitivity obtained are higher and its variation with the gas concentration more pronounced. After the annealing treatment performed the films sensitivity decreases.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034833165\&partnerID=40\&md5=475141dec6808104a341d34a6b995772}, author = {Nunes, P., Fortunato, E., Vilarinho, P., Martins, R.} } @article {Nunes2002281, title = {Effect of different dopant elements on the properties of ZnO thin films}, journal = {Vacuum}, volume = {64}, number = {3-4}, year = {2002}, note = {

cited By 252

}, pages = {281-285}, abstract = {

In this work we studied the influence of the dopant elements and concentration on the properties of ZnO thin film deposited by spray pyrolysis. The results show that the doping affects the thin films properties mainly the electrical ones, function of dopant concentration and nature. The most important changes were observed for films doped with 1at\% of indium which exhibit a resistivity of 1.9 {\texttimes} 10-1 Ωcm associated with a transmitance of 90\%. After the annealing treatment, the resistivity of the film decreases to 5.9 {\texttimes} 10-3 Ωcm without significative changes in the optical properties. The films were also used to produce amorphous silicon solar cells where the best results were obtained for ZnO:In. {\textcopyright} 2002 Elsevier Science Ltd. All rights reserved.

}, doi = {10.1016/S0042-207X(01)00322-0}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036136718\&partnerID=40\&md5=13f355cd078f317bfaa1454817ae1f4b}, author = {Nunes, P.a , Fortunato, E.a , Tonello, P.a , Braz Fernandes, F.a , Vilarinho, P.b , Martins, R.a} } @article {Nunes20011211, title = {Effect of different dopants on the properties of ZnO thin films}, journal = {International Journal of Inorganic Materials}, volume = {3}, number = {8}, year = {2001}, note = {

cited By 16

}, pages = {1211-1213}, abstract = {

The influence of doping on the properties of zinc oxide thin films deposited by spray pyrolysis has been studied. The results show that the doping affects the properties of the films, mainly the electrical ones, function of its concentration and nature. The most significative improvement were observed for films doped with 1 at.\% of indium exhibiting a resistivity of 1.9 {\texttimes} 10-1 Ω m associated to a transmittance of 86\%, characteristics required for applications on the optoelectronic devices. {\textcopyright} 2001 Elsevier Science Ltd. All rights reserved.

}, doi = {10.1016/S1466-6049(01)00129-5}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035208516\&partnerID=40\&md5=676057f7c7ceb6790fe8ec62f4b289b5}, author = {Nunes, P.a , Fortunato, E.a , Vilarinho, P.b , Martins, R.a} } @article {O{\textquoteright}Brien20111174, title = {The effect of dopants on the morphology, microstructure and electrical properties of transparent zinc oxide films prepared by the sol-gel method}, journal = {Thin Solid Films}, volume = {520}, number = {4}, year = {2011}, note = {

cited By 3

}, pages = {1174-1177}, abstract = {

The influence of doping on the morphology, physical and electrical properties of zinc oxide produced by the sol-gel method was examined. Undoped zinc oxide was observed to form relatively porous films. Addition of an Al dopant influenced the sheet resistance, but did not result in a change in morphology, examined by atomic force microscopy when compared to undoped films. In the case of electrical measurements, undoped ZnO films were extremely resistive. A minimum dopant concentration of 2 at.\%. Al was required to produce materials which were more conductive, as observed by sheet resistance measurements, which were shown to vary with annealing temperature. The versatile nature of sol-gel processing was demonstrated by selective ink-jet deposition of sol-gel droplets which were annealed to form oxide materials. {\textcopyright} 2011 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2011.04.210}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-82755189604\&partnerID=40\&md5=6a5dfa132b336c13620678f6dffaf663}, author = {O{\textquoteright}Brien, S.a , {\c C}opuroglu, M.a , Tassie, P.b , Nolan, M.G.a , Hamilton, J.A.a , Povey, I.a , Pereira, L.c , Martins, R.c , Fortun} } @article {Martins2013692, title = {The effect of homogenization method on the properties of carbamazepine microparticles prepared by spray congealing}, journal = {Journal of Microencapsulation}, volume = {30}, number = {7}, year = {2013}, note = {

cited By 5

}, pages = {692-700}, abstract = {

The aim of this study was to investigate the influence of ultrasound and high-shear mixing on the properties of microparticles obtained by spray congealing. Dispersions containing 10\% carbamazepine and 90\% carrier Gelucire{\textregistered} 50/13 (w/w) were prepared using magnetic stirring, high-shear mixing, or ultrasound. Each preparation was made using hot-melt mixing spray congealing to obtain the microparticles. All microparticles presented a spherical shape with high encapsulation efficiency (\>99\%). High-shear mixing and ultrasound promoted a decrease in the size of microparticles (D90) to 62.8 {\textpm} 4.1 μm and 64.9 {\textpm} 3.3 μm, respectively, while magnetic stirring produced microparticles with a size of 84.1 {\textpm} 1.4 μm. The use of ultrasound led to microparticles with increased moisture content as identified through sorption isotherm studies. In addition, rheograms showed distinct rheological behaviour among different dispersion preparations. Therefore, the technique used to prepare dispersions for spray congealing can affect specific characteristics of the microparticles and should be controlled during the preparation. {\textcopyright} 2013 Informa UK Ltd. All rights reserved.

}, doi = {10.3109/02652048.2013.778906}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84885336654\&partnerID=40\&md5=a7a0d145cf45d92af0e28a945bc21121}, author = {Martins, R.M., Siqueira, S., MacHado, M.O., Freitas, L.A.P.} } @article {Parthiban2011, title = {Effect of Li3+ heavy ion irradiation on the Mo doped In2O3 thin films prepared by spray pyrolysis technique}, journal = {Journal of Physics D: Applied Physics}, volume = {44}, number = {8}, year = {2011}, note = {

cited By 3

}, abstract = {

The high visible-near infrared transparent and high carrier mobility (μ) Mo doped (0.5 at\%) indium oxide (IMO) films were deposited by the spray pyrolysis technique. The deposited films were irradiated by 50MeV Li 3+ ions with different fluences of 1{\texttimes}1011, 1{\texttimes}1012 and 1{\texttimes}1013 ions cm-2. X-ray diffraction analysis confirmed the cubic bixbyite structure of indium oxide. A fascinating feature is that the ion irradiation process has introduced a fraction of the molybdenum oxide phase. The μ of as-deposited IMO films is decreased from ̃122.4 to 93.3 cm2 V-1 s-1, following the ion irradiation. The theoretically calculated μ and carrier density values were correlated with those measured experimentally. The transport mechanism has been analysed based on the ionized and neutral impurity scattering centres. The average transmittance (400-2500 nm) of the as-deposited IMO films is decreased from 83\% to 60\% following irradiation. {\textcopyright} 2011 IOP Publishing Ltd.

}, doi = {10.1088/0022-3727/44/8/085404}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79951803236\&partnerID=40\&md5=c5e854fcb698c9a2838da842d4d4e409}, author = {Parthiban, S.a b , Elangovan, E.b , Ramamurthi, K.a , Kanjilal, D.c , Asokan, K.c , Martins, R.b , Fortunato, E.b} } @article {Wang201364, title = {Effect of N and P codoping on ZnO properties}, journal = {Advanced Materials Research}, volume = {645}, year = {2013}, note = {

cited By 2

}, pages = {64-67}, abstract = {

Nitrogen and Phosphorus co-doped (N+P)- zinc oxide (ZnO) films were RF sputtered on corning glass substrates at 350 {\textdegree}C and comparatively studied with undoped, N-, and P- doped ZnO. X-ray diffraction spectra confirmed that the ZnO structure with a preferred orientation along \<002\> direction. Scanning electron microscope analysis showed different microstructure for the N+P co-doping, and thus probably confirming the co-existence of both the dopants. X-ray photoelectron spectroscopy spectra revealed that the chemical composition in N+P co-doped ZnO are different from that found in undoped, N-, and P- doped ZnO. The atomic ratio of N and P in N+P co-doped ZnO is higher than that in single N or P doped ZnO. One broad ZnO emission peak around 420 nm is observed in photoluminescence spectra. The relative intensity of the strongest peak obtained from co-doped ZnO films is about twice than the P- doped and thrice than the pure and N- doped films. {\textcopyright} (2013) Trans Tech Publications, Switzerland.

}, doi = {10.4028/www.scientific.net/AMR.645.64}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84873835970\&partnerID=40\&md5=fe71af00f2b5bcae3cff9d64a20fc4ab}, author = {Wang, J.a , Elamurugu, E.b , Li, H.a , Jiao, S.a , Zhao, L.a , Martins, R.a , Fortunato, E.a} } @article {Gon{\c c}alves200643, title = {Effect of oxidant/monomer ratio on the electrical properties of polypyrrole in tantalum capacitors}, journal = {Materials Science Forum}, volume = {514-516}, number = {PART 1}, year = {2006}, note = {

cited By 5

}, pages = {43-47}, abstract = {

In this work, the relation between oxidant/monomer ratio and the electrical conductivity of polypyrrole was studied using different ratios. We achieved a maximum value for electrical conductivity of 7.5 S/cm for a ratio of 2:1. We also developed a chemical dip-coating process to produce the cathode layer in tantalum capacitors. We obtained capacitances of about 80 μF after 8 cycles using the sequence Monomer/Oxidant.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-37849039158\&partnerID=40\&md5=7a89e57b2f8a4ce03ba56082d88bbfc5}, author = {Gon{\c c}alves, G.a , Fortunato, E.a , Martins, J.b , Martins, R.a} } @article {Figueiredo20083949, title = {Effect of post-annealing on the properties of copper oxide thin films obtained from the oxidation of evaporated metallic copper}, journal = {Applied Surface Science}, volume = {254}, number = {13}, year = {2008}, note = {

cited By 90

}, pages = {3949-3954}, abstract = {

Thin films of copper oxide were obtained through thermal oxidation (100-450 {\textdegree}C) of evaporated metallic copper (Cu) films on glass substrates. The X-ray diffraction (XRD) studies confirmed the cubic Cu phase of the as-deposited films. The films annealed at 100 {\textdegree}C showed mixed Cu-Cu2O phase, whereas those annealed between 200 and 300 {\textdegree}C showed a single cubic Cu2O phase. A single monoclinic CuO phase was obtained from the films annealed between 350 and 450 {\textdegree}C. The positive sign of the Hall coefficient confirmed the p-type conductivity in the films with Cu2O phase. However, a relatively poor crystallinity of these films limited the p-type characteristics. The films with Cu and CuO phases show n-type conductivity. The surface of the as-deposited is smooth (RMS roughness of 1.47 nm) and comprised of uniformly distributed grains (AFM and SEM analysis). The post-annealing is found to be effective on the distribution of grains and their sizes. The poor transmittance of the as-deposited films (\<1\%) is increased to a maximum of \~{}80\% (800 nm) on annealing at 200 {\textdegree}C. The direct allowed band gap is varied between 2.03 and 3.02 eV. {\textcopyright} 2008 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.apsusc.2007.12.019}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-41749086660\&partnerID=40\&md5=1c2ce722bab3688d6c754a89209b3766}, author = {Figueiredo, V.a , Elangovan, E.a , Gon{\c c}alves, G.a , Barquinha, P.a , Pereira, L.a , Franco, N.b , Alves, E.b , Martins, R.a , Fo} } @article {Pimentel2015, title = {Effect of solvents on ZnO nanostructures synthesized by solvothermal method assisted by microwave radiation: a photocatalytic study}, journal = {Journal of Materials Science}, volume = {50}, number = {17}, year = {2015}, note = {

cited By 13

}, abstract = {

Abstract: The present work reports the synthesis of zinc oxide (ZnO) nanoparticles with hexagonal wurtzite structure considering a solvothermal method assisted by microwave radiation and using different solvents: water (H2O), 2-ethoxyethanol (ET) and ethylene glycol (EG). The structural characterization of the produced ZnO nanoparticles has been accessed by scanning electron microscopy, X-ray diffraction, room-temperature photoluminescence and Raman spectroscopies. Different morphologies have been obtained with the solvents tested. Both H2O and ET resulted in rods with high aspect ratio, while EG leads to flower-like structure. The UV absorption spectra showed peaks with an orange shift for synthesis with H2O and ET and blue shift for synthesis with EG. The different synthesized nanostructures were tested for photocatalyst applications, revealing that the ZnO nanoparticles produced with ET degrade faster the molecule used as model dye pollutant, i.e. methylene blue. Graphical Abstract: [Figure not available: see fulltext.] {\textcopyright} 2015 Springer Science+Business Media New York

}, doi = {10.1007/s10853-015-9125-7}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84930755181\&partnerID=40\&md5=e4f79d17244ff6df03f07f7b3ef67c56}, author = {Pimentel, A.a , Rodrigues, J.b , Duarte, P.a , Nunes, D.a , Costa, F.M.b , Monteiro, T.b , Martins, R.a , Fortunato, E.a} } @article {Dias1982307, title = {The effect of static electric and magnetic fields on the optical properties of amorphous hydrogenated silicon films produced by r.f. glow discharge}, journal = {Thin Solid Films}, volume = {89}, number = {3}, year = {1982}, note = {

cited By 1

}, pages = {307-313}, abstract = {

The aim of the present work was to study the optical properties of amorphous hydrogenated silicon films produced by capacitive and inductive r.f. glow discharge in a 3\%SiH4-Ar gas mixture. The effect of the application of static electric and magnetic fields during the film formation on the photoconductivity, photoactivation energy, recombination mechanisms and optical gap was thoroughly investigated. Films prepared in a capacitively or inductively coupled discharge show bias-dependent photoconductivities, which reach about 10-4 Ω-1 cm-1 for an inductive discharge with a negative bias and about 10-5 Ω-1 cm-1 for a capacitive discharge with a positive bias. The optical gap is of the order of 1.55 eV for capacitive films and is bias dependent for inductive films (1.45-1.85 eV). A superimposed magnetic field (of about 1 kG) increases the photoconductivity by one order of magnitude for both deposition methods. The optical gap is field dependent for inductive films (1.6-1.8 eV) and is about 1.6 eV for capacitive films. The main recombination mechanism at a moderate photon flux (less than 1014 cm-2 s-1) is monomolecular for all deposition conditions. The photoactivation energy lies between 0.1 and 0.2 eV for capacitive films and is about 0.1 eV for inductive films. It was also found that, by using suitable crossed electric and magnetic fields, it was possible to control the density and nature of the defect states in the films. These are correlated with the type of hydrogenated silicon species and with the amount of hydrogen incorporated into the films, which markedly influence the film properties. {\textcopyright} 1982.

}, doi = {10.1016/0040-6090(82)90606-X}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0019540416\&partnerID=40\&md5=cd7cdd26741f16b6501f957b8c761f38}, author = {Dias, A.G., Guimar{\~a}es, L., Martins, R.} } @article {Golshahi2013103, title = {Effect of substrate temperature on the properties of pyrolytically deposited nitrogen-doped zinc oxide thin films}, journal = {Materials Science and Engineering B: Solid-State Materials for Advanced Technology}, volume = {178}, number = {1}, year = {2013}, note = {

cited By 2

}, pages = {103-108}, abstract = {

The effect of substrate temperature (Ts) on the properties of pyrolytically deposited nitrogen (N) doped zinc oxide (ZnO) thin films was investigated. The Ts was varied from 300 {\textdegree}C to 500 {\textdegree}C, with a step of 50 {\textdegree}C. The positive sign of Hall coefficient confirmed the p-type conductivity in the films deposited at 450 {\textdegree}C and 500 {\textdegree}C. X-ray diffraction studies confirmed the ZnO structure with a dominant peak from (1 0 0) crystal plane, irrespective of the variation in Ts. The presence of N in the ZnO structure was evidenced through X-ray photoelectron spectroscopy (XPS) analysis. The obtained high N concentration reveals that the 450 {\textdegree}C is the optimal Ts. Atomic force microscope (AFM) analysis showed that the surface roughness was increased with the increasing Ts until 400 {\textdegree}C but then decreased. It is found that the transmittance of the deposited films is increased with the increasing Ts. The optical band gap calculated from the absorption edge showed that the films deposited with T s of 300 {\textdegree}C and 350 {\textdegree}C possess higher values than those deposited at higher Ts. {\textcopyright} 2012 Elsevier B.V.

}, doi = {10.1016/j.mseb.2012.10.021}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84870421478\&partnerID=40\&md5=7c8788582052842dfd83eb8d85ea56a9}, author = {Golshahi, S.a , Rozati, S.M.b , Botelho Do Rego, A.M.c , Wang, J.d , Elangovan, E.e , Martins, R.e , Fortunato, E.e} } @article {{\'A}guas2004264, title = {Effect of the discharge frequency and impedance on the structural properties of polymorphous silicon}, journal = {Thin Solid Films}, volume = {451-452}, year = {2004}, note = {

cited By 6

}, pages = {264-268}, abstract = {

This work presents a study performed on the deposition of pm-Si:H by plasma enhanced chemical vapor deposition using excitation frequencies of 13.56 and 27.12 MHz, where the interest of increasing the excitation frequency relies on higher plasma dissociation and reduced energy of ion bombardment, thus allowing the deposition of superior grade material at higher growth rates. The plasma impedance, which allows the monitoring of particle formation in the plasma, was correlated to the film properties, characterized by spectroscopic ellipsometry and hydrogen exodiffusion experiments. The set of data obtained show that by using the 27.12-MHz excitation frequency the hydrogen dilution and the r.f. power density needed to produce pm-Si:H can be reduced. Growth rates above 3.1 {\r A}/s were obtained, the films being more dense and chemically more stable than those obtained with the standard 13.56 MHz. {\textcopyright} 2003 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2003.11.020}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-1442335821\&partnerID=40\&md5=4a4324a103d5fe828367794392ca1f79}, author = {{\'A}guas, H., Raniero, L., Pereira, L., Fortunato, E., Martins, R.} } @article {{\'A}guas2004256, title = {Effect of the tunnelling oxide growth by H2O2 oxidation on the performance of a-Si:H MIS photodiodes}, journal = {Materials Science and Engineering B: Solid-State Materials for Advanced Technology}, volume = {109}, number = {1-3}, year = {2004}, note = {

cited By 0

}, pages = {256-259}, abstract = {

In this work metal-insulator-semiconductor (MIS) photodiodes with a structure: Cr/a-Si:H(n+)/a-Si:H(i)/oxide/Au were studied, where the main objective was to determine the influence of the oxide layer on the performance of the devices. The results achieved show that their performance is a function of both oxide thickness and oxide density. The a-Si:H oxidation method used was the immersion in H2O2 solution. By knowledge of the oxide growth process it was possible to fabricate photodiodes exhibiting an open circuit voltage of 0.65V and short circuit current density under AM1.5 illumination of 11mA/cm2, with a response times less than 1μs for load resistance \<400Ω, and a signal to noise ratio of 1{\texttimes}107. {\textcopyright} 2003 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.mseb.2003.10.075}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-2442436531\&partnerID=40\&md5=7d64f129f9831ec73509f357e2e402cb}, author = {{\'A}guas, H., Perreira, L., Silva, R.J.C., Fortunato, E., Martins, R.} } @article {{\'A}guas2004361, title = {Effect of the tunnelling oxide thickness and density on the performance of MIS photodiodes}, journal = {Thin Solid Films}, volume = {451-452}, year = {2004}, note = {

cited By 2

}, pages = {361-365}, abstract = {

In this work we present results of a study performed on metal-insulator-semiconductor (MIS) diodes with the following structure: substrate (glass)/Cr (2000 {\r A})/a-Si:H n+(400 {\r A})/a-Si:H i (5500 {\r A})/oxide (0-40 {\r A})/Au (100 {\r A}) to determine the influence of the oxide passivation layer grown by different techniques on the electrical performance of MIS devices. The results achieved show that the diodes with oxides grown using hydrogen peroxide present higher rectification factor (2{\texttimes}106) and signal to noise (S/N) ratio (1{\texttimes}10 7 at -1 V) than the diodes with oxides obtained by the evaporation of SiO2, or by the chemical deposition of SiO2 by plasma of hexamethyldisiloxane. However, in the case of deposited oxides, the breakdown voltage is higher, 30 V instead of 3-10 V for grown oxides. The ideal oxide thickness, determined by spectroscopic ellipsometry, is dependent on the method used to grow the oxide layer and is in the range between 6 and 20 {\r A}. The reason for this variation is related to the degree of compactation of the oxide produced, which is not relevant for applications of the diodes in the range of {\textpm}1 V, but is relevant when high breakdown voltages are required. {\textcopyright} 2003 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2003.11.013}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-1442286767\&partnerID=40\&md5=4369bf1fd2082119a011cc54950c8dae}, author = {{\'A}guas, H.a , Goullet, A.b , Pereira, L.a , Fortunato, E.a , Martins, R.a} } @article {Paula200492, title = {Effect of thermal cycling on the transformation temperature ranges of a Ni-Ti shape memory alloy}, journal = {Materials Science and Engineering A}, volume = {378}, number = {1-2 SPEC. ISS.}, year = {2004}, note = {

cited By 18

}, pages = {92-96}, abstract = {

Shape memory alloys (SMA) represents a class of metallic materials that has the capability of recovering a previously defined initial shape when subject to an adequate thermomechanical treatment. The present work aims to study the influence of thermal cycles on the transition temperatures of a Ni-Ti alloy. In this system, small variations around the equiatomic composition give rise to significant transformation temperature variations ranging from 173 to 373 K. SMA usually presents the shape memory effect after an annealing treatment at ca. 973 K. The optimisation of the thermomechanical treatment will allow to "tune" the material to different transformation temperature ranges from the same starting material, just by changing the processing conditions. Differential scanning calorimeter (DSC) and in situ high-temperature X-ray diffraction (XRD) have been used to identify the transformation temperatures and the phases that are present after different thermal cycles. The results concerning a series of thermal cycles with different heating and cooling rates (from 1.67{\texttimes}10-2 to 1.25{\texttimes}10-1 K/s) and different holding temperatures (from 473 to 1033 K) are presented. {\textcopyright} 2004 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.msea.2003.11.057}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-3042783214\&partnerID=40\&md5=f7d5d1cbc34bf3c8ecec3335ee0c27c6}, author = {Paula, A.S., Canejo, J.P.H.G., Martins, R.M.S., Braz Fernandes, F.M.} } @article {Barquinha20061756, title = {Effect of UV and visible light radiation on the electrical performances of transparent TFTs based on amorphous indium zinc oxide}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 60

}, pages = {1756-1760}, abstract = {

Insensitivity to light irradiation is desirable for conventional applications of thin-film transistors, i.e., the active matrices of displays. However, if one produces a device presenting controlled sensitivity to light, many other applications can benefit or can even be created. In this work it is shown the influence of the photon energy on the optoelectronic properties presented by n-type bottom-gate thin-film transistors based on indium zinc oxide. In the dark, the devices present very good electrical properties, working in the enhancement mode, exhibiting on-off ratios higher than 107 and channel mobility above 30 cm2/V s. Remarkable results were achieved when the devices were exposed to light radiation, the most striking one is the possibility to switch between enhancement (in the dark) and depletion (illuminated) modes, with different threshold voltages and on/off ratios, function of the light power density and wavelength used. This type of behavior permits to design circuits where one can have the same transistor working either in the enhancement or depletion modes, function of the light beam and intensity impinging on it, highly important for short wavelength detector applications. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2006.01.068}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33744792281\&partnerID=40\&md5=7ab994690f4ec6aa3562deae4ed39fea}, author = {Barquinha, P., Pimentel, A., Marques, A., Pereira, L., Martins, R., Fortunato, E.} } @article {Gokulakrishnan20111836, title = {Effects of O7+ swift heavy ion irradiation on indium oxide thin films}, journal = {Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms}, volume = {269}, number = {16}, year = {2011}, note = {

cited By 1

}, pages = {1836-1840}, abstract = {

Indium oxide thin films deposited by spray pyrolysis were irradiated by 100 MeV O7+ ions with different fluences of 5 {\texttimes} 1011, 1 {\texttimes} 1012 and 1 {\texttimes} 1013 ions/cm2. X-ray diffraction analysis confirmed the structure of indium oxide with cubic bixbyite. The strongest (2 2 2) orientation observed from the as-deposited films was shifted to (4 0 0) after irradiation. Furthermore, the intensity of the (4 0 0) orientation was decreased with increasing fluence together with an increase in (2 2 2) intensity. Films irradiated with maximum fluence exhibited an amorphous component. The mobility of the as-deposited indium oxide films was decreased from \~{}78.9 to 43.0 cm2/V s, following irradiation. Films irradiated with a fluence of 5 {\texttimes} 1011 ions/cm2 showed a better combination of electrical properties, with a resistivity of 4.57 {\texttimes} 10-3 Ω cm, carrier concentration of 2.2 {\texttimes} 1019 cm-3 and mobility of 61.0 cm2/V s. The average transmittance obtained from the as-deposited films decreased from \~{}81\% to 72\%, when irradiated with a fluence of 5 {\texttimes} 1011 ions/cm2. The surface microstructures confirmed that the irregularly shaped grains seen on the surface of the as-deposited films is modified as "radish-like" morphology when irradiated with a fluence of 5 {\texttimes} 1011 ions/cm2. {\textcopyright} 2011 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.nimb.2011.05.008}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79958022721\&partnerID=40\&md5=c47ee1bd610d33f9b306b7a6e89db394}, author = {Gokulakrishnan, V.a , Parthiban, S.a c , Elangovan, E.c , Ramamurthi, K.a , Jeganathan, K.b , Kanjilal, D.d , Asokan, K.d , Mart} } @article {Martins19871399, title = {Effects of U.V. light on the transport properties of a-Si : H films during their growth}, journal = {Journal of Non-Crystalline Solids}, volume = {97-98}, number = {PART 2}, year = {1987}, note = {

cited By 11

}, pages = {1399-1402}, abstract = {

The influence of U.V. light on the transport properties of a-Si : H films during its growth in a r.f. double chamber system was investigated by conductivity, optical absorption, I.R. absorption, spectral photoconductivity and X-ray diffraction measurements. It was concluded that the presence of U.V. light during the deposition process controls the way how hydrogen is incorporated in the structure as well as the impurity atoms. The microcrystalline films investigated present sharp peaks in the I.R. spectra. Both boron and phosphorus doped films show conductivities higher than 10 S cm-1 and estimated crystalline sizes of the order of 80 {\r A}. {\textcopyright} 1987.

}, doi = {10.1016/0022-3093(87)90335-8}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-30244551513\&partnerID=40\&md5=0d325ca98a3a6c71afa1949a8e456d8a}, author = {Martins, R.a b , Carvalho, N.a b , Fortunato, E.a b , Ma{\c c}arico, A.a b , Santos, M.a b , Baia, I.a b , Viera, M.a b , Guimar{\~a}es,} } @article {Prabakaran20082181, title = {The effects of ZnO coating on the photoluminescence properties of porous silicon for the advanced optoelectronic devices}, journal = {Journal of Non-Crystalline Solids}, volume = {354}, number = {19-25}, year = {2008}, note = {

cited By 19

}, pages = {2181-2185}, abstract = {

In the present work we investigate, the role of zinc oxide (ZnO) thin films passivating layer deposited by rf magnetron sputtering at room temperature on low (18\%) and high (80\%) porosity porous silicon (PS). The micro-Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) analysis have been carried out to understand the effect of ZnO films coating on PS. A systematic investigation from Raman spectroscopy suggests the formation of a good quality ZnO wurtzite structure on PS. The photoluminescence (PL) measurements on PS and ZnO coated PS shows a red, blue and UV emission bands at around \~{}1.8, \~{}2.78 and \~{}3.2 eV. An enhancement of all PL emission bands have been achieved after ZnO films deposition on high porosity PS. {\textcopyright} 2007 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2007.09.105}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-43049121315\&partnerID=40\&md5=530f7e0dcc48aea91aefb5175a5db88d}, author = {Prabakaran, R.a , Peres, M.b , Monteiro, T.b , Fortunato, E.a , Martins, R.a , Ferreira, I.a} } @article {Pereira200658, title = {Electrical performances of low temperature annealed hafnium oxide deposited at room temperature}, journal = {Materials Science Forum}, volume = {514-516}, number = {PART 1}, year = {2006}, note = {

cited By 1

}, pages = {58-62}, abstract = {

In this work, HfO2 was deposited by r.f. sputtering at room temperature and then annealed for different times at 200{\textdegree}C in a forming gas atmosphere. After annealing for 2 hours the HfO2 layers present a reduction on the flat band voltage of about 1 V, relatively to the as deposited film, decreasing from -2.23V down to -1.28 V. This means an improvement of the interface properties and a reduction on the oxide charge density from 1.33{\texttimes}1012 cm-2 to 7.62{\texttimes}1011 cm -2. The dielectric constant reaches a maximum of 18.3 after 5h annealing due to film{\textquoteright}s densification. When annealing for longer times such as 10h a small degradation of the electrical properties is observed. After 10h annealing the dielectric constant, flat band voltage and fixed charge density are respectively, 14.9, -2.96 V and 1.64{\texttimes}1012 cm-2 and the leakage current also increases due to film{\textquoteright}s crystallization.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-37849002518\&partnerID=40\&md5=c0d96f385d091d9e38c143f68050a038}, author = {Pereira, L., Barquinha, P., Fortunato, E., Martins, R.} } @article {Ferreira2006390, title = {Electrical properties of amorphous and nanocrystalline hydrogenated silicon films obtained by impedance spectroscopy}, journal = {Thin Solid Films}, volume = {511-512}, year = {2006}, note = {

cited By 6

}, pages = {390-393}, abstract = {

Nanocrystalline hydrogenated silicon (nc-Si:H) thin films are generally accepted to be a two phase material-Si crystalline and Si:H amorphous. This work reports the use of impedance spectroscopy to determine the amorphous and crystalline electrical conductivity of a/nc-Si:H films obtained by hot wire chemical vapour deposition. Different relaxation time or time constants are detected, if the film is composed by inhomogeneous material, by measuring ac impedance in a wide range of frequencies. Relating the conduction mechanism of the film to a series of two RC circuits constituted by a resistance and a capacitor in parallel, we may determine distinct ac conductivities and correlate that to the crystalline, amorphous and interface components. The amorphous films analysed exhibit one ac conductivity component while for nanocrystalline films two ac conductivity components are observed. The average value of ac conductivities is in agreement with that of dc conductivity. {\textcopyright} 2006.

}, doi = {10.1016/j.tsf.2005.11.100}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33747416306\&partnerID=40\&md5=5d3174bd910a487e745d72aa0872fa2d}, author = {Ferreira, I., Raniero, L., Fortunato, E., Martins, R.} } @article {Figueiredo20092143, title = {Electrical, structural and optical characterization of copper oxide thin films as a function of post annealing temperature}, journal = {Physica Status Solidi (A) Applications and Materials Science}, volume = {206}, number = {9}, year = {2009}, note = {

cited By 38

}, pages = {2143-2148}, abstract = {

Copper oxide thin films were obtained by annealing (temperature ranging between 100 and 450 {\textdegree}C) the metallic Cu films deposited on glass substrates by e-beam evaporation. XRD studies confirmed that the cubic Cu phase of the asdeposited films changes into single cubic Cu 2Ophase and single monoclinic CuO phase, depending on the annealing conditions. The crystallite size is varied betwee{\~n}12 and 31 nm. The lattice parameters of cubic Cu and Cu 2Ophases are estimated t{\~o}3.60 and ̃4.26 {\r A} , respectively. The films with Cu 2O phase showed p-type characteristics. The conductivity is decreased linearly with the decreasing temperature (1/T), which has confirmed the semiconductor nature of the deposited films. The calculated activation energy is varied between 0.10 and 0.16 eV. The surface microstructure is changed depending on the variation in the annealing temperature. The poor transmittance of the asdeposited films (\<1\%) is increased to a maximum of ̃80\% (800 nm) on annealing at 200 {\textdegree}C. The estimated direct allowed band gap is varied between 1.73 and 2.89 eV. {\textcopyright} 2009 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/pssa.200881797}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-70349137100\&partnerID=40\&md5=3e70b09aa2039ec23e719ee394630bee}, author = {Figueiredo, V.a , Elangovan, E.a , Gon{\c c}alves, G.a , Franco, N.b , Alves, E.b , Park, S.H.K.c , Martins, R.a , Fortunato, E.a} } @article {Rozati20091279, title = {Electrical, structural and optical properties of fluorine-doped zinc oxide thin films: Effect of the solution aging time}, journal = {Thin Solid Films}, volume = {518}, number = {4}, year = {2009}, note = {

cited By 27

}, pages = {1279-1282}, abstract = {

In this paper ageing effects of the solution used to prepare fluorine-doped ZnO films by the spray pyrolysis technique were investigated, concerning its role on the structure, the electrical and optical properties of films produced. The data reveal that the sheet resistance of the ZnO:F thin film decreases with the age of the solution used, reaching a minimum of 24~Ω/□, after 15~days. On the other hand the optical transmittance increases for films deposited using 6~days aging solution, decreasing afterwards as the aging time increases, being the optical transmittance in the visible range below 55\%, for films deposited from solutions 36~days in age. The X-ray diffraction spectra show that the aged films are polycrystalline in nature with a [100] predominant orientation. The data also show that the intensity of (100) peak increases as the time of solution age increases, which is related to an improvement of the film crystallinity. {\textcopyright} 2009 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2009.03.231}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-71649104709\&partnerID=40\&md5=c4561da69cb73c79f7b5ec612b74a6a8}, author = {Rozati, S.M.a , Moradi, S.a , Golshahi, S.a , Martins, R.b , Fortunato, E.b} } @article {Martins20065802, title = {Electrodeposition of polypyrrole on aluminium in aqueous tartaric solution}, journal = {Electrochimica Acta}, volume = {51}, number = {26}, year = {2006}, note = {

cited By 29

}, pages = {5802-5810}, abstract = {

The electrosynthesis of polypyrrole (PPy) has been achieved on aluminium in aqueous medium of tartaric acid by means of cyclic voltammetry, potentiostatic and galvanostatic techniques. Scanning electron microscopy (SEM) and X-ray microanalysis by energy spectroscopy dispersion (EDS) applying on surfaces show that the PPy coating is developed from the metal surface through the cracks of the initial Al2O3 layer. A mechanism involving the participation of the supporting electrolyte and the pyrrole (Py) in distinct active sites was proposed based on the linear sweep voltammetry. It is observed for all applied electrochemical techniques that the pyrrole concentration has to be higher than 0.1 M to allow the polypyrrole electrodeposition in acid medium. Scanning electron microscopy, secondary electrons (SE) and backscattering electrons (BE), shows that the PPy coating obtained in galvanostatic and potentiostatic modes starts with small islands at weak applied potentials or current densities. Moreover, EDS reveals a good homogeneity and compactness of the film achieved in galvanostatic method. The corrosion results in 3\% NaCl medium show that the PPy coating decreases the corrosion behaviour of the aluminium. The bilayer Al2O3/PPy shows a capacitor with future applications. {\textcopyright} 2006 Elsevier Ltd. All rights reserved.

}, doi = {10.1016/j.electacta.2006.03.015}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33746651716\&partnerID=40\&md5=ecf58b46a978d68f65179cb796215ca4}, author = {Martins, J.I.a , Costa, S.C.a , Bazzaoui, M.a , Gon{\c c}alves, G.b , Fortunato, E.b , Martins, R.b} } @article {Lavado1989791, title = {Electron paramagnetic resonance of defects in doped microcrystalline silicon}, journal = {Vacuum}, volume = {39}, number = {7-8}, year = {1989}, note = {

cited By 0

}, pages = {791-794}, abstract = {

Experimental results on structure defects in microcrystalline (μc) n- and p-doped μc-S1-x:Cx:H films deposited on alkali-free glass substrates by spatial plasma separation1 and obtained by electron paramagnetic resonance (EPR) are presented. The technique used for subtracting the substrate effect on recorded spectra is also discussed as well as its quantification. The microscopic structure of intrinsic defects and impurity states and their role in transport mechanisms are studied and correlated with the composition of their films. These results are also related to transport properties of deposited films in order to observe the role of dopant centres, located at conduction band tails, in controlling the electrical properties. {\textcopyright} 1989.

}, doi = {10.1016/0042-207X(89)90039-0}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024876089\&partnerID=40\&md5=e21bef0d3b3614a3c1fd831127592d76}, author = {Lavado, M., Martins, R., Ferreira, I., Lavareda, G., Fortunato, E., Vieira, M., Guimar{\~a}es, L.} } @article {Martins20061471, title = {Electron transport and optical characteristics in amorphous indium zinc oxide films}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 54

}, pages = {1471-1474}, abstract = {

This paper discusses the electron transport and the optical characteristics of amorphous indium zinc oxide and the role of the oxygen partial pressure on tailoring its properties. The data show that by varying the oxygen partial pressure during the deposition process from 10-3 to 2 {\texttimes} 10-1 Pa, the electrical resistivity varies from about 10-4 to 2 {\texttimes} 101 Ω cm, which corresponds to a variation on the Hall mobility from 60 to 10 cm2 V-1 s-1. The conductivity and mobility analysis show that the transport of carriers is not band tail limited, as happens in conventional disordered semiconductors, but highly dependent on the ionicity and the presence of oxygen vacancies, where mobility is mainly limited by carrier scattering. The optical characteristics inferred from the transmittance data reveal films with optical gaps in the range of 3.68-3.76 eV, very close to the ones observed on crystalline/polycrystalline IZO films (3.7-3.9 eV). {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2006.02.009}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33745459468\&partnerID=40\&md5=23c7ea83382eaed491fb43a496086622}, author = {Martins, R.a , Almeida, P.b , Barquinha, P.a , Pereira, L.a , Pimentel, A.a , Ferreira, I.a , Fortunato, E.a} } @article {Martins20081322, title = {Electron transport in single and multicomponent n-type oxide semiconductors}, journal = {Thin Solid Films}, volume = {516}, number = {7}, year = {2008}, note = {

cited By 19

}, pages = {1322-1325}, abstract = {

The electron transport in n-type polycrystalline zinc oxide, nanocrystalline Zinc-Gallium-Oxygen and amorphous Indium-Zinc-Oxygen systems produced by rf magnetron sputtering at room temperature, under different oxygen partial pressure were investigated. It was found that the carrier transport is not band tail limited, being governed by metal cations irrespective to the film{\textquoteright}s structure. The highest net room temperature electron mobility was achieved on the amorphous films and noticed that for the single component oxides the mobility decreases as the carrier concentration increases, while the reverse behaviour was observed for the multicomponent oxides, independently of their structure. These behaviours are related to the role that negative charge defects in excess of 1010~cm- 2 generated on multicomponent oxides have on carriers scattering and so on their electronic performances. {\textcopyright} 2007 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2007.03.158}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-38749094149\&partnerID=40\&md5=c395fc7f34261df3d4349d6df9db29b4}, author = {Martins, R.a , Barquinha, P.a , Pimentel, A.a , Pereira, L.a , Fortunato, E.a , Kang, D.b , Song, I.b , Kim, C.b , Park, J.b , P} } @article {Jones1979147, title = {Electronic transport and photoconductivity in phosphorus-doped amorphous germanium}, journal = {Philosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties}, volume = {39}, number = {2}, year = {1979}, note = {

cited By 19

}, pages = {147-158}, abstract = {

It is shown that the electronic properties of amorphous germanium (a-Ge) prepared by the glow-discharge decomposition of germane can be controlled systematically by substitutional phosphorus doping from the gas phase. Specimens with different doping levels have{\textquoteright} been investigated by conductivity, thermoelectric power and Hall effect measurements in a temperature range between 160 and 450 K. The dependence of conductivity on doping level is qualitatively similar to that in a-Si, but the range of control is limited in a-Ge by the smaller mobility gap. Also the larger overall density of gap states in this material reduces the doping sensitivity. The above transport measurements and their temperature dependence can be interpreted in a quantitatively consistent manner- by a two-path model in which conduction takes place in the extended states and in another path through the localized states. As 111 a-Si, the photoconductivity of glow-discharge Ge can be appreciably sensitized by phosphorus doping. The μτ product deduced from such experiments on a-Ge and a-Si are compared for different preparation techniques. The data show that irrespective of the presence of hydrogen the method of deposition remains an important factor in determining the density of gap states. {\textcopyright} 1979 Taylor \& Francis Ltd.

}, doi = {10.1080/13642817908246344}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0018434917\&partnerID=40\&md5=b750172eaf0a6461357002a20eab9fcd}, author = {Jones, D.I.a , Spear, W.E.a , Le Comber, P.G.a , Li, S.a , Martins, R.a b} } @article {Elamurugu2012, title = {The electronic transport mechanism in indium molybdenum oxide thin films RF sputtered at room temperature}, journal = {EPL}, volume = {97}, number = {3}, year = {2012}, note = {

cited By 2

}, abstract = {

Indium molybdenum oxide (IMO) thin films were radio-frequency (RF) sputtered at room temperature (RT) and studied as a function of base pressure (BP). The crystallinity of the films is decreased with the increase in BP. A maximum mobility (μ) of 49.6 cm 2 V -1 s -1 was obtained from the IMO films deposited at RT without any post-annealing treatment. The electronic behaviour of the deposited films was investigated by temperature-dependent (100-550 K) Hall measurements. Study on the scattering mechanisms based on the experimental data and theoretical models show that the ionized scattering centres are dominating. The films possess wide work function (4.91 eV) and high transmittance (\> 70\%) over visible and near infrared (NIR) range. The obtained results, especially the high work function and NIR transmittance, are very promising particularly in applications such as optical detectors and solar cells. Copyright {\textcopyright} EPLA, 2012.

}, doi = {10.1209/0295-5075/97/36002}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84857067788\&partnerID=40\&md5=1fedea4fee510e8936e09a074ba81654}, author = {Elamurugu, E.a , Shanmugam, P.a , Gon{\c c}alves, G.a , Franco, N.b , Alves, E.b , Martins, R.a , Fortunato, E.a} } @article {Martins2011332, title = {Electronics with and on paper}, journal = {Physica Status Solidi - Rapid Research Letters}, volume = {5}, number = {9}, year = {2011}, note = {

cited By 36

}, pages = {332-335}, abstract = {

Today there is a strong interest in the scientific and industrial community concerning the use of biopolymers for electronic applications, driven mainly by low-cost and disposable applications. Adding to this interest, we must recognise the importance of the dream of wireless auto-sustained and low-energy-consumption electronics. This dream can be fulfilled by cellulose paper, the lightest and the cheapest known substrate material, as well as the Earth{\textquoteright}s major biopolymer and of tremendous global economic importance. Most of the paper used up to now is optimised in terms of the required mechanical and physical properties to be used as the support of inks of different origins. In the future, specific electronic heterogeneous paper sheets should be fabricated aiming to get paper fibers with required bulk and surface functionalities, proper water/vapour barrier, size and diameter/thickness of the fibrils and full paper thickness. This will be the function of components/devices to be incorporated/integrated such as thin-film transistors, complementary metal oxide semiconductor devices, passive electronic components (resistances, inductors and capacitors), memory transistors, electrochromics and thin-film paper batteries. {\textcopyright} 2011 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/pssr.201105247}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-80052299822\&partnerID=40\&md5=609318cb12d92930058d7d0730576f12}, author = {Martins, R., Ferreira, I., Fortunato, E.} } @article {Gaspar20151421, title = {Engineered cellulose fibers as dielectric for oxide field effect transistors}, journal = {Physica Status Solidi (C) Current Topics in Solid State Physics}, volume = {12}, number = {12}, year = {2015}, note = {

cited By 0

}, pages = {1421-1426}, abstract = {

When thinking on low cost and sustainable electronic systems, paper can be considered as an interesting option to be used as substrate but also as a component of such systems. In this work we have tailored paper samples that were used simultaneously as physical support and dielectric in oxide based paper field effect transistors (FETs). It was observed that the gate leakage current in these devices depends directly from fibril{\textquoteright}s dimension and arrangement, being lower for micro/nano fibrillated cellulose paper. Moreover, extra ionic charge added to the paper during its production results in the improvement of FETs{\textquoteright} electrical properties, with saturation mobility of 16 cm 2V -1s -1 and on/off current ratio close to 105. {\textcopyright} 2015 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/pssc.201510163}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84950239080\&partnerID=40\&md5=d100837b778ff72dd8dde4fb8a042d10}, author = {Gaspar, D.a , Pereira, L.a , Delattre, A.b , Guerin, D.b , Fortunato, E.a , Martins, R.a} } @article {Martins200239, title = {Engineering of a-Si:H device stability by suitable design of interfaces}, journal = {Solar Energy Materials and Solar Cells}, volume = {73}, number = {1}, year = {2002}, note = {

cited By 4

}, pages = {39-49}, abstract = {

Where a-Si:H pin devices are concerned, one of the main obstacles regarding improved performance is device stability, usually attributed to adverse behaviour at various interfaces within the device. Several attempts have been made to overcome this problem, such as the use of blocking layers at the interfaces. Although these have led to some improvements in device performance, most of the problems associated with device stability remain. This is mainly due to the defects at the interfaces, since the blocking layers (silicon alloys with carbon, nitrogen or oxygen) usually have a high density of bulk states, in comparison to intrinsic a-Si:H films. In this paper, we present a method that seems to be capable of improving device stability. It consists of performing a controlled removal of oxide interlayers at the interfaces, by an appropriate etching process. This enables the production of highly smoothed interfaces, and reduces possible cross-contamination of the i-layer from the adjacent doped layers. This amounts to a new design of typical pin devices, in which thin absorber layers are placed at the p/i and i/n interfaces. Their purpose is to trap most of the impurity atoms diffused from the doped layers, after which they are removed by appropriate etching. The fabrication of the absorbers (sacrificial layers), the nature of the etching and the tailoring of the defect profile at the interfaces will be discussed, including the performance exhibited by the resulting devices. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0927-0248(01)00109-X}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036568574\&partnerID=40\&md5=5296f60b545f29ac23a5ccde5b5433d9}, author = {Martins, R., Ferreira, I., {\'A}guas, H., Silva, V., Fortunato, E., Guimar{\~a}es, L.} } @article {Martins1991757, title = {Engineering of plasma deposition systems used for producing large area a-Si:H devices}, journal = {Journal of Non-Crystalline Solids}, volume = {137-138}, number = {PART 2}, year = {1991}, note = {

cited By 9

}, pages = {757-760}, abstract = {

One of the main problems in producing large area amorphous silicon devices concerns films uniformity. In this paper we present data concerning the role of reactor geometry and design and on the film performances as well as the problems related to mechanical mismatches in scaling up the reactor size. {\textcopyright} 1991 Elsevier Science Publishers B.V. All rights reserved.

}, doi = {10.1016/S0022-3093(05)80231-5}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0040387195\&partnerID=40\&md5=5010491146db49d438d74afee9504a89}, author = {Martins, R., Ferreira, I., Carvalho, N., Guimar{\~a}es, L.} } @article {Martins19941107, title = {Engineering of the energy coupling in PECVD systems used to produce large area a-Si:H coatings}, journal = {Vacuum}, volume = {45}, number = {10-11}, year = {1994}, note = {

cited By 4

}, pages = {1107-1108}, abstract = {

This paper deals with the engineering aspects related to the rf energy coupling in Plasma Enhanced Chemical Vapour Deposition (PECVD) processes, in a diode-type unit in which an extra grid is used. The main emphasis is given in the determination of the real power delivered to the gas and comparing it with the total power losses, besides determining the best way to control the powder formed during the process. {\textcopyright} 1994.

}, doi = {10.1016/0042-207X(94)90036-1}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028516123\&partnerID=40\&md5=ab7ab4e1a4c91f0b1e5d442a8dd310f5}, author = {Martins, R., Ferreira, I.} } @article {Nayak2011640, title = {Environmental, optical, and electrical stability study of solution-processed zinc-tin-oxide thin-film transistors}, journal = {IEEE/OSA Journal of Display Technology}, volume = {7}, number = {12}, year = {2011}, note = {

cited By 15

}, pages = {640-643}, abstract = {

In this paper, we report the environmental, optical, and gate bias stress stability of amorphous zinc-tin-oxide (ZTO) thin-film transistors (TFTs) fabricated by sol-gel spin-coating method. The ZTO TFTs showed excellent environmental and optical stability. The threshold voltage stability of ZTO TFTs was sensitive to both positive and negative gate bias stress. Maximum threshold voltage shifting of +1.9 and -3.2 V was observed under a gate bias stress of +10 and -10 V, respectively, with no significant change to subthreshold swing value. {\textcopyright} 2006 IEEE.

}, doi = {10.1109/JDT.2011.2160151}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-80054898938\&partnerID=40\&md5=8c0722c32ec4f143d58b08ed793d6834}, author = {Nayak, P.K., Pinto, J.V., Gon{\c c}alves, G., Martins, R., Fortunato, E.} } @article {Fortunato2010, title = {Erratum: Thin-film transistors based on p-type Cu2 O thin films produced at room temperature (Applied Physics Letters (2010) 96 (192102))}, journal = {Applied Physics Letters}, volume = {96}, number = {23}, year = {2010}, note = {

cited By 5

}, abstract = {n/a}, doi = {10.1063/1.3449139}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77953522404\&partnerID=40\&md5=8b823bc85187c7425ef210bb9a080d38}, author = {Fortunato, E.a , Figueiredo, V.a , Barquinha, P.a , Elamurugu, E.a , Barros, R.a b , Gonalves, G.a , Park, S.-H.K.a , Hwang, C.-} } @article {Ferreira2004236, title = {Ethanol vapour detector based in porous a-Si:H films produced by HW-CVD technique}, journal = {Sensors and Actuators, B: Chemical}, volume = {100}, number = {1-2}, year = {2004}, note = {

cited By 2

}, pages = {236-239}, abstract = {

In this work, we show the possibility to use undoped porous silicon (PS) thin films produced by hot wire chemical vapour deposition technique (HW-CVD) as ethanol detector. Silicon thins films produced by HW-CVD technique, under certain deposition conditions, have a porous structure [Vacuum 52 (1999) 147]. Therefore, in the presence of an alcohol, the OH group is adsorbed by the uncompensated bonds behaving as donor-like carriers leading to an increase in the current flowing through the material. This current enhancement is bias dependent in glass/ITO/i-a-Si:H/Al sensor and increases as the ethanol vapour pressure increases from 10-1mbar to atmospheric pressure. The response time of the current of the sensor and its recovery time are in the range of 10-50s at room temperature. Ethanol quantities above 50ppm can be detected. {\textcopyright} Published by Elsevier B.V.

}, doi = {10.1016/j.snb.2004.01.008}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-2342584734\&partnerID=40\&md5=c2c9ae6f1f9054e30b218b7c79ce519e}, author = {Ferreira, I., Fortunato, E., Martins, R.} } @article {Grimmeiss200456, title = {Excellence in European universities}, journal = {Materials Today}, volume = {7}, number = {12}, year = {2004}, note = {

cited By 0

}, pages = {56-60}, abstract = {

The need to improve the efficiency of the European university system is discussed. It is considered possible to increase university funding by letting students pay for their education. It is suggested that European universities raise more money for research from private sources by selling services. It is found appropriate to strive for excellence at the level of specific departments or schools to begin with.

}, doi = {10.1016/S1369-7021(04)00572-3}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-9544229712\&partnerID=40\&md5=ab05336d644dde7df3727fa4445b38c2}, author = {Grimmeiss, H.a , Martins, R.b , Duart, J.M.M.c} } @article {Pinto2013729, title = {Extended-gate ISFETs based on sputtered amorphous oxides}, journal = {IEEE/OSA Journal of Display Technology}, volume = {9}, number = {9}, year = {2013}, note = {

cited By 4

}, pages = {729-734}, abstract = {

We present the results obtained with an extended-gate ISFET totally based on amorphous oxides (GIZO as the semiconductor, +{\hbox{Ta}}-{2}{\hbox{O}}-{5}{\ hbox{:SiO}}-inf2-inf as the dielectric and +{\hbox{Ta}}-{2}{\hbox{O}}-inf5-inf as the sensitive layer). A full characterization of the device was performed with constant ionic strength pH buffer solutions, revealing a sensitivity of 40 mV/pH with small hysteresis, and good linearity in the pH 4-pH 10 range buffer solutions. These results clearly show that it is possible to produce room-temperature disposable and low cost bio-sensors. {\textcopyright} 2005-2012 IEEE.

}, doi = {10.1109/JDT.2012.2227298}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84883791426\&partnerID=40\&md5=cfc43e3f3d3d58040e9fa29f8360c13a}, author = {Pinto, J.V.a , Branquinho, R.a , Barquinha, P.a , Alves, E.b , Martins, R.a , Fortunato, E.a} } @article {Prabakaran20082892, title = {Fabrication and characterization of hybrid solar cells based on copper phthalocyanine/porous silicon}, journal = {Journal of Non-Crystalline Solids}, volume = {354}, number = {19-25}, year = {2008}, note = {

cited By 15

}, pages = {2892-2896}, abstract = {

This work refers to the fabrication of hybrid solar cells based on porous silicon (PS) filled with copper phthalocyanine (CuPc) to form GZO/CuPc-PS/Si/Al structure. We used n-type Si since photoinduced charge transfer from CuPc to Si is observed only for n-type Si. The characteristic 100\% peak at 6.8{\textdegree}2θ from XRD confirms that the CuPc coating on PS exists in α-CuPc polymorph. The systematic increase in FWHM of XRD peak at 69.1{\textdegree}2θ and red-shift of LO phonon Raman spectra indicate a progressive reduction of Si nanocrystallites size with increasing etching time and the estimated size agrees well with atomic force microscopic images. The FTIR results confirm the formation of α-CuPc polymorph and it is also corroborated well with XRD and Raman results. {\textcopyright} 2008.

}, doi = {10.1016/j.jnoncrysol.2007.10.096}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-43049120953\&partnerID=40\&md5=7a2b7361df0fa6e45de6b570b347b9f8}, author = {Prabakaran, R., Fortunato, E., Martins, R., Ferreira, I.} } @article {{\'A}guas2001319, title = {Fast and cheap method to qualitatively measure the thickness and uniformity of ZrO2 thin films}, journal = {Materials Science in Semiconductor Processing}, volume = {4}, number = {1-3}, year = {2001}, note = {

cited By 3

}, pages = {319-321}, abstract = {

This work presents a fast method to determine qualitatively the uniformity and the thickness of transparent or semitransparent thin films in the visible to near-infrared region. The method proposed is based on the information recorded by a colour scanner in the form of coloured regions, due to the constructive interferences caused by multibeam wavelength light sources as function of the film thickness and refractive index. The method is well applied in transparent films, where the uniformity cannot be seen by visual inspection. This paper shows that the results obtained for ZrO2 films are satisfactory enabling the application of this technique to determine the films uniformity in fast and cheap way.

}, doi = {10.1016/S1369-8001(00)00106-2}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035247528\&partnerID=40\&md5=888b5a07c4383280564bf2aec1aa2599}, author = {{\'A}guas, H., Marques, A., Martins, R., Fortunato, E.} } @article {Fortunato20051281, title = {Flexible a-Si: H position-sensitive detectors}, journal = {Proceedings of the IEEE}, volume = {93}, number = {7}, year = {2005}, note = {

cited By 26

}, pages = {1281-1286}, abstract = {

Flexible and large area (5 mm {\texttimes} 80 mm with an active length of 70 mm) position-sensitive detectors (PSDs) deposited onto polymeric substrates (polyimide - Kapton VN) have been fabricated. The optimized structure presented is based on a heterojunction of amorphous silicon (a-Si: H)/ZnO: Al. The sensors were characterized by spectral response, photocurrent dependence as a function of light intensity, and position detection measurements. The set of data obtained on one-dimensional PSDs based on the heterojunction show excellent performances with a maximum spectral response of 0.12 A/W at 500 nm and a nonlinearity of {\textpm}10\% over 70-mm length. The produced sensors present a nonlinearity higher than those ones produced on glass substrates, due to the different thermal coefficients exhibited by the polymer and the a-Si: H film. In order to prove this behavior, it was measured the defect density obtained by the constant photocurrent method on a-Si: H thin films deposited on polymeric substrates and bent with different radii of curvature. {\textcopyright} 2005 IEEE.

}, doi = {10.1109/JPROC.2005.850302}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-23244464424\&partnerID=40\&md5=0d858a2db73c058c564087f329d14db5}, author = {Fortunato, E.a b , Pereira, L.a , {\'A}guas, H.a c d , Ferreira, I.a , Martins, R.a e} } @article {Barquinha2015, title = {Flexible and Transparent WO3 Transistor with Electrical and Optical Modulation}, journal = {Advanced Electronic Materials}, volume = {1}, number = {5}, year = {2015}, note = {

cited By 3

}, abstract = {n/a}, doi = {10.1002/aelm.201500030}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962082331\&partnerID=40\&md5=e151873fb0ec32a127e6f30e0874f580}, author = {Barquinha, P., Pereira, S., Pereira, L., Wojcik, P., Grey, P., Martins, R., Fortunato, E.} } @article {Fortunato2000182, title = {Flexible large area thin film position sensitive detectors}, journal = {Sensors and Actuators, A: Physical}, volume = {86}, number = {3}, year = {2000}, note = {

cited By 12

}, pages = {182-186}, abstract = {

Large area thin film position sensitive detectors based on amorphous silicon technology have been prepared on polyimide substrates using the conventional plasma-enhanced chemical vapour deposition. The sensors have been characterized by spectral response, light intensity dependence and linearity measurements in a bent state in order to evaluate the properties in real working conditions. The obtained one-dimensional (1D) position sensors with 10 mm width and 20 mm length present a non-linearity of {\textpm}1\% which are comparable to the ones produced on glass substrates.

}, doi = {10.1016/S0924-4247(00)00446-5}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034324733\&partnerID=40\&md5=a696e2bf05cc432cee51cedeba014e05}, author = {Fortunato, E., Ferreira, I., Giuliani, F., Martins, R.} } @article {Fortunato2004119, title = {Flexible position sensitive photodetectors based on a-Si:H heterostructures}, journal = {Sensors and Actuators, A: Physical}, volume = {116}, number = {1}, year = {2004}, note = {

cited By 5

}, pages = {119-124}, abstract = {

This work describes the fabrication and characterization of an improved version of large area (5mm{\texttimes}80mm with an active length of 70mm) flexible position sensitive detectors deposited onto polymeric substrates (polyimide-Kapton{\textregistered} VN). The new configuration presented by the sensor is based on a heterostructure of a-Si:H/ZnO:Al. The sensors were characterized by spectral response, photocurrent dependence as a function of light intensity and position detection measurements. The set of data obtained on one-dimensional position sensitive detectors based on the heterostructure show excellent performances with a maximum spectral response of 0.12A/W at 500nm and a non-linearity of {\textpm}10\% over 70mm length. The produced sensors present a non-linearity higher than those ones produced on glass substrates, due to the different thermal coefficients exhibited by the polymer and the amorphous silicon film. In order to prove this behaviour, it was measured the defect density obtained by the constant photocurrent method on amorphous silicon deposited on polymeric substrates bended with different radius of curvature. {\textcopyright} 2004 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.sna.2004.01.065}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-4444332760\&partnerID=40\&md5=a3604ed8b01a35e3a8a3822575f26232}, author = {Fortunato, E., Pereira, L., {\'A}guas, H., Ferrira, I., Martins, R.} } @article {Fortunato2013687, title = {Foreword}, journal = {IEEE/OSA Journal of Display Technology}, volume = {9}, number = {9}, year = {2013}, note = {

cited By 0

}, pages = {687}, abstract = {n/a}, doi = {10.1109/JDT.2013.2278778}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84884839417\&partnerID=40\&md5=2e8925c77567a895cd3030b0ae9a7439}, author = {Fortunato, N.a , Jang, J.b , Barquinha, P.a , Nathan, A.c , Martins, R.a} } @article {Madan20092431, title = {From materials science to applications of amorphous, microcrystalline and nanocrystalline silicon and other semiconductors}, journal = {Philosophical Magazine}, volume = {89}, number = {28-30}, year = {2009}, note = {

cited By 3

}, pages = {2431-2434}, abstract = {

The special Professor Walter E. Spear commemoration issue of the Philosophical Magazine, published in October 2009, contains papers which cover the numerous relevant issues, driven by commercial applications, primarily solar energy and displays. Kocka reviews the complex microstructure of crystallites embedded in the amorphous silicon tissue, the transport mechanism is determined by the conductive grains and influenced by the passivation through H at the grain boundaries. Hugger and co-researchers report on transient photocapacitance spectroscopy and drive-level capacitance profiling as a way of elucidating the fundamental electronic properties of hydrogenated ncSi. Tawada recounts the history of a-Si:H pin heterojunction solar cells, emphasizing the role of the p-type silicon carbide layer in the improvement of the device. Schubert and colleagues focus their work on the production of flexible PV modules with many applications in the architectural arena or integrated into clothing.

}, doi = {10.1080/14786430903168763}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77649133106\&partnerID=40\&md5=4855e89e4161f1a3949f0016ae250966}, author = {Madan, A.a , Martins, R.b} } @article {Ferreira2003225, title = {From porous to compact films by changing the onset conditions of HW-CVD process}, journal = {Thin Solid Films}, volume = {427}, number = {1-2}, year = {2003}, note = {

cited By 5

}, pages = {225-230}, abstract = {

Doped a/μc-Si:H films were produced in different starting deposition conditions by the hot wire chemical vapor deposition technique. In this paper, we show that by changing the initial onset deposition conditions of the process and maintaining the overall pressure, hydrogen dilution and filament temperature, it is possible to control the compactness of the films. As the films nucleation is the key parameter to produce compact films, we show that starting the process with hydrogen and progressively introducing the process gas enhances the compactness and improve the electrical properties of the films produced. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0040-6090(02)01186-0}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037416674\&partnerID=40\&md5=157c8b71027af4e4af840998ed0f005f}, author = {Ferreira, I.a , Costa, M.E.V.b , Fortunato, E.a , Martins, R.a} } @article {Fortunato2005590, title = {Fully transparent ZnO thin-film transistor produced at room temperature}, journal = {Advanced Materials}, volume = {17}, number = {5}, year = {2005}, note = {

cited By 677

}, pages = {590-594}, abstract = {

The possibility of fabricating high-mobility ZnO thin-film transistors (ZnO-TFT) at room temperature by rf magnetron sputtering was discussed. It was found that the films were nanocrystalline with a hexagonal structure and exhibited a preferred orientation with the c-axis perpendicular to the substrate. The undoped ZnO films exhibited improved crystallinity fraction of the nanocrystals and low oxygen vacancies. Analysis shows that the exposure of the ZnO-TFTs to the ambient light has no effect on the current voltage characteristics.

}, doi = {10.1002/adma.200400368}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-16244382410\&partnerID=40\&md5=4c5788447641ea95cbf1cc7a32b9f75f}, author = {Fortunato, E.M.C., Barquinha, P.M.C., Pimentel, A.C.M.B.G., Gon{\c c}alves, A.M.F., Marques, A.J.S., Pereira, L.M.N., Martins, R.F.P.} } @article {Barquinha2008954, title = {Gallium-indium-zinc-oxide-based thin-film transistors: Influence of the source/drain material}, journal = {IEEE Transactions on Electron Devices}, volume = {55}, number = {4}, year = {2008}, note = {

cited By 126

}, pages = {954-960}, abstract = {

During the last years, oxide semiconductors have shown that they will have a key role in the future of electronics. In fact, several research groups have already presented working devices with remarkable electrical and optical properties based on these materials, mainly thin-film transistors (TFTs). Most of these TFTs use indium-tin oxide (ITO) as the material for source/drain electrodes. This paper focuses on the investigation of different materials to replace ITO in inverted-staggered TFTs based on gallium-indium-zinc oxide (GIZO) semiconductor. The analyzed electrode materials were indium-zinc oxide, Ti, Al, Mo, and Ti/Au, with each of these materials used in two different kinds of devices: one was annealed after GIZO channel deposition but prior to source/drain deposition, and the other was annealed at the end of device production. The results show an improvement on the electrical properties when the annealing is performed at the end (for instance, with Ti/Au electrodes, mobility rises from 19 to 25 cm2/V {\textperiodcentered} s, and turn-on voltage drops from 4 to 2 V). Using time-of-flight secondary ion mass spectrometry (TOF-SIMS), we could confirm that some diffusion exists in the source/drain electrodes/ semiconductor interface, which is in close agreement with the obtained electrical properties. In addition to TOF-SIMS results for relevant elements, electrical characterization is presented for each kind of device, including the extraction of source/drain series resistances and TFT intrinsic parameters, such as VTi (intrinsic threshold voltage). {\textcopyright} 2008 IEEE.

}, doi = {10.1109/TED.2008.916717}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-41949130354\&partnerID=40\&md5=bf93ebcc48cde566574e93e29c898eba}, author = {Barquinha, P.a , Vila, A.M.b , Gon{\c c}alves, G.a , Pereira, L.a , Martins, R.a , Morante, J.R.b , Fortunato, E.a} } @article {Lopes2009, title = {Gate-bias stress in amorphous oxide semiconductors thin-film transistors}, journal = {Applied Physics Letters}, volume = {95}, number = {6}, year = {2009}, note = {

cited By 116

}, abstract = {

A quantitative study of the dynamics of threshold-voltage shifts with time in gallium-indium zinc oxide amorphous thin-film transistors is presented using standard analysis based on the stretched exponential relaxation. For devices using thermal silicon oxide as gate dielectric, the relaxation time is 3{\texttimes} 105 s at room temperature with activation energy of 0.68 eV. These transistors approach the stability of the amorphous silicon transistors. The threshold voltage shift is faster after water vapor exposure suggesting that the origin of this instability is charge trapping at residual-water-related trap sites. {\textcopyright} 2009 American Institute of Physics.

}, doi = {10.1063/1.3187532}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-69049119241\&partnerID=40\&md5=fc7564312a4461ffe4b0cf4d965cd130}, author = {Lopes, M.E.a , Gomes, H.L.a , Medeiros, M.C.R.a , Barquinha, P.b , Pereira, L.b , Fortunato, E.b , Martins, R.b , Ferreira, I.b} } @article {Alves20131483, title = {GelatinnZn(CF3SO3)2 polymer electrolytes for electrochromic devices}, journal = {Electroanalysis}, volume = {25}, number = {6}, year = {2013}, note = {

cited By 7

}, pages = {1483-1490}, abstract = {

The present work is focused on gelatin-based electrolytes doped with a range of concentration of zinc triflate (Zn(CF3SO3)2). The transparent-thin-film samples have been represented by the notation GelatinnZn(CF3SO3)2, where n represents the zinc triflate salt concentration in the electrolyte membranes from 0.00 wt\% to 10.93 wt\% The samples have been characterized by conductivity measurements, thermal analysis, cyclic voltammetry, X-ray diffraction (XRD), polarized optical microscopy (POM) and scanning electron microscopy (SEM). The gelatin-based electrolytes were also tested as ionic conductors in electrochromic devices with the glass/ITO/WO3/gelatin-based electrolyte/CeO2-TiO2/ITO/glass configuration. {\textcopyright} 2013 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/elan.201300038}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84879010591\&partnerID=40\&md5=9773d4607a4304767681670f84980929}, author = {Alves, R.D.a , Rodrigues, L.C.a , Andrade, J.R.b , Fernandes, M.c , Pinto, J.V.d , Pereira, L.d , Pawlicka, A.b , Martins, R.d ,} } @article {Veigas20124802, title = {Gold on paper-paper platform for Au-nanoprobe TB detection}, journal = {Lab on a Chip - Miniaturisation for Chemistry and Biology}, volume = {12}, number = {22}, year = {2012}, note = {

cited By 56

}, pages = {4802-4808}, abstract = {

Tuberculosis (TB) remains one of the most serious infectious diseases in the world and the rate of new cases continues to increase. The development of cheap and simple methodologies capable of identifying TB causing agents belonging to the Mycobacterium tuberculosis Complex (MTBC), at point-of-need, in particular in resource-poor countries where the main TB epidemics are observed, is of paramount relevance for the timely and effective diagnosis and management of patients. TB molecular diagnostics, aimed at reducing the time of laboratory diagnostics from weeks to days, still require specialised technical personnel and labour intensive methods. Recent nanotechnology-based systems have been proposed to circumvent these limitations. Here, we report on a paper-based platform capable of integrating a previously developed Au-nanoprobe based MTBC detection assay - we call it "Gold on Paper". The Au-nanoprobe assay is processed and developed on a wax-printed microplate paper platform, allowing unequivocal identification of MTBC members and can be performed without specialised laboratory equipment. Upon integration of this Au-nanoprobe colorimetric assay onto the 384-microplate, differential colour scrutiny may be captured and analysed with a generic "smartphone" device. This strategy uses the mobile device to digitalise the intensity of the colour associated with each colorimetric assay, perform a Red Green Blue (RGB) analysis and transfer relevant information to an off-site lab, thus allowing for efficient diagnostics. Integration of the GPS location metadata of every test image may add a new dimension of information, allowing for real-time epidemiologic data on MTBC identification. {\textcopyright} 2012 The Royal Society of Chemistry.

}, doi = {10.1039/c2lc40739f}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84867560012\&partnerID=40\&md5=2b440b1a3c350ed2a7dfd7de86bfd6d2}, author = {Veigas, B.a b , Jacob, J.M.b , Costa, M.N.b , Santos, D.S.b , Viveiros, M.c , In{\'a}cio, J.d , Martins, R.b , Barquinha, P.b , Fort} } @article {Martins2002603, title = {Growth model of gas species produced by the hot-wire and hot-wire plasma-assisted techniques}, journal = {Key Engineering Materials}, volume = {230-232}, year = {2002}, note = {

cited By 0

}, pages = {603-606}, abstract = {

The model presented is based on the heat transfer and energy balance equations that rule the set of physical and chemical interactions that take place on the gas phase of a growth process, assuming that the deposition process occurs under laminar dynamic flow conditions (Knudsen number below 1). In these conditions, the chemistry and physics of the process involved in the growth mechanism of silicon thin films produced by the hot wire or the hot-wire plasma assisted technique can be proper derived by balance equations that supply information about how the plasma density, the gas dilution and the gas temperature influence the growth mechanism and the equilibrium of the concentration of species presented on the growth surface. The model developed establishes a relation between the abundance species formed and the parameters initiators of the process such as the filament temperature and the rf power density used.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036432239\&partnerID=40\&md5=e9d3ce02bbdf0470ffc3c29abf691a0f}, author = {Martins, R., Ferreira, I., Fortunato, E.} } @article {Raniero2004532, title = {Growth of polymorphous/nanocrystalline silicon films deposited by PECVD at 13.56 MHz}, journal = {Materials Science Forum}, volume = {455-456}, year = {2004}, note = {

cited By 1

}, pages = {532-535}, abstract = {

This paper aims to characterize the growth process of polymorphous/ nanocrystalline silicon (pm-Si:H) films produced by PECVD at 13.56 MHz. The emphasis is in determining the plasma parameters that allow to control the conditions where pm/nc-Si:H can be obtained under high hydrogen dilution, where the only varied parameter is the silane gas flow, fixing rf power, deposition pressure and substrate temperature. The data achieved show that good pm/nc-Si:H films are produced at 240 Pa using a silane gas flow of 5sccm (dilution 1:70) to which it corresponds films with photosensitivities exceeding 106, optical gaps close to 1.80 eV and 18 at\% hydrogen contents. The data also show that under certain deposition conditions the pm-Si:H films peel-off.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-3142691842\&partnerID=40\&md5=ac0873148a92df9e568cf3b31738847e}, author = {Raniero, L.a , Martins, R.a , {\'A}guas, H.a , Zang, S.a , Ferreira, I.a , Pereira, L.a , Fortunato, E.a , Boufendi, L.b} } @article {Fortunato2003121, title = {Growth of ZnO:Ga thin films at room temperature on polymeric substrates: Thickness dependence}, journal = {Thin Solid Films}, volume = {442}, number = {1-2}, year = {2003}, note = {

cited By 87

}, pages = {121-126}, abstract = {

In this paper, we present results concerning the thickness dependence (from 70 to 890 nm) of electrical, structural, morphological and optical properties presented by gallium-doped zinc oxide (GZO) deposited on polyethylene naphthalate (PEN) substrates by r.f. magnetron sputtering at room temperature. For thicknesses higher than 300 nm an independent correlation between the electrical, morphological, structural and optical properties are observed. The lowest resistivity obtained was 5 {\texttimes} 10-4 Ω cm with a sheet resistance of 15 Ω/□ and an average optical transmittance in the visible part of the spectra of 80\%. It is also shown that by passivating the surface of the polymer by depositing a thin silicon dioxide layer the electrical and structural properties of the films are improved nearly by a factor of two. {\textcopyright} 2003 Elsevier B.V. All rights reserved.

}, doi = {10.1016/S0040-6090(03)00958-1}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0141748181\&partnerID=40\&md5=b07f34491e4f94ad42e736f49e886524}, author = {Fortunato, E., Gon{\c c}alves, A., Assun{\c c}{\~a}o, V., Marques, A., {\'A}guas, H., Pereira, L., Ferreira, I., Martins, R.} } @article {Xu20061972, title = {Heterojunction solar cells with n-type nanocrystalline silicon emitters on p-type c-Si wafers}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 30

}, pages = {1972-1975}, abstract = {

Hydrogenated nanocrystalline silicon (nc-Si:H) n-layers have been used to prepare heterojunction solar cells on flat p-type crystalline silicon (c-Si) wafers. The nc-Si:H n-layers were deposited by radio-frequency (RF) plasma enhanced chemical vapor deposition (PECVD), and characterized using Raman spectroscopy, optical transmittance and activation energy of dark-conductivity. The nc-Si:H n-layers obtained comprise fine grained nanocrystallites embedded in amorphous matrix, which have a wider bandgap and a smaller activation energy. Heterojunction solar cells incorporated with the nc-Si n-layer were fabricated using configuration of Ag (100 nm)/lT0 (80 nm)/n-nc-Si:H (15 nm)/buffer a-Si:H/p-c-Si (300 μm)/Al (200 nm), where a very thin intrinsic a-Si:H buffer layer was used to passivate the p-c-Si surface, followed by a hydrogen plasma treatment prior to the deposition of the thin nanocrystalline layer. The results show that heterojunction solar cells subjected to these surface treatments exhibit a remarkable increase in the efficiency, up to 14.1\% on an area of 2.43 cm2. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2006.02.028}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33745474278\&partnerID=40\&md5=a326a153998c82a3f368b4fb20ff444e}, author = {Xu, Y.a , Hu, Z.b c , Diao, H.a , Cai, Y.c , Zhang, S.b , Zeng, X.a , Hao, H.a , Liao, X.a , Fortunato, E.b , Martins, R.b} } @article {Fortunato2004806, title = {High field-effect mobility zinc oxide thin film transistors produced at room temperature}, journal = {Journal of Non-Crystalline Solids}, volume = {338-340}, number = {1 SPEC. ISS.}, year = {2004}, note = {

cited By 98

}, pages = {806-809}, abstract = {

In this paper we present the first results of thin film transistors produced completely at room temperature using ZnO as the active channel and silicon oxynitride as the gate dielectric. The ZnO-based thin film transistors (ZnO-TFT) present an average optical transmission (including the glass substrate) of 84\% in the visible part of the spectrum. The ZnO-TFT operates in the enhancement mode with a threshold voltage of 1.8 V. A field effect mobility of 70 cm2/Vs, a gate voltage swing of 0.68 V/decade and an on-off ratio of 5{\texttimes}105 were obtained. The combination of transparency, high field-effect mobility and room temperature processing makes the ZnO-TFT very promising for the next generation of invisible and flexible electronics. {\textcopyright} 2004 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2004.03.096}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-2942622227\&partnerID=40\&md5=248b3866dd3fd9dd5f133c3104223b8f}, author = {Fortunato, E., Pimentel, A., Pereira, L., Gon{\c c}alves, A., Lavareda, G., {\'A}guas, H., Ferreira, I., Carvalho, C.N., Martins, R.} } @article {Pereira20081544, title = {High k dielectrics for low temperature electronics}, journal = {Thin Solid Films}, volume = {516}, number = {7}, year = {2008}, note = {

cited By 41

}, pages = {1544-1548}, abstract = {

In this work the electrical and structural properties of two high k materials as hafnium oxide (HfO2) and tantalum oxide (Ta2O5) produced at room temperature are exploited. Aiming low temperature processing two techniques were employed: r.f. sputtering and electron beam evaporation. The sputtered HfO2 films present a nanocrystalline structure when deposited at room temperature. The same does not happen for the evaporated films, which are essentially amorphous. The density and the electrical performance of both sputtered and evaporated films are improved after annealing them at 200~{\textdegree}C. On the other hand, the Ta2O5 samples deposited at room temperature are always amorphous, independently of the technique used. The density and electrical performance are not so sensitive to the annealing process. The set of data obtained show that these dielectrics processed at temperatures below 200~{\textdegree}C present promising properties aiming to produce devices at low temperature with improved interface properties and reduced leakage currents. {\textcopyright} 2007 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2007.03.088}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-38649119816\&partnerID=40\&md5=acd41a0cd2daf1ca74cbfc9acfc8e70d}, author = {Pereira, L.a , Barquinha, P.a , Fortunato, E.a , Martins, R.a , Kang, D.b , Kim, C.J.b , Lim, H.b , Song, I.b , Park, Y.b} } @article {Gonalves2009, title = {High mobility a-IGO films produced at room temperature and their application in TFTs}, journal = {Electrochemical and Solid-State Letters}, volume = {13}, number = {1}, year = {2009}, note = {

cited By 15

}, pages = {H20-H22}, abstract = {

The effect of oxygen partial pressure on the properties of In2 O3 - Ga2 O3 thin films produced by sputtering at room temperature aimed at thin film transistor (TFT) application is reported in this work. When produced in the absence of oxygen, the films are polycrystalline, while in the presence of oxygen, the films are amorphous. The films{\textquoteright} resistivity is tuned between 10-3 and 104 γ cm. Moreover, the films present a high transmittance (\> 80\%) and a smooth surface (rrms =1.2 nm). The high performance as-produced transistors present high saturation mobility (μsat ≈43 cm2 /V s) and a subthreshold gate-voltage swing of 0.51 V/dec, which is reduced to 0.27 V/dec after 150{\textdegree}C annealing. {\textcopyright} 2009 The Electrochemical Society.

}, doi = {10.1149/1.3257613}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-70450196874\&partnerID=40\&md5=3be86cbe74795ca09e8b7e8e2141e843}, author = {Gonalves, G.a , Barquinha, P.a , Pereira, L.b , Franco, N.c , Alves, E.c , Martins, R.b , Fortunato, E.a} } @article {Fortunato2006104, title = {High mobility amorphous/nanocrystalline indium zinc oxide deposited at room temperature}, journal = {Thin Solid Films}, volume = {502}, number = {1-2}, year = {2006}, note = {

cited By 47

}, pages = {104-107}, abstract = {

In this paper we present results of indium zinc oxide deposited at room temperature by rf magnetron sputtering, with an electron mobility as high as 60 cm2/Vs. The films present a resistivity as low as 5 {\texttimes} 10 - 4 Ω cm with an optical transmittance of 85\%. The structure of these films seems to be polymorphous (mix of different amorphous and nanocrystalline phases from different origins) as detected from XRD patterns with a smooth surface and from SEM micrographs, is highly important to ensure a long lifetime when used in display devices. {\textcopyright} 2005 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2005.07.311}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33344468567\&partnerID=40\&md5=8479a6a6eb6a32528f2c3d3d9429840f}, author = {Fortunato, E., Pimentel, A., Gon{\c c}alves, A., Marques, A., Martins, R.} } @article {Fortunato2008443, title = {High mobility and low threshold voltage transparent thin film transistors based on amorphous indium zinc oxide semiconductors}, journal = {Solid-State Electronics}, volume = {52}, number = {3}, year = {2008}, note = {

cited By 59

}, pages = {443-448}, abstract = {

Staggered bottom gate transparent thin film transistors (TTFTs) have been produced by rf magnetron sputtering at room temperature, using amorphous indium zinc oxide (IZO) semiconductor, for the channel as well as for the drain and source regions. The obtained TTFTs operate in the enhancement mode with threshold voltages of 2.4 V, saturation mobility of 22.7 cm2/V s, gate voltage swing of 0.44 V/dec and an ON/OFF current ratio of 7 {\texttimes} 107. The high performances presented by these TTFTs produced at room temperature, make these TFTs a promising candidate for flexible, wearable, disposable portable electronics as well as battery-powered applications. {\textcopyright} 2007 Elsevier Ltd. All rights reserved.

}, doi = {10.1016/j.sse.2007.10.032}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-39049125192\&partnerID=40\&md5=4bad0df856cb3b7ae46dfe1685a2b901}, author = {Fortunato, E., Barquinha, P., Gon{\c c}alves, G., Pereira, L., Martins, R.} } @article {Parthiban2012268, title = {High mobility and visible-near infrared transparent titanium doped indium oxide thin films produced by spray pyrolysis}, journal = {Thin Solid Films}, volume = {524}, year = {2012}, note = {

cited By 9

}, pages = {268-271}, abstract = {

This paper deals with high transparent and high conductive oxides based on polycrystalline titanium (Ti) doped (0.5-3 at.\%) indium oxide (IO) thin films produced on glass substrates at 400 {\textdegree}C by spray pyrolysis technique. X-ray diffraction analysis confirmed the cubic bixbyite structure of indium oxide. A high mobility of \~{} 97 cm2 V- 1 s- 1, a carrier concentration of \~{} 1.55 {\texttimes} 1020 cm- 3 and a resistivity of \~{} 4.11 {\texttimes} 10- 4 Ω-cm with \~{} 83\% of transmittance in the wavelength ranging between 400 and 2500 nm were obtained for 2 at.\% Ti doping films, rivalling so to the best known transparent conducting oxide based on indium tin oxide. Moreover, the transmittance in the broad wavelength ranging between 400 and 2500 nm is over 83\%, leading so to an increasing carrier generation towards the near infrared region of the spectrum, as required for applications such as solar cells. We also notice that increasing the doping concentration widened the optical band gap and caused a small Burstein-Moss shift, due to mobility decrease, as expected. {\textcopyright} 2012 Published by Elsevier B.V.

}, doi = {10.1016/j.tsf.2012.10.013}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84869497494\&partnerID=40\&md5=bf4b11ed59cd80ff248a60ebc67a16d3}, author = {Parthiban, S.a b , Gokulakrishnan, V.a , Elangovan, E.b , Gon{\c c}alves, G.b , Ramamurthi, K.a c , Fortunato, E.b , Martins, R.b} } @article {Fortunato2008, title = {High mobility indium free amorphous oxide thin film transistors}, journal = {Applied Physics Letters}, volume = {92}, number = {22}, year = {2008}, note = {

cited By 114

}, abstract = {

High mobility bottom gate thin film transistors (TFTs) with an amorphous gallium tin zinc oxide (a-GSZO) channel layer have been produced by rf magnetron cosputtering using a gallium zinc oxide (GZO) and tin (Sn) targets. The effect of postannealing temperatures (200, 250, and 300 {\textdegree}C) was evaluated and compared with two series of TFTs produced at room temperature (S1) and 150 {\textdegree}C (S2) during the channel deposition. From the results, it was observed that the effect of postannealing is crucial for both series of TFTs either for stability as well as for improving the electrical characteristics. The a-GSZO TFTs (WL=5050 μm) operate in the enhancement mode (n -type), present a high saturation mobility of 24.6 cm2 V s, a subthreshold gate swing voltage of 0.38 V /decade, a turn-on voltage of -0.5 V, a threshold voltage of 4.6 V, and an Ion Ioff ratio of 8{\texttimes} 107, satisfying all the requirements to be used as active-matrix backplane. {\textcopyright} 2008 American Institute of Physics.

}, doi = {10.1063/1.2937473}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-44849134063\&partnerID=40\&md5=6c8d19d68588584757582e0cc5ab241d}, author = {Fortunato, E.M.C.a , Pereira, L.M.N.a , Barquinha, P.M.C.a , Botelho Do Rego, A.M.b , Gonalves, G.a , Vil̀, A.c , Morante, J.R.c} } @article {Parthiban2009, title = {High near-infrared transparency and carrier mobility of Mo doped In2 O 3 thin films for optoelectronics applications}, journal = {Journal of Applied Physics}, volume = {106}, number = {6}, year = {2009}, note = {

cited By 10

}, abstract = {

Molybdenum (0-1 at. \%) doped indium oxide thin films with high near-infrared (NIR) transparency and high carrier mobility were deposited on Corning-1737 glass substrates at 400 {\textdegree}C by a spray pyrolysis experimental technique. X-ray diffraction (XRD) analysis confirmed the cubic bixbyite structure of indium oxide. The preferred growth orientation along the (222) plane for the low Mo doping level (0.5 at. \%) shifts to (400) for higher Mo doping levels (\<0.6 at. \%). The crystallite size extracted from the XRD data corroborates the changes in full width at half maximum due to the variation in Mo doping. A scanning electron microscopy study illustrated the evolution in the surface microstructure as a function of Mo doping. The negative sign of the Hall coefficient confirmed the n -type conductivity. A high carrier mobility of \~{}122.4 cm2 /V s, a carrier concentration of \~{}9.5{\texttimes} 1019 cm-3, a resistivity of \~{}5.3{\texttimes} 10-4cm, and a high figure of merit of \~{}4.2{\texttimes} 10-2 -1 are observed for the films deposited with 0.5 at. \% Mo. The obtained high average transparency of \~{}83\% in the wavelengths ranging from 400 to 2500 nm confirmed the extension of transmittance well into the NIR region. {\textcopyright} 2009 American Institute of Physics.

}, doi = {10.1063/1.3224946}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-70349640168\&partnerID=40\&md5=daa23c1256806a2aa5b3a7e712d84153}, author = {Parthiban, S.a , Elangovan, E.b , Ramamurthi, K.a , Martins, R.b , Fortunato, E.b} } @article {Parthiban200992, title = {High near-infrared transparent molybdenum-doped indium oxide thin films for nanocrystalline silicon solar cell applications}, journal = {Solar Energy Materials and Solar Cells}, volume = {93}, number = {1}, year = {2009}, note = {

cited By 45

}, pages = {92-97}, abstract = {

Molybdenum-doped indium oxide (IMO) thin films were deposited at 450 {\textdegree}C for varying molybdenum concentrations in the range of 0.5-2 at\% by the spray pyrolysis technique. These films confirmed the cubic bixbyite structure of polycrystalline In2O3. The preferred growth orientation along the (2 2 2) plane shifts to (4 0 0) on higher Mo doping levels. The films doped with 0.5 at\% Mo showed high mobility of 76.9 cm2/(V s). The high visible transmittance extends well into the near-infrared region. A possibility of using the produced IMO films in nanocrystalline (nc) silicon solar cell applications is discussed in this article. The morphological studies showed a change in the microstructure, which is consistent with the change in crystallographic orientation. {\textcopyright} 2008 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.solmat.2008.08.007}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-55949083642\&partnerID=40\&md5=714230ff7ff7ebe1d50fc97c05b240c3}, author = {Parthiban, S.a , Gokulakrishnan, V.a , Ramamurthi, K.a , Elangovan, E.b , Martins, R.b , Fortunato, E.b , Ganesan, R.c} } @article {A{\'A}guas200226, title = {High quality a-Si:H films for MIS device applications}, journal = {Thin Solid Films}, volume = {403}, number = {404}, year = {2002}, note = {

cited By 10

}, pages = {26-29}, abstract = {

This work presents the I-V results of a-Si:H/SiOx/Pd MIS (metal-insulator-semiconductor) structures. The a-Si:H was deposited by non-conventional modified triode PECVD. This new configuration allows the deposition of high quality a-Si:H with a photosensitivity of 106, indicating the presence of low density of defects. Spectroscopic ellipsometry measurements revealed that these films are highly dense and present a very smooth surface so allowing a low defect interface between the Pd and the a-Si:H. As a result, we could make MIS photodiodes with barrier heights of 1.17 eV, which give a high reduction of the reverse dark current, an increase of the signal to noise ratio of 106 and an open circuit voltage VOC = 0.5 V. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0040-6090(01)01655-8}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-15744375197\&partnerID=40\&md5=e0071e4075ebd42a1eb5e85fd9f0d608}, author = {A{\'A}guas, H., Fortunato, E., Silva, V., Pereira, L., Martins, R.} } @article {Fortunato2004443, title = {High quality conductive gallium-doped zinc oxide films deposited at room temperature}, journal = {Thin Solid Films}, volume = {451-452}, year = {2004}, note = {

cited By 93

}, pages = {443-447}, abstract = {

Transparent and highly conducting gallium-doped zinc oxide films were successfully deposited by rf sputtering at room temperature. The lowest resistivity achieved was 2.6{\texttimes}10-4 Ω cm for a thickness of 1100 nm (sheet resistance ≈1.6 Ω/sq), with a Hall mobility of 18 cm2/Vs and a carrier concentration of 1.3{\texttimes}1021 cm-3. The films are polycrystalline with a hexagonal structure and a strongly preferred orientation along the c-axis. A linear dependence between the mobility and the crystallite size was obtained. The films present a transmittance in the visible spectra between 80 and 90\% and a refractive index of approximately 2, which is very close to the value reported for bulk material. {\textcopyright} 2003 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2003.10.139}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-10444242593\&partnerID=40\&md5=d967d4ba2c56900c473a8466ee8f6c1f}, author = {Fortunato, E.a , Assun{\c c}{\~a}o, V.a , Gon{\c c}alves, A.a , Marques, A.a , {\'A}guas, H.a , Pereira, L.a , Ferreira, I.a , Vilarinho, P.b , Ma} } @article {Parthiban20083217, title = {High-mobility molybdenum doped indium oxide thin films prepared by spray pyrolysis technique}, journal = {Materials Letters}, volume = {62}, number = {17-18}, year = {2008}, note = {

cited By 13

}, pages = {3217-3219}, abstract = {

Molybdenum doped indium oxide (IMO) thin films were deposited on the glass substrates preheated to 450~{\textdegree}C by spray pyrolysis technique. The Mo doping was varied between 0 and 2.0~at.\%. The films were characterized by their structural, electrical and optical properties. The films are confirmed to be cubic bixbyite In2O3 with a strongest orientation along (222) plane, which is shifted to (400) plane for the increase in Mo doping to 1.25 and 2~at.\%. The film deposited with 0.5~at.\% Mo doping shows high mobility of 76.9~cm2V- 1s- 1 , resistivity of 1.8 {\texttimes} 10- 3 Ω-cm and high carrier concentration of 4.6 {\texttimes} 1019~cm- 3 with 81.3\% transmittance in the visible range between 500 and 800~nm. Further, the transparency extents well into the near-IR range. {\textcopyright} 2008 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.matlet.2008.02.022}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-43049176779\&partnerID=40\&md5=d968125b017a6f26dcc04872a5051f24}, author = {Parthiban, S.a , Ramamurthi, K.a , Elangovan, E.b , Martins, R.b , Fortunato, E.b , Ganesan, R.c} } @article {Shan20169438, title = {High-mobility p-type NiOx thin-film transistors processed at low temperatures with Al2O3 high-k dielectric}, journal = {Journal of Materials Chemistry C}, volume = {4}, number = {40}, year = {2016}, note = {

cited By 0

}, pages = {9438-9444}, abstract = {

Although there are a few research studies on solution-processed p-channel oxide thin-film transistors (TFTs), the strict fabrication conditions and the poor electrical properties have limited their applications in low-power complementary metal oxide semiconductor (CMOS) electronics. Here, the application of the polyol reduction method for processing p-type CuxO and NiOx channel layers and their implementation in TFT devices are reported. The optimized CuxO and NiOx TFTs were achieved at low annealing temperatures (\~{}300 {\textdegree}C) and exhibited decent electrical properties. Encouraged by the inspiring results obtained on SiO2/Si substrates, the TFT performance was further optimized by device engineering, employing high-k AlOx as the gate dielectric. The fully solution-processed NiOx/AlOx TFT could be operated at a low voltage of 3.5 V and exhibits a high hole mobility of around 25 cm2 V-1 s-1. Our work demonstrates the ability to grow high-quality p-type oxide films and devices via the polyol reduction method over large area substrates while at the same time it provides guidelines for further p-type oxide material and device improvements. {\textcopyright} The Royal Society of Chemistry 2016.

}, doi = {10.1039/c6tc02137a}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991618970\&partnerID=40\&md5=ab37573d2ea705b3ded8143a3509364e}, author = {Ao Liu, Guoxia Liu, Huihui Zhu, Byoungchul Shin, Elvira Fortunato,Rodrigo Martins and Fukai Shan} } @article {Fortunato2008988, title = {High-performance flexible hybrid field-effect transistors based on cellulose fiber paper}, journal = {IEEE Electron Device Letters}, volume = {29}, number = {9}, year = {2008}, note = {

cited By 134

}, pages = {988-990}, abstract = {

In this letter, we report for the first time the use of a sheet of cellulose-fiber-based paper as the dielectric layer used in oxide-based semiconductor thin-film field-effect transistors (FETs). In this new approach, we are using the cellulose-fiber-based paper in an "interstrate"structure since the device is built on both sides of the cellulose sheet. Such hybrid FETs present excellent operating characteristics such as high channel saturation mobility (\> 30 cm2Vs), drain-source current on/off modulation ratio of approximately 104, near-zero threshold voltage, enhancement n-type operation, and subthreshold gate voltage swing of 0.8 V/decade. The cellulose-fiber-based paper FETs{\textquoteright} characteristics have been measured in air ambient conditions and present good stability, after two months of being processed. The obtained results outpace those of amorphous Si thin-film transistors (TFTs) and rival with the same oxide-based TFTs produced on either glass or crystalline silicon substrates. The compatibility of these devices with large-scale/large-area deposition techniques and low-cost substrates as well as their very low operating bias delineates this as a promising approach to attain high-performance disposable electronics like paper displays, smart labels, smart packaging, RFID, and point-of-care systems for self-analysis in bioapplications, among others. {\textcopyright} 2008 IEEE.

}, doi = {10.1109/LED.2008.2001549}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-50649121902\&partnerID=40\&md5=6d364135722805ba83895d860d8fbd4a}, author = {Fortunato, E., Correia, N., Barquinha, P., Pereira, L., Goncalves, G., Martins, R.} } @article {Martins199747, title = {Highly conductive and highly transparent n-type microcrystalline silicon thin films}, journal = {Thin Solid Films}, volume = {303}, number = {1-2}, year = {1997}, note = {

cited By 28

}, pages = {47-52}, abstract = {

The aim of this paper is to present data on the dependence of the electro-optical characteristics and structure of n-type microcrystalline silicon films on the r.f. power used during the deposition of films produced by the plasma-enhanced chemical vapour deposition technique. The interest of these films arise from the fact that they combine some electro-optical advantages of amorphous (wide optical gap) and crystalline materials (electronic behaviour), highly interesting in the production of a wide variety of optoelectronic devices such as solar cells and thin film transistors. In this paper, microcrystalline n-type films presenting simultaneously optical gaps of about 2.3 eV, dark conductivity of 6.5 S cm-1 and Hall mobility of about 0.86 cm2 V-1 s-1 will be reported, the highest combined values for n-type microcrystalline silicon films, as far as we know. {\textcopyright} 1997 Elsevier Science S.A.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031189816\&partnerID=40\&md5=f57ae029230f79b04e978092e6fe78c4}, author = {Martins, R., Ma{\c c}arico, A., Ferreira, I., Nunes, R., Bicho, A., Fortunato, E.} } @article {Deuermeier2016, title = {Highly conductive grain boundaries in copper oxide thin films}, journal = {Journal of Applied Physics}, volume = {119}, number = {23}, year = {2016}, note = {

cited By 0

}, abstract = {

High conductivity in the off-state and low field-effect mobility compared to bulk properties is widely observed in the p-type thin-film transistors of Cu2O, especially when processed at moderate temperature. This work presents results from in situ conductance measurements at thicknesses from sub-nm to around 250 nm with parallel X-ray photoelectron spectroscopy. An enhanced conductivity at low thickness is explained by the occurrence of Cu(II), which is segregated in the grain boundary and locally causes a conductivity similar to CuO, although the surface of the thick film has Cu2O stoichiometry. Since grains grow with an increasing film thickness, the effect of an apparent oxygen excess is most pronounced in vicinity to the substrate interface. Electrical properties of Cu2O grains are at least partially short-circuited by this effect. The study focuses on properties inherent to copper oxide, although interface effects cannot be ruled out. This non-destructive, bottom-up analysis reveals phenomena which are commonly not observable after device fabrication, but clearly dominate electrical properties of polycrystalline thin films. {\textcopyright} 2016 Author(s).

}, doi = {10.1063/1.4954002}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975528044\&partnerID=40\&md5=6d2413a6ed1db4c168184b45693ffe3e}, author = {Deuermeier, J.a b , Wardenga, H.F.b , Morasch, J.b , Siol, S.b c , Nandy, S.a , Calmeiro, T.a , Martins, R.a , Klein, A.b , Fort} } @article {Filonovich20091253, title = {Highly conductive p-type nanocrystalline silicon films deposited by RF-PECVD using silane and trimethylboron mixtures at high pressure}, journal = {Vacuum}, volume = {83}, number = {10}, year = {2009}, note = {

cited By 21

}, pages = {1253-1256}, abstract = {

In this paper we present a study of boron-doped nc-Si:H films prepared by PECVD at high deposition pressure (>=4 mbar), high plasma power and low substrate temperature (<=200 {\textdegree}C) using trimethylboron (TMB) as a dopant gas. The influence of deposition parameters on electrical, structural and optical properties is investigated. We determine the deposition conditions that lead to the formation of p-type nanocrystalline silicon thin films with very high crystallinity, high value of dark conductivity (\>7 (Ω cm)-1) and high optical band gap (>=1.7 eV). Modeling of ellipsometry spectra reveals that the film growth mechanism should proceed through a sub-surface layer mechanism that leads to silicon crystallization. The obtained films are very good candidates for application in amorphous and nanocrystalline silicon solar cells as a p-type window layer. {\textcopyright} 2009 Elsevier Ltd. All rights reserved.

}, doi = {10.1016/j.vacuum.2009.03.017}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67349209304\&partnerID=40\&md5=ac577d7c2e50fb1eee744ef215342ef6}, author = {Filonovich, S.A.a , {\'A}guas, H.a b , Bernacka-Wojcik, I.b , Gaspar, C.a , Vilarigues, M.c , Silva, L.B.a b , Fortunato, E.a b , Ma} } @article {Fortunato2002571, title = {Highly conductive/transparent ZnO:Al thin films deposited at room temperature by rf magnetron sputtering}, journal = {Key Engineering Materials}, volume = {230-232}, year = {2002}, note = {

cited By 2

}, pages = {571-574}, abstract = {

Transparent conducting ZnO:Al thin films have been deposited on polyester (Mylar type D, 100 μm thickness) substrates at room temperature by r.f. magnetron sputtering. The structural, optical and electrical properties of the deposited films have been studied. The samples are polycrystalline with a hexagonal wurtzite structure and a strong crystallographic c-axis orientation (002) perpendicular to the substrate surface. As deposited ZnO:Al thin films have an 85\% transmittance in the visible and infra-red region and a resistivity as low as 3.6{\texttimes}10-2 Ωcm. The obtained results are comparable to those ones obtained on glass substrates, opening a new field for low cost, light weight, small volume, flexible and unbreakable large area optoelectronic devices.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036430969\&partnerID=40\&md5=4707bff758272157d0869b0e2fc96fe3}, author = {Fortunato, E., Nunes, P., Marques, A., Costa, D., {\'A}guas, H., Ferreira, I., Costa, M.E.V., Martins, R.} } @article {Bender2003, title = {Highly sensitive ZnO ozone detectors at room temperature}, journal = {Japanese Journal of Applied Physics, Part 2: Letters}, volume = {42}, number = {4 B}, year = {2003}, note = {

cited By 43

}, pages = {L435-L437}, abstract = {

In this letter we compare the room temperature ozone sensing properties of intrinsic zinc oxide (ZnO) thin films deposited by spray pyrolysis, dc and r.f. magnetron sputtering. Their sensor response exceeds 8 orders of magnitude when the film structure is constituted by nanocrystallites. These preliminary results clearly demonstrate that the films could be potentially used for ozone detection at room temperature.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0038207841\&partnerID=40\&md5=88e2ed26b61886fca5e3da98290c25e7}, author = {Bender, M.a , Fortunato, E.b , Nunes, P.b , Ferreira, I.b , Marques, A.b , Martins, R.b , Katsarakis, N.a , Cimalla, V.a , Kiria} } @article {Fortunato20081605, title = {Highly stable transparent and conducting gallium-doped zinc oxide thin films for photovoltaic applications}, journal = {Solar Energy Materials and Solar Cells}, volume = {92}, number = {12}, year = {2008}, note = {

cited By 105

}, pages = {1605-1610}, abstract = {

Transparent and highly conducting gallium zinc oxide (GZO) films were successfully deposited by RF sputtering at room temperature. A lowest resistivity of\~{}2.8 {\texttimes} 10-4 ωcm was achieved for a film thickness of 1100nm (sheet resistance \~{}2.5ω/□), with a Hall mobility of 18cm2/Vs and a carrier concentration of 1.3 {\texttimes} 1021 cm-3. The films are polycrystalline with a hexagonal structure having a strong crystallographic c-axis orientation. A linear dependence between the mobility and the crystallite size was obtained. The films are highly transparent (between 80\% and 90\% including the glass substrate) in the visible spectra with a refractive index of about 2, very similar to the value reported for the bulk material. These films were applied to single glass/TCO/pin hydrogenated amorphous silicon solar cells as front layer contact, leading to solar cells with efficiencies of about 9.52\%. With the optimized deposition conditions, GZO films were also deposited on polymer (PEN) substrates and the obtained results are discussed. {\textcopyright} 2008 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.solmat.2008.07.009}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-55349105422\&partnerID=40\&md5=ca3eaba7c227d48034c9f7dc8a353916}, author = {Fortunato, E., Raniero, L., Siva, L., Gon{\c c}alves, A., Pimentel, A., Barquinha, P., {\'A}guas, H., Pereira, L., Gon{\c c}alves, G., Ferreir} } @article {Sanematsu1985281, title = {Highly uniform large-area a-Si:H films}, journal = {Solar Cells}, volume = {14}, number = {3}, year = {1985}, note = {

cited By 0

}, pages = {281-287}, abstract = {

A double-chamber system was used to deposit large-area hydrogenated amorphous silicon films for photovoltaic applications. The electro-optical characterisation of films of area 400 cm2 deposited on glass substrates is described in this paper. The deposition rate of the films is dependent on the r.f. power delivered, the substrate bias and the partial pressure of the reactive gas. The film thickness was observed to have a uniformity of better than 0.5\%. The best film quality was obtained for a deposition rate of about 1.5 {\r A} s-1. The optical gap, activation energy, photosensitivity, density of gap states and hydrogen content were determined. {\textcopyright} 1985.

}, doi = {10.1016/0379-6787(85)90063-8}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0022097384\&partnerID=40\&md5=92519ecd2efd48be0eb0f468c530d528}, author = {Sanematsu, M.S.a , Pereyra, I.a , Andrade, A.M.a , Martins, R.F.P.b} } @article {Liu2016, title = {Hole mobility modulation of solution-processed nickel oxide thin-film transistor based on high-k dielectric}, journal = {Applied Physics Letters}, volume = {108}, number = {23}, year = {2016}, note = {

cited By 0

}, abstract = {

Solution-processed p-type oxide semiconductors have recently attracted increasing interests for the applications in low-cost optoelectronic devices and low-power consumption complementary metal-oxide-semiconductor circuits. In this work, p-type nickel oxide (NiOx) thin films were prepared using low-temperature solution process and integrated as the channel layer in thin-film transistors (TFTs). The electrical properties of NiOx TFTs, together with the characteristics of NiOx thin films, were systematically investigated as a function of annealing temperature. By introducing aqueous high-k aluminum oxide (Al2O3) gate dielectric, the electrical performance of NiOx TFT was improved significantly compared with those based on SiO2 dielectric. Particularly, the hole mobility was found to be 60 times enhancement, quantitatively from 0.07 to 4.4 cm2/V s, which is mainly beneficial from the high areal capacitance of the Al2O3 dielectric and high-quality NiOx/Al2O3 interface. This simple solution-based method for producing p-type oxide TFTs is promising for next-generation oxide-based electronic applications. {\textcopyright} 2016 Author(s).

}, doi = {10.1063/1.4953460}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84974623209\&partnerID=40\&md5=5175cf435ed8257a8148ba904ce90163}, author = {Liu, A.a b c , Liu, G.a b c , Zhu, H.a b c , Shin, B.d , Fortunato, E.e , Martins, R.e , Shan, F.a b c} } @article {Ferreira20021644, title = {Hot-wire plasma assisted chemical vapor deposition: A deposition technique to obtain silicon thin films}, journal = {Journal of Applied Physics}, volume = {91}, number = {3}, year = {2002}, note = {

cited By 2

}, pages = {1644-1649}, abstract = {

We have produced amorphous intrinsic silicon thin films by hot-wire plasma assisted chemical vapor deposition, a process that combines the traditional rf plasma and the recent hot-wire techniques. In this work we have studied the influence of hydrogen gas dilution and rf power on the surface morphology, composition, structure and electro-optical properties of these films. The results show that by using this deposition technique it is possible to obtain at moderate rf power and filament temperature, compact i-type silicon films with ημτ of the order of 10 -5cm 2V -1, without hydrogen dilution. {\textcopyright} 2002 American Institute of Physics.

}, doi = {10.1063/1.1427133}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036469595\&partnerID=40\&md5=17f7cba0f0472208f334da09ecaa3246}, author = {Ferreira, I.a , Fortunato, E.a , Martins, R.a , Vilarinho, P.b} } @article {Pereira2016, title = {Hybrid microfluidic platform for multifactorial analysis based on electrical impedance, refractometry, optical absorption and fluorescence}, journal = {Micromachines}, volume = {7}, number = {10}, year = {2016}, note = {

cited By 0

}, abstract = {

This paper describes the development of a novel microfluidic platform for multifactorial analysis integrating four label-free detection methods: electrical impedance, refractometry, optical absorption and fluorescence. We present the rationale for the design and the details of the microfabrication of this multifactorial hybrid microfluidic chip. The structure of the platform consists of a three-dimensionally patterned polydimethylsiloxane top part attached to a bottom SU-8 epoxy-based negative photoresist part, where microelectrodes and optical fibers are incorporated to enable impedance and optical analysis. As a proof of concept, the chip functions have been tested and explored, enabling a diversity of applications: (i) impedance-based identification of the size of micro beads, as well as counting and distinguishing of erythrocytes by their volume or membrane properties; (ii) simultaneous determination of the refractive index and optical absorption properties of solutions; and (iii) fluorescence-based bead counting. {\textcopyright} 2016 by the authors.

}, doi = {10.3390/mi7100181}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994806266\&partnerID=40\&md5=9cb2f515d97d841aa47098991229776e}, author = {Pereira, F.M.a b , Bernacka-Wojcik, I.a e , Ribeiro, R.S.R.c d , Lobato, M.T.a , Fortunato, E.a , Martins, R.a , Igreja, R.a , J} } @article {Filonovich2012, title = {Hydrogen plasma treatment of very thin p-type nanocrystalline Si films grown by RF-PECVD in the presence of B(CH 3) 3}, journal = {Science and Technology of Advanced Materials}, volume = {13}, number = {4}, year = {2012}, note = {

cited By 6

}, abstract = {

We have characterized the structure and electrical properties of p-type nanocrystalline silicon films prepared by radio-frequency plasma-enhanced chemical vapor deposition and explored optimization methods of such layers for potential applications in thin-film solar cells. Particular attention was paid to the characterization of very thin (\~{}20nm) films. The cross-sectional morphology of the layers was studied by fitting the ellipsometry spectra using a multilayer model. The results suggest that the crystallization process in a high-pressure growth regime is mostly realized through a subsurface mechanism in the absence of the incubation layer at the substrate-film interface. Hydrogen plasma treatment of a 22-nm-thick film improved its electrical properties (conductivity increased more than ten times) owing to hydrogen insertion and Si structure rearrangements throughout the entire thickness of the film. {\textcopyright} 2012 National Institute for Materials Science.

}, doi = {10.1088/1468-6996/13/4/045004}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84866330763\&partnerID=40\&md5=faa3cf51aea297c7aa2acaa5367f596c}, author = {Filonovich, S.A.a , {\'A}guas, H.a , Busani, T.a , Vicente, A.a , Ara{\'u}jo, A.a , Gaspar, D.a , Vilarigues, M.b , Leit{\~a}o, J.c , Fortun} } @article {Hu20061900, title = {Hydrogenated p-type nanocrystalline silicon in amorphous silicon solar cells}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 30

}, pages = {1900-1903}, abstract = {

A wide bandgap and highly conductive p-type hydrogenated nanocrystalline silicon (nc-Si:H) window layer was prepared with a conventional RF-PECVD system under large H dilution condition, moderate power density, high pressure and low substrate temperature. The optoelectrical and structural properties of this novel material have been investigated by Raman and UV-VIS transmission spectroscopy measurements indicating that these films are composed of nanocrystallites embedded in amorphous SiHx matrix and with a widened bandgap. The observed downshift of the optical phonon Raman spectra (514.4 cm-1) from crystalline Si peak (521 cm-1) and the widening of the bandgap indicate a quantum confinement effect from the Si nanocrystallites. By using this kind of p-layer, a-Si:H solar cells on bare stainless steel foil in nip sequence have been successfully prepared with a Voc of 0.90 V, a fill factor of 0.70 and an efficiency of 9.0\%, respectively. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2006.02.010}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33744783361\&partnerID=40\&md5=00f78aa341d6d359bb06b599ee44ccce}, author = {Hu, Z.a b c , Liao, X.a , Diao, H.a , Cai, Y.b , Zhang, S.c , Fortunato, E.c , Martins, R.c} } @article {Ferreira20061361, title = {Hydrogenated silicon carbon nitride films obtained by HWCVD, PA-HWCVD and PECVD techniques}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 19

}, pages = {1361-1366}, abstract = {

Hydrogenated silicon carbon nitride (SiCN:H) thin film alloys were produced by hot wire (HWCVD), plasma assisted hot wire (PA-HWCVD) and plasma enhanced chemical vapor (PECVD) deposition techniques using a Ni buffer layer as catalyst for inducing crystallization. The silicon carbon nitride films were grown using C2H4, SiH4 and NH3 gas mixtures and a deposition temperature of 300 {\textdegree}C. Prior to the deposition of the SiCN:H film a hydrogen etching of 10 min was performed in order to etch the catalyst material and to facilitate the crystallization. We report the influence of each deposition process on compositional, structural and morphological properties of the films. Scanning Electron Microscope-SEM and Atomic Force Measurement-AFM images show their morphology; the chemical composition was obtained by Rutherford Backscattering Spectrometry-RBS, Elastic Recoil Detection-ERD and the structure by Infrared-IR analysis. The thickness of the catalyst material determines the growth process and whether or not islands form. The production of micro-structured SiCN:H films is also dependent on the gas pressure, gas mixture and deposition process used. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2006.02.025}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33745494849\&partnerID=40\&md5=c3510ac11e11f6e6960b92b2aaed6572}, author = {Ferreira, I.a , Fortunato, E.a , Vilarinho, P.b , Viana, A.S.c , Ramos, A.R.d , Alves, E.d , Martins, R.a} } @article {Guimar{\~a}es1989789, title = {Hydrogenated thin film silicon semiconductors produced by a two consecutive decomposition and deposition chamber system}, journal = {Vacuum}, volume = {39}, number = {7-8}, year = {1989}, note = {

cited By 1

}, pages = {789-790}, abstract = {

Undoped and doped hydrogenated amorphous silicon semiconductors (a-Si:H) have been produced by a two consecutive decomposition deposition chamber (TCDDC) system assisted by electromagnetic static fields. Through this technique, a spatial separation is achieved between the plasma chemistry and that of the deposition to avoid ion and electron (with high energies) bombardment on the growing surface. Besides this, the use of a static magnetic field perpendicular to the substrate will promote plasma confinement, so avoiding its contamination by residual gases adsorbed on the reactor walls. On the other hand, the use of two grids dc biased in the deposition chamber, will allow control of the main film precursors, responsible for the electro-optical and structural properties of deposited films. In this paper we shall discuss the deposition method used as well as the transport, structural and morphological properties presented by deposited films and its dependence on deposition parameters used. {\textcopyright} 1989.

}, doi = {10.1016/0042-207X(89)90038-9}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024915137\&partnerID=40\&md5=8dc43b962dd4015365b5ff1a0e051b1d}, author = {Guimar{\~a}es, L., Martins, R., Santos, M., Ma{\c c}arico, A., Carvalho, N., Fortunato, E., Vieira, M.} } @article {Martins20082580, title = {Identification of unamplified genomic DNA sequences using gold nanoparticle probes and a novel thin film photodetector}, journal = {Journal of Non-Crystalline Solids}, volume = {354}, number = {19-25}, year = {2008}, note = {

cited By 7

}, pages = {2580-2584}, abstract = {

This paper describes a novel colorimetric method for detection of nucleic acid targets in a homogeneous format with improved sensitivity by means of a system based on the combination of a tunable monochromatic light source and an amorphous/nanocrystalline silicon photodetector that detects color and light intensity changes undergone by samples/assays containing tailored gold nanoparticles probes. This new low cost, portable, fast and simple optoelectronic platform, with the possibility to be re-used, permits detection of at least 400 fentomole of specific DNA sequences without target or signal amplification and was applied to the rapid detection of human pathogens in large variety of clinical samples such as Mycobacterium tuberculosis. {\textcopyright} 2008 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2007.09.074}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-43049117461\&partnerID=40\&md5=e463cecb6fa64b0984a4de8b23a0e711}, author = {Martins, R.a , Baptista, P.b , Silva, L.a , Raniero, L.a d , Doria, G.b c , Franco, R.c , Fortunato, E.a} } @article {Pereira20061737, title = {Impedance study of the electrical properties of poly-Si thin film transistors}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 4

}, pages = {1737-1740}, abstract = {

The aim of this work is to study the electrical characteristics of polycrystalline silicon (poly-Si) thin film transistors (TFTs) using spectroscopic impedance technique, where the poly-Si active layer was obtained by metal induced crystallization of amorphous silicon. From the study performed a theoretical model that fitted the impedance data is proposed, in order to obtain the separate contributions of each region that constitutes the TFT namely the channel, non accumulated region and contacts. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2006.01.066}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33745454055\&partnerID=40\&md5=e6cf3e25b2383f0c6528bcefe983fda4}, author = {Pereira, L., Raniero, L., Barquinha, P., Fortunato, E., Martins, R.} } @article {Martins20001094, title = {Improvement of a-Si:H device stability and performances by proper design of the interfaces}, journal = {Journal of Non-Crystalline Solids}, volume = {266-269 B}, year = {2000}, note = {

cited By 6

}, pages = {1094-1098}, abstract = {

This paper deals with a new design method for the interfaces of a-Si:H pin solar cells that improves the stability and performances of devices deposited in a single batch chamber process. The method consists in removing a deposited sacrificial layer placed between the p/i and/or i/n interfaces by etching. This layer is an absorber of defects and impurities that are introduced in the interfaces, mainly from the chamber walls cross-contamination and the substrate surface. The results achieved increase the device fill factor and short circuit current density, respectively towards 75\% and 16.3 mA cm-2, with a final efficiency of about 10\%, before light soaking experiments. {\textcopyright} 2000 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0022-3093(99)00909-6}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0007246306\&partnerID=40\&md5=e7fcbcb5287125fa7f583fd30e4a5f77}, author = {Martins, R., Ferreira, I., Cabrita, A., Fortunato, E.} } @article {Kiazadeh2016, title = {Improving positive and negative bias illumination stress stability in parylene passivated IGZO transistors}, journal = {Applied Physics Letters}, volume = {109}, number = {5}, year = {2016}, note = {

cited By 0

}, abstract = {

The impact of a parylene top-coating layer on the illumination and bias stress instabilities of indium-gallium-zinc oxide thin-film transistors (TFTs) is presented and discussed. The parylene coating substantially reduces the threshold voltage shift caused by continuous application of a gate bias and light exposure. The operational stability improves by 75\%, and the light induced instability is reduced by 35\%. The operational stability is quantified by fitting the threshold voltage shift with a stretched exponential model. Storage time as long as 7 months does not cause any measurable degradation on the electrical performance. It is proposed that parylene plays not only the role of an encapsulation layer but also of a defect passivation on the top semiconductor surface. It is also reported that depletion-mode TFTs are less sensitive to light induced instabilities. This is attributed to a defect neutralization process in the presence of free electrons. {\textcopyright} 2016 Author(s).

}, doi = {10.1063/1.4960200}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981155175\&partnerID=40\&md5=ab02bba3454e040f574ba707d0f5408e}, author = {Kiazadeh, A.a b , Gomes, H.L.b c , Barquinha, P.a , Martins, J.a , Rovisco, A.a , Pinto, J.V.a , Martins, R.a , Fortunato, E.a} } @article {Elangovan20092123, title = {Indium molybdenum oxide thin films: A comparative study by two different RF sputtering systems}, journal = {Physica Status Solidi (A) Applications and Materials Science}, volume = {206}, number = {9}, year = {2009}, note = {

cited By 3

}, pages = {2123-2127}, abstract = {

Indium molybdenum oxide thin films were deposited using different radio-frequency sputtering units on glass substrates at room temperature from an In 2O 3 (95 wt.\%): Mo (5 wt.\%) target. The film thickness ranges between 160 and 275 nm. The chamber volume of Unit-1 was ̃2.4 times larger than that of Unit-2. Apart from the chamber volume, a significant difference between the two units was the sputtering pressure. The films were characterized by their structural, morphological, optical, and electrical properties. A strong reflection from (222) plane was obtained for the ̃275 nm thick films deposited in Unit-1. The films deposited with \<275 nm thickness and those deposited in Unit-2 are close to amorphous with a small crystalline fraction. The surface of the films deposited in Unit-1 is comprised of randomly arranged crystallites, which is restructured with the increasing film thickness to become a well defined "rice field" like structure (275 nm thick). The films deposited in Unit-2 are comprised of many holes on the surface that is presumably due to back sputtering. The average visible transmittance calculated in the wavelength between 400 and 800 nm ranges from 70 to 82\%. The optical band gap is found to vary between 3.80 and 3.86 eV. The lowest bulk resistivity of the films deposited in Unit-1 was increased from ̃4.06{\texttimes}10 -3 to 4.07{\texttimes}10 -1ωcm when deposited in Unit-2. The carrier concentration was decreased from 1.31{\texttimes}10 20 to 1.03{\texttimes}10 18 cm -3 but the Hall mobility increased from 11.7 to 15.0 cm2 V -1 s -1. {\textcopyright} 2009 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/pssa.200881796}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-70349136686\&partnerID=40\&md5=e4e298151cf9ed7abe77db17739dd05d}, author = {Elangovan, E., Martins, R., Fortunato, E.} } @article {{\'A}guas2002387, title = {Influence of a DC grid on silane r.f. plasma properties}, journal = {Vacuum}, volume = {64}, number = {3-4}, year = {2002}, note = {

cited By 2

}, pages = {387-392}, abstract = {

In this work we show that it is possible to control the plasma regime in the region close to the substrate in r.f. silane discharges. The PECVD reactor works in a modified triode configuration, where the control over the plasma regime is performed by polarising a grid electrode, placed close to the r.f. electrode, with a DC power source. Besides that, the DC grid allows also to control the energy of the ion bombardment, because the plasma potential will be a function of the voltage (Vpol) applied to the DC grid. The silane plasma was characterised with a Langmuir probe and an impedance probe. We were able to identify three plasma regimes in the region close to the substrate: γ' regime for Vpol\<0 V; γ'-α regime for 0 V\<Vpol\<40 V; and α regime for Vpol40 V. The γ' regime is associated with a high concentration of dust particles in plasma and high electron energy (≈8eV), while the α regime is associated with a free dust plasma and low electron energy (≈2eV). The intermediate regime, γ'-α, is characterised by the presence of smaller particles (≈2-5nm) that can be beneficial for the film{\textquoteright}s properties. {\textcopyright} 2002 Elsevier Science Ltd. All rights reserved.

}, doi = {10.1016/S0042-207X(01)00343-8}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036136012\&partnerID=40\&md5=fdbc699fbf0bf7299f825847f61b230c}, author = {{\'A}guas, H., Fortunato, E., Martins, R.} } @article {Bahubalindruni2016515, title = {Influence of Channel Length Scaling on InGaZnO TFTs Characteristics: Unity Current-Gain Cutoff Frequency, Intrinsic Voltage-Gain, and On-Resistance}, journal = {Journal of Display Technology}, volume = {12}, number = {6}, year = {2016}, note = {

cited By 0

}, pages = {515-518}, abstract = {

This paper presents a study concerning the role of channel length scaling on IGZO TFT technology benchmark parameters, which are fabricated at temperatures not exceeding 180\, ^{\circ}C. The parameters under investigation are unity current-gain cutoff frequency, intrinsic voltage-gain, and on-resistance of the bottom-gate IGZO TFTs. As the channel length varies from 160 to 3 μm, the measured cutoff frequency increases from 163 {\rm kHz} to 111.5 {\rm MHz}, which is a superior value compared to the other competing low-temperature thin-film technologies, such as organic TFTs. On the other hand, for the same transistor dimensions, the measured intrinsic voltage-gain is changing from 165 to 5.3 and the on-resistance is decreasing from 1135.6 to 26.1 k{\O}mega. TFTs with smaller channel length (3 μ m) have shown a highly negative turn-on voltage and hump in the subthreshold region, which can be attributed to short channel effects. The results obtained here, together with their interpretation based on device physics, provide crucial information for accurate IC design, enabling an adequate selection of device dimensions to maximize the performance of different circuit building blocks assuring the multifunctionality demanded by system-on-panel concepts. {\textcopyright} 2005-2012 IEEE.

}, doi = {10.1109/JDT.2016.2550610}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975226429\&partnerID=40\&md5=687f1cb91fe43efa5721263d3371517a}, author = {Bahubalindruni, P.G.a , Kiazadeh, A.b , Sacchetti, A.b , Martins, J.b , Rovisco, A.b , Tavares, V.G.c , Martins, R.b , Fortunato} } @article {Wang20102674, title = {Influence of deposition pressure on N-doped ZnO films by RF magnetron sputtering}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {10}, number = {4}, year = {2010}, note = {

cited By 3

}, pages = {2674-2678}, abstract = {

N-doped ZnO films were deposited on glass substrates by RF magnetron sputtering with different deposition pressures. The samples were characterized by X-ray diffraction (XRD), atomic force morphology (AFM), X-ray photoelectron spectroscopy (XPS), Hall measurements and optical spectrophotometer. The XRD patterns confirmed that the films are polycrystalline and the influence of deposition pressure on the structural properties. AFM microstructures also authenticated the change in the size and shape of the grains as a function of deposition pressure; the root mean square (RMS) roughness has reached a maximum (10.65 nm) at 1.5 x 10 -2 mbar. XPS spectra revealed the change in the chemical composition. The amount of adsorbed oxygen and nitrogen at oxide sites has reached the maximum at 9.0 x 10 -3 mbar, where the film showed p-type conductivity. The optical transmittance spectra have indicated that the absorption edge is shifted towards the shorter wavelength at higher deposition pressure. Correspondingly, the optical band gap is increased from 2.17 to 2.80 eV. The average visible transmittance in the wavelength ranging 500-800 nm has been increased from 49\% to 82\%. Copyright {\textcopyright} 2010 American Scientific Publishers All rights reserved.

}, doi = {10.1166/jnn.2010.1401}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77954993809\&partnerID=40\&md5=29d2991a74d06de0753ea9a728a0764a}, author = {Wang, J.a , Elamurugu, E.a , Franco, N.b , Alves, E.b , Botelho Do Rego, A.M.c , Gon{\c c}alves, G.a , Martins, R.a , Fortunato, E.a} } @article {Wang2008242, title = {Influence of different carrier gases on the properties of ZnO films grown by MOCVD}, journal = {Boletin de la Sociedad Espanola de Ceramica y Vidrio}, volume = {47}, number = {4}, year = {2008}, note = {

cited By 1

}, pages = {242-244}, abstract = {

ZnO films were grown on sapphire (001) substrate by atmospheric MOCVD using diethyl zinc and tertiary butanol precursors. The influence of different carrier gases (H2 and He) on the properties was analyzed by their structural (XRD), microstructural (SEM) and compositional (SIMS) characterization. The intensity of the strongest diffraction peak from ZnO (002) plane was increased by about 2 orders of magnitude when He is used as carrier gas, indicating the significant enhancement in crystallinity. The surface of the samples grown using H2 and He carrier gases was composed of leaf-like and spherical grains respectively. Hydrogen [H] content in the film grown using H2 is higher than that using He, indicating that the [H] was influenced by the H2 carrier gas. Ultraviolet emission dominates the low temperature PL spectra. The emission from ZnO films grown using He show higher optical quality and more emission centers.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-54949098522\&partnerID=40\&md5=ff52a06346956a17a55b38ac25b766bd}, author = {Wang, J.a , Elamurugu, E.a , Sallet, V.b , Lusson, A.b , Amiri, G.b , Jomard, F.b , Martins, R.a , Fortunato, E.a} } @article {Ferreira2002591, title = {Influence of hydrogen gas dilution on the properties of silicon-doped thin films prepared by the hot-wire plasma-assisted technique}, journal = {Key Engineering Materials}, volume = {230-232}, year = {2002}, note = {

cited By 0

}, pages = {591-594}, abstract = {

P- and n-type silicon thin films have been produced using a new hot wire plasma assisted deposition process that combines the conventional plasma enhanced chemical vapor deposition and the hot wire techniques. The films were produced in the presence of different hydrogen gas flow and their optoelectronic, structural and compositional properties have been studied. The optimized optoelectronic results achieved for n-type Si:H films are conductivity at room temperature of 9.4(Ωcm)-1 and optical band gap of 2eV while for p-type SiC:H films these values are 1 {\texttimes} 10-2(Ωcm)-1 and 1.6eV, respectively. The films exhibit the required optoelectronic characteristics and compactness for device applications such as solar cells.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036434960\&partnerID=40\&md5=680eabba156e5241216387c48e230358}, author = {Ferreira, I., Vilarinho, P., Fernandes, F., Fortunato, E., Martins, R.} } @article {Pereira2005102, title = {Influence of metal induced crystallization parameters on the performance of polycrystalline silicon thin film transistors}, journal = {Thin Solid Films}, volume = {487}, number = {1-2}, year = {2005}, note = {

cited By 14

}, pages = {102-106}, abstract = {

In this work, metal induced crystallization using nickel was employed to obtain polycrystalline silicon by crystallization of amorphous films for thin film transistor applications. The devices were produced through only one lithographic process with a bottom gate configuration using a new gate dielectric consisting of a multi-layer of aluminum oxide/titanium oxide produced by atomic layer deposition. The best results were obtained for TFTs with the active layer of poly-Si crystallized for 20 h at 500 {\textdegree}C using a nickel layer of 0.5 nm where the effective mobility is 45.5 cm2 V-1 s-1. The threshold voltage, the on/off current ratio and the sub-threshold voltage are, respectively, 11.9 V, 5.55{\texttimes}104 and 2.49 V/dec. {\textcopyright} 2005 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2005.01.045}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-22944482823\&partnerID=40\&md5=c443e5f82479780a6c3c621996b04144}, author = {Pereira, L., Barquinha, P., Fortunato, E., Martins, R.} } @article {Wang20102326, title = {Influence of oxygen partial pressure on properties of N-doped ZnO films deposited by magnetron sputtering}, journal = {Transactions of Nonferrous Metals Society of China (English Edition)}, volume = {20}, number = {12}, year = {2010}, note = {

cited By 5

}, pages = {2326-2330}, abstract = {

N-doped ZnO films were radio frequency (RF) sputtered on glass substrates and studied as a function of oxygen partial pressure (OPP) ranging from 3.0{\texttimes}10-4 to 9.5{\texttimes}10-3 Pa. X-ray diffraction patters confirmed the polycrystalline nature of the deposited films. The crystalline structure is influenced by the variation of OPP. Atomic force microscopy analysis confirmed the agglomeration of the neighboring spherical grains with a sharp increase of root mean square (RMS) roughness when the OPP is increased above 1.4{\texttimes}10-3 Pa. X-ray photoelectron spectroscopy analysis revealed that the incorporation of N content into the film is decreased with the increase of OPP, noticeably N 1s XPS peaks are hardly identified at 9.5{\texttimes}10-3 Pa. The average visible transmittance (380-700 nm) is increased with the increase of OPP (from \~{}17 to 70), and the optical absorption edge shifts towards the shorter wavelength. The films deposited with low OPP (<= 3.0{\texttimes}10-4 Pa) show n-type conductivity and those deposited with high OPP (>= 9.0{\texttimes}10-4 Pa) are highly resistive (\>105 {\textperiodcentered}cm) {\textcopyright} 2010 The Nonferrous Metals Society of China.

}, doi = {10.1016/S1003-6326(10)60649-8}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-78651074162\&partnerID=40\&md5=56c6c73b6903f0e78e69ca34c4238d7c}, author = {Wang, J.-Z.a b , Elangovan, E.b , Franco, N.c , Alvese, A.c , Rego, A.d , Martins, R.b , Fortunato, E.b} } @article {Cui20081507, title = {Influence of oxygen/argon pressure ratio on the morphology, optical and electrical properties of ITO thin films deposited at room temperature}, journal = {Vacuum}, volume = {82}, number = {12}, year = {2008}, note = {

cited By 29

}, pages = {1507-1511}, abstract = {

Transparent conductive oxides (TCOs) such as indium tin oxide (ITO) thin films onto glass substrates are widely used as transparent and conductive electrodes for a variety of technological applications including flat panel displays, solar cells, smart windows, touch screens, etc. ITO films on glass and polycarbonate (PC) substrates were prepared at room temperature (RT) and at different PO2. The films were characterized in terms of the surface roughness (δ), sheet resistance, the refractive index (n) and extinction coefficient (k). The free carrier density (nc) and the carrier mobility (μ) of the ITO (In2O3:Sn) films were measured and studied. The nc and μ values vary in different ratio of oxygen partial pressure (PO2) of ITO deposition. The observed changes in the ITO film resistivity are due to the combined effect of different parameter values for nc and μ. From AFM analysis and spectra calculations, the surface roughness values of the ITO films were studied and it was observed that the δ values were lower than 15 nm. The energy band gap Eg ranges from 3.26 eV to 3.66 eV as determined from the absorption spectrum. It was observed an increase on the energy band gap as the PO2 decrease in the range of 20-2\% PO2. The Lorentz oscillator classical model has also been used to fit the ellipsometric spectra in order to obtain both refractive index n and extinction coefficient κ values. {\textcopyright} 2008 Elsevier Ltd. All rights reserved.

}, doi = {10.1016/j.vacuum.2008.03.061}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-49249130712\&partnerID=40\&md5=e05a0deef745ddd0e174da4e8a0b9e00}, author = {Cui, H.-N.a , Teixeira, V.a , Meng, L.-J.b , Martins, R.c , Fortunato, E.c} } @article {Vieira19941109, title = {Influence of photodegradation on the υτ and microstructure of pin a-Si:H devices}, journal = {Vacuum}, volume = {45}, number = {10-11}, year = {1994}, note = {

cited By 0

}, pages = {1109-1111}, abstract = {

Pin solar cells of a-Si:H were light soaked. The cell characteristics, the optoelectronic properties and the microstructure parameter, as well as the hydrogen content and density of states of the i-layer, were monitored throughout the entire light-induced degradation process and compared with the corresponding μτ product (for both carriers) inferred through steady photoconductivity and FST measurements. Results suggest a correlation between the decrease of μτ product for electrons and the increase of the fraction of hydrogen bonded on internal surfaces, showing structural changes during the degradation process. {\textcopyright} 1994.

}, doi = {10.1016/0042-207X(94)90037-X}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028516523\&partnerID=40\&md5=5a1957c989300a417d847bb77d88e115}, author = {Vieira, M., Fortunato, E., Carvalho, C., Lavareda, G., Martins, R.} } @article {Gon{\c c}alves20078562, title = {Influence of post-annealing temperature on the properties exhibited by ITO, IZO and GZO thin films}, journal = {Thin Solid Films}, volume = {515}, number = {24 SPEC. ISS.}, year = {2007}, note = {

cited By 85

}, pages = {8562-8566}, abstract = {

In this work we present a study on the effect of annealing temperatures on the structural, morphological, electrical and optical characteristics of gallium doped zinc oxide (GZO), indium zinc oxide (IZO) and indium-tin-oxide (ITO) films. GZO and IZO films were deposited at room temperature by r.f. magnetron sputtering, whereas the ITO films were commercial ones purchased from Balzers. All films were annealed at temperatures of 250 and 500~{\textdegree}C in open air for 1 h. The GZO and ITO films were polycrystalline. The amorphous structure of as-deposited IZO films becomes crystalline on high temperature annealing (500~{\textdegree}C). The sheet resistivity increased with increase in annealing temperature. GZO films showed an increase of 6 orders of magnitude. The optical transmittance and band gap of as-deposited films varied with annealing. The highest transmittance (over 95 \%) and maximum band gap (3.93~eV) have been obtained for ITO films. {\textcopyright} 2007 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2007.03.126}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34548859816\&partnerID=40\&md5=267b751d0606809c2517387c924b8574}, author = {Gon{\c c}alves, G., Elangovan, E., Barquinha, P., Pereira, L., Martins, R., Fortunato, E.} } @article {Lyubchyk20162317, title = {Influence of post-deposition annealing on electrical and optical properties of ZnO-based TCOs deposited at room temperature}, journal = {Physica Status Solidi (A) Applications and Materials Science}, volume = {213}, number = {9}, year = {2016}, note = {

cited By 0

}, pages = {2317-2328}, abstract = {

The post-deposition modification of ZnO-based transparent conductive oxides (TCOs) can be the key to produce thin films with optoelectronic properties similar to indium tin oxide (ITO), but at a much lower cost. Here, we present electro-optical results achieved for post-deposition annealing of Al{\textendash}Zn{\textendash}O (AZO), AZO:H, Ga{\textendash}Zn{\textendash}O:H (GZO:H), and Zn{\textendash}O:H (ZNO:H) thin films deposited by RF sputtering at room temperature. These studies comprise results of thermal annealing at atmospheric pressure, vacuum, forming gas, H2 and Ar atmospheres, and H2 and Ar plasmas, which lead to significant enhancement of their electro-optical properties, which are correlated to morphological and structural improvements. The post-deposition annealing leads to an enhancement in resistivity above 40\% for AZO, AZO:H, and GZO:H, reaching ρ ≈ 2.6{\textendash}3.5 {\texttimes} 10-4 Ωcm, while ZnO:H showed a lower improvement of 13\%. The averaged optical transmittance in the visible region is about 89\% for the investigated TCOs. Such results match the properties of state-of-art ITO (ρ ≈ 10-4 Ωcm and transmittance in VIS range of 90\%) employing much more earth-abundant materials. {\textcopyright} 2016 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim

}, doi = {10.1002/pssa.201532891}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982994261\&partnerID=40\&md5=6f0dcdc9c81a8b2d1f6806fc96322f3c}, author = {Lyubchyk, A., Vicente, A., Alves, P.U., Catela, B., Soule, B., Mateus, T., Mendes, M.J., {\'A}guas, H., Fortunato, E., Martins, R.} } @article {Wang20078785, title = {Influence of substrate temperature on N-doped ZnO films deposited by RF magnetron sputtering}, journal = {Thin Solid Films}, volume = {515}, number = {24 SPEC. ISS.}, year = {2007}, note = {

cited By 24

}, pages = {8785-8788}, abstract = {

Nitrogen-doped ZnO films were deposited by RF magnetron sputtering in 75\% of N2 / (Ar + N2) gas atmosphere. The influence of substrate temperature ranging from room temperature (RT) to 300~{\textdegree}C was analyzed by X-ray diffractometry (XRD), spectrophotometry, X-ray photoelectron spectroscopy (XPS), secondary-ion mass spectrometry (SIMS) and Hall measurements setup. The XRD studies confirmed the hexagonal ZnO structure and showed that the crystallinity of these films increased with increasing substrate temperature (Ts). The optical studies indicate the average visible transmittance in the wavelength ranging 500-800~nm increases with increasing Ts. A minimum transmittance (9.84\%) obtained for the films deposited at RT increased with increasing Ts to a maximum of 88.59\% at 300~{\textdegree}C (500-800~nm). Furthermore, it was understood that the band gap widens with increasing Ts from 1.99~eV (RT) to 3.30~eV (250~{\textdegree}C). Compositional analyses (XPS and SIMS) confirmed the nitrogen (N) incorporation into the ZnO films and its decreasing concentration with increasing Ts. The negative sign of Hall coefficients confirmed the n-type conducting. {\textcopyright} 2007 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2007.03.061}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34548840549\&partnerID=40\&md5=3215ee9c0dff23875eaa9f3bb4d674cb}, author = {Wang, J.a , Sallet, V.b , Jomard, F.b , Botelho do Rego, A.M.c , Elamurugu, E.a , Martins, R.a , Fortunato, E.a} } @article {Zubizarreta2016218, title = {The influence of target erosion grade in the optoelectronic properties of AZO coatings growth by magnetron sputtering}, journal = {Applied Surface Science}, volume = {380}, year = {2016}, note = {

cited By 0

}, pages = {218-222}, abstract = {

Aluminum-doped zinc oxide (AZO) transparent conductor coating has emerged as promising substitute to tin-doped indium oxide (ITO) as electrode in optoelectronic applications such as photovoltaics or light emitting diodes (LEDs). Besides its high transmission in the visible spectral region and low resistivity, AZO presents a main advantage over other candidates such as graphene, carbon nanotubes or silver nanowires; it can be deposited using the technology industrially implemented to manufacture ITO layers, the magnetron sputtering (MS). This is a productive, reliable and green manufacturing technique. But to guarantee the robustness, reproducibility and reliability of the process there are still some issues to be addressed, such as the effect and control of the target state. In this paper a thorough study of the influence of the target erosion grade in developed coatings has been performed. AZO films have been deposited from a ceramic target by RF MS. Structure, optical transmittance and electrical properties of the produced coatings have been analyzed as function of the target erosion grade. No noticeable differences have been found neither in optoelectronic properties nor in the structure of the coatings, indicating that the RF MS is a stable and consistent process through the whole life of the target. {\textcopyright} 2016 Elsevier B.V.

}, doi = {10.1016/j.apsusc.2016.01.147}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956679889\&partnerID=40\&md5=4936f4ce30d8cdc0381712bed0d3be11}, author = {Zubizarreta, C.a , G-Berasategui, E.a , Ciarsolo, I.a , Barriga, J.a , Gaspar, D.b , Martins, R.b , Fortunato, E.b} } @article {Nunes20011125, title = {Influence of the annealing conditions on the properties of ZnO thin films}, journal = {International Journal of Inorganic Materials}, volume = {3}, number = {8}, year = {2001}, note = {

cited By 52

}, pages = {1125-1128}, abstract = {

The effect of annealing treatment (in the presence of different types of atmospheres) on the performances of zinc oxide thin films (intrinsic and doped with In and Al) prepared by spray pyrolysis have been studied, with the aim to determine more adequate conditions to improve the properties of the films. The results show that the annealing treatment leads to substantial changes in the structural, electrical and optical characteristics of ZnO thin films. The most significant improvements were obtained after annealing in forming gas (reduction atmosphere) at 200{\textdegree}C during 2 h. The ZnO:In film after heat treatment was the one that exhibited the lowest resistivity (p=5.2x10-2 ωcm) and a high transmittance (T=86\%). {\textcopyright} 2001 Elsevier Science Ltd. All rights reserved.

}, doi = {10.1016/S1466-6049(01)00113-1}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035208404\&partnerID=40\&md5=2e96a43682da913cb765146a0d72fb08}, author = {Nunes, P., Fortunato, E., Martins, R.} } @article {Nunes20011129, title = {Influence of the deposition conditions on the gas sensitivity of zinc oxide thin films deposited by spray pyrolysis}, journal = {International Journal of Inorganic Materials}, volume = {3}, number = {8}, year = {2001}, note = {

cited By 50

}, pages = {1129-1131}, abstract = {

In this work we present preliminary results on the sensitivity to methane gas of zinc oxide thin films deposited by spray pyrolysis. It was found that using highly resistive (above 104 Ω cm) thin films and by performing the measurements at 200{\textdegree}C a sensitivity better than one order of magnitude was found to detect 2000 ppm of methane. A linear dependence on the sensitivity between 100 and 2000 ppm of methane was also obtained. {\textcopyright} 2001 Elsevier Science Ltd. All rights reserved.

}, doi = {10.1016/S1466-6049(01)00136-2}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035208286\&partnerID=40\&md5=9aa84ec636f148d08ce6d83cb02d346f}, author = {Nunes, P., Fortunato, E., Lopes, A., Martins, R.} } @article {Barquinha2004243, title = {Influence of the deposition conditions on the properties of titanium oxide produced by r.f. magnetron sputtering}, journal = {Materials Science in Semiconductor Processing}, volume = {7}, number = {4-6 SPEC. ISS.}, year = {2004}, note = {

cited By 13

}, pages = {243-247}, abstract = {

This work refers to the electro-optical and structural characteristics of titanium oxide (TiOx) thin films produced by radio frequency (r.f.) magnetron sputtering that present promising performances for gate dielectric applications, alone or in mixed tandem structures, such as with Al yOz films, taking advantage of its high dielectric constant. Films produced with a O2/Ar ratio between 0.1 and 0.15 present an improved stochiometry and density where the resistivity overcomes 1011 Ω cm and the fixed charge density decreases below 10 12 cm-2. The deposition pressure influences greatly the growth rate that seems to be a determinant factor dictating the films properties. {\textcopyright} 2004 Elsevier Ltd. All rights reserved.

}, doi = {10.1016/j.mssp.2004.09.116}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-9544232544\&partnerID=40\&md5=08955064e13e1daa1473051f69d00b43}, author = {Barquinha, P., Pereira, L., {\'A}guas, H., Fortunato, E., Martins, R.} } @article {Assun{\c c}{\~a}o2003401, title = {Influence of the deposition pressure on the properties of transparent and conductive ZnO:Ga thin-film produced by r.f. sputtering at room temperature}, journal = {Thin Solid Films}, volume = {427}, number = {1-2}, year = {2003}, note = {

cited By 231

}, pages = {401-405}, abstract = {

Highly conducting and transparent gallium doped zinc oxide thin films have been deposited at high growth rates by r.f. magnetron sputtering at room temperature on inexpensive soda lime glass substrates. The argon sputtering pressure was varied between 0.15 and 2.1 Pa. The lowest resistivity was 2.6 {\texttimes} 10-4 Ω cm (sheet resistance ≈6 Ω/sq. for a thickness ≈600 nm) and was obtained at an argon sputtering pressure of 0.15 Pa and a r.f. power of 175 W. The films present an overall transmittance in the visible spectra of approximately 90\%. The increase on the resistivity for higher sputtering pressures is due to a decrease of both, mobility and carrier concentration, and is associated to a change on the surface morphology. The low resistivity, accomplished with a high growth rate (290 {\r A}/min) and with a room temperature deposition enables these films deposition onto polymeric substrates for flexible optoelectronic devices. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0040-6090(02)01184-7}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037416605\&partnerID=40\&md5=63176f58a8de9bde447957a7e36cd3ba}, author = {Assun{\c c}{\~a}o, V.a , Fortunato, E.a , Marques, A.a , {\'A}guas, H.a , Ferreira, I.a , Costa, M.E.V.b , Martins, R.a} } @article {Nunes199945, title = {Influence of the doping and annealing atmosphere on zinc oxide thin films deposited by spray pyrolysis}, journal = {Vacuum}, volume = {52}, number = {1-2}, year = {1999}, note = {

cited By 58

}, pages = {45-49}, abstract = {

Undoped and doped (indium and aluminium) zinc oxide (ZnO) thin films have been prepared by spray pyrolysis, and the effect of the doping and annealing atmosphere on the electrical, optical and structural properties of the produced films has been investigated. The deposited films have a high resistivity. Annealing the films in an argon atmosphere or under vacuum leads to a substantial reduction of the electrical resistivity of the films and to an increase on the degree of cristallinity of the deposited material. The most pronounced changes were observed in the films annealed in Argon. The results also indicate that doping highly influences the electrical and structural properties of the films, which is more pronounced in the films doped with Indium. {\textcopyright} 1998 Elsevier Science Ltd. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032777967\&partnerID=40\&md5=1a1a61ffda881e1da92bb4fafd5d9fe8}, author = {Nunes, P.a , Malik, A.a , Fernandes, B.a , Fortunato, E.a , Vilarinho, P.b , Martins, R.a} } @article {Fantoni2002151, title = {Influence of the intrinsic layer characteristics on a-Si:H p-i-n solar cell performance analysed by means of a computer simulation}, journal = {Solar Energy Materials and Solar Cells}, volume = {73}, number = {2}, year = {2002}, note = {

cited By 20

}, pages = {151-162}, abstract = {

In this paper a set of one-dimensional simulations of a-Si:H p-i-n junctions under different illumination conditions and with different intrinsic layer are presented. The simulation program ASCA permits the analysis of the internal electrical behaviour of the cell allowing a comparison among the different internal configurations determined by a change in the input set. Results about the internal electric configuration will be presented and discussed outlining their influence on the current tension characteristic curve. Considerations about the drift-diffusion and the generation-recombination balance distributions, outlined by the simulation, can be used to explain the correlation between the basic device output, the i-layer characteristics (thickness and DOS), the incident radiation intensity and photon energy. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0927-0248(01)00120-9}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036605126\&partnerID=40\&md5=a4be0908ef11a190a7bc219046e9412f}, author = {Fantoni, A.a b , Viera, M.a , Martins, R.b} } @article {Raniero2005349, title = {Influence of the layer thickness and hydrogen dilution on electrical properties of large area amorphous silicon p-i-n solar cell}, journal = {Solar Energy Materials and Solar Cells}, volume = {87}, number = {1-4}, year = {2005}, note = {

cited By 3

}, pages = {349-355}, abstract = {

The aim of this work is to present data concerning the optimization of performances of a large area amorphous silicon p-i-n solar cell (30{\texttimes}40 cm2) deposited by plasma enhanced chemical vapour deposition (PECVD) at 27.12 MHz. In this work the solar cell was split into small areas of 0.126 cm2, aiming to study the device performance uniformity, where emphasis was put on the role of the n-layer thickness. The solar cells were studied through the spectral response behaviour in the 400-750 nm range as well as by the behaviour of the AC impedance. Solar cells with fill factor of 0.58, open circuit voltage of 0.83 V, short circuit current density of 17.14 mA/cm2 and an efficiency of 8\% were obtained at growth rates higher than 0.3 nm/s. {\textcopyright} 2004 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.solmat.2004.08.014}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17644411994\&partnerID=40\&md5=24b3843ee56a6e1dcd85bdee2d2a7b67}, author = {Raniero, L., Martins, N., Canhola, P., Zhang, S., Pereira, S., Ferreira, I., Fortunato, E., Martins, R.} } @article {Gaspar2013, title = {Influence of the layer thickness in plasmonic gold nanoparticles produced by thermal evaporation}, journal = {Scientific Reports}, volume = {3}, year = {2013}, note = {

cited By 23

}, abstract = {

Metallic nanoparticles (NPs) have received recently considerable interest of photonic and photovoltaic communities. In this work, we report the optoelectronic properties of gold NPs (Au-NPs) obtained by depositing very thin gold layers on glass substrates through thermal evaporation electron-beam assisted process. The effect of mass thickness of the layer was evaluated. The polycrystalline Au-NPs, with grain sizes of 14 and 19 nm tend to be elongated in one direction as the mass thickness increase. A 2 nm layer deposited at 250 C led to the formation of Au-NPs with 10-20 nm average size, obtained by SEM images, while for a 5 nm layer the wide size elongates from 25 to 150 nm with a mean at 75 nm. In the near infrared region was observed an absorption enhancement of amorphous silicon films deposited onto the Au-NPs layers with a corresponding increase in the PL peak for the same wavelength region.

}, doi = {10.1038/srep01469}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84876533482\&partnerID=40\&md5=38d58ebe9cddcbd08fe83d79ea94226f}, author = {Gaspar, D.a , Pimentel, A.C.a , Mateus, T.a , Leit{\~a}o, J.P.b , Soares, J.b , Falc{\~a}o, B.P.b , Ara{\'u}jo, A.a , Vicente, A.a , Filonov} } @article {Pereira2005210, title = {Influence of the oxygen/argon ratio on the properties of sputtered hafnium oxide}, journal = {Materials Science and Engineering B: Solid-State Materials for Advanced Technology}, volume = {118}, number = {1-3}, year = {2005}, note = {

cited By 44

}, pages = {210-213}, abstract = {

In this work we have focused our attention on the role of the gas mixture (O2/Ar) used during HfO2 thin film processing by r.f. magnetron sputtering, to produce dielectrics with suitable characteristics to be used as gate dielectric. Increasing the O2/Ar ratio from 0 to 0.2, the films properties (optical gap, permittivity, resistivity and compactness) are improved. At these conditions, films with a band gap around 5 eV were produced, indicating a good stoichiometry. Also the flat band voltage has a reduction of almost three times indicating also a reduction of the same order on the fixed charge density at the semiconductor-insulator interface. The dielectric constant is around 16 which is very good, since the surface of the silicon where the HfO2 films were deposited contains a SiO 2 layer of about 3 nm that gives an effective dielectric constant above 20, close to the HfO2 stoichiometric value (\~{}25). Further increase on the O2/Ar ratio does not produce significant improvements. {\textcopyright} 2004 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.mseb.2004.12.030}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-15344339242\&partnerID=40\&md5=dc4fa9092a6a0017715d3aedf3135a4f}, author = {Pereira, L., Barquinha, P., Fortunato, E., Martins, R.} } @article {{\'A}guas2002583, title = {Influence of the plasma regime on the structural, optical and transport properties of a-Si:H thin films}, journal = {Key Engineering Materials}, volume = {230-232}, year = {2002}, note = {

cited By 0

}, pages = {583-586}, abstract = {

In this work we show that it is possible to control the plasma species present near the substrate surface, from what is usually associated with an α regime (a plasma free of particles) to a γ{\textquoteright} regime (a plasma where particles are present) and simultaneously control the energy of the ions striking the substrate during a-Si:H deposition from a silane glow discharge in a modified triode (MT) type PECVD reactor, where a DC mesh electrode biased with Vpol is located in front of the r.f electrode. The presence of large particles in the plasma leads to the deposition of the films with the poorest optoelectronic properties. When the particle size in the plasma decrease the film properties improve, but, when particles are no longer present in the plasma region close to the substrate, like in a α like regime, the properties of the films deteriorate again. The results show that the best transport properties are achieved for the films deposited in the α-γ{\textquoteright} transition regime corresponding to 0V\<Vpol\<51V. Under this condition the films present a dark conductivity, σ d ≈ 10-11 (Ωcm)-1, photosensitivity, S ≈ 107, activation energy, ΔE ≈ 0.9 eV, hydrogen content, CH ≈ 10\%, factor of microstructure, R ≈ 0.085 and an optical gap, Eop ≈ 1.77 eV.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036436562\&partnerID=40\&md5=2732b40d068ebcd3cc9670443d94695e}, author = {{\'A}guas, H., Martins, R., Fortunato, E.} } @article {{\'A}guas200111, title = {Influence of the plasma regime on the structural, optical, electrical and morphological properties of a-Si:H thin films}, journal = {Materials Science Forum}, volume = {382}, year = {2001}, note = {

cited By 3

}, pages = {11-20}, abstract = {

{In this work we report how it is possible to control the plasma regime near the substrate surface, from predominantly α to predominantly γ{\textquoteright}, passing trough and intermediate α-γ{\textquoteright} regime, and simultaneously control the energy of the ions striking the substrate during a-Si:H deposition from a silane glow discharge in a modified triode type PECVD reactor. To do so, we apply a DC voltage (Vpol to a set of grids placed in front of the r.f. electrode and by doing this, we control the energy of the ions striking the substrate during the film{\textquoteright}s growth and the plasma regime near the substrate. Under a plasma of the γ{\textquoteright} regime, the surface roughness is high and the films are poorly compact. In the α-γ{\textquoteright} regime, the ion bombardment is moderate and the films are highly smooth and compact. In the α regime the ion bombardment is higher and so the films can become more compact but the surface roughness increases and the electrical properties deteriorate. The results achieved show that the best transport properties are achieved for the films deposited in the α-γ{\textquoteright} regime corresponding to a Vpol of 38 V. Under this condition the films presented a dark conductivity, σd = 6.2{\texttimes}10-12 (Ωcm)-1, activation energy, ΔE ≈ 0.9 eV, hydrogen content

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035682789\&partnerID=40\&md5=91718c4ebd3a1dc5162c1fafa64aea93}, author = {{\'A}guas, H., Martins, R., Nunes, Y., Maneira, M., Fortunato, E.} } @article {Nunes2001277, title = {Influence of the post-treatment on the properties of ZnO thin films}, journal = {Thin Solid Films}, volume = {383}, number = {1-2}, year = {2001}, note = {

cited By 157

}, pages = {277-280}, abstract = {

In this work a study of the influence of the annealing treatment (atmosphere and temperature) on the properties of zinc oxide thin films (intrinsic and doped with indium and aluminum) prepared by spray pyrolysis is presented. The result shows that the type of atmosphere (reduction or oxidant) has an important role in the changes observed in the structural, electrical and optical properties of the ZnO thin films. The ZnO thin film doped with indium, presents the lowest resistivity (ρ = 5.8{\texttimes}10-3 Ωcm) associated to a high transmittance (T = 86\%), characteristics required for application on optoelectronic devices.

}, doi = {10.1016/S0040-6090(00)01577-7}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035246835\&partnerID=40\&md5=b6fef2a67cc9d2aa0f45b48be8a02d4e}, author = {Nunes, P., Fortunato, E., Martins, R.} } @article {Ba{\'\i}a2001244, title = {Influence of the process parameters on structural and electrical properties of r.f. magnetron sputtering ITO films}, journal = {Thin Solid Films}, volume = {383}, number = {1-2}, year = {2001}, note = {

cited By 26

}, pages = {244-247}, abstract = {

This paper presents results of the role of the oxygen concentration (CO) and the deposition pressure (pd) on structural and electrical properties of indium tin oxide films produced by r.f. magnetron sputtering. The films were annealed in air, followed by a reannealed stage in hydrogen, aiming to improve the film{\textquoteright}s transparency and conductivity. The results achieved show that the films texture grain size, structure and compactness is more influenced by CO than by pd, the same does not happen with the electrical properties.

}, doi = {10.1016/S0040-6090(00)01589-3}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-2942746184\&partnerID=40\&md5=bfd887999ac9907260e9597310027833}, author = {Ba{\'\i}a, I., Fernandes, B., Nunes, P., Quintela, M., Martins, R.} } @article {Nedev2004108, title = {Influence of the rapid thermal annealing on the properties of thin a-Si films}, journal = {Materials Science Forum}, volume = {455-456}, year = {2004}, note = {

cited By 0

}, pages = {108-111}, abstract = {

The variation of the structure, morphology and the electrical properties of thin amorphous silicon films caused by Rapid Thermal Annealing is studied. The films annealed at 1200{\textdegree}C for 2 minutes change their structure to polycrystalline and as a result their resistivity decreases by 4 orders of magnitude. Due to the small thickness of the as deposited amorphous silicon the obtained poly-Si is strongly irregular and has many discontinuities in its texture.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-3142658011\&partnerID=40\&md5=a51bb9a36b0e33a7e17d6cdc2ea5c9e1}, author = {Nedev, N.a b , Beshkov, G.a , Fortunato, E.b , Georgiev, S.S.a b , Ivanov, T.a , Raniero, L.b , Zhang, S.b c , Martins, R.b} } @article {Wang20078780, title = {Influence of the reactive N2 gas flow on the properties of rf-sputtered ZnO thin films}, journal = {Thin Solid Films}, volume = {515}, number = {24 SPEC. ISS.}, year = {2007}, note = {

cited By 25

}, pages = {8780-8784}, abstract = {

Nitrogen (N)-doped ZnO thin films were RF sputtered with different N2 volume (ranging from 10\% to 100\%) on sapphire (001) substrates. The influence of N2 vol.\% on the properties of ZnO films was analyzed by various characterization techniques. The X-ray diffraction studies showed that the films grow along the preferential (002) crystallographic plane and the crystallinity varied with varying N2 vol.\%. The films sputtered with 25~vol.\% N2 showed better crystallinity. The transmittance was decreased with increasing N2 volume until 25\% and was almost constant above 25\%. A maximum optical band gap (2.08~eV) obtained for 10~vol.\% N2 decreased with increasing N2 volume to reach a minimum of 1.53~eV at 100\%. The compositional analysis confirmed the incorporation of N into ZnO films, and its concentration increased with increasing N2 volume to reach a maximum of \~{} 3.7 {\texttimes} 1021~atom/cm3 at 75\% but then decreased slightly to 3.42 {\texttimes} 1021~atoms/cm3. The sign of Hall coefficient confirmed that the films sputtered with <= 25~vol.\% N2 possess p-type conductivity which changes to n-type for \> 25~vol.\% N2. {\textcopyright} 2007 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2007.03.062}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34548827052\&partnerID=40\&md5=f043056a98a20b71a1e8c6dd5c9d9c9d}, author = {Wang, J.a , Sallet, V.b , Jomard, F.b , Botelho do Rego, A.M.c , Elamurugu, E.a , Martins, R.a , Fortunato, E.a} } @article {Wang20061527, title = {Influence of the self-buffer layer on ZnO film grown by atmospheric metal organic chemical vapor deposition}, journal = {Thin Solid Films}, volume = {515}, number = {4}, year = {2006}, note = {

cited By 2

}, pages = {1527-1531}, abstract = {

ZnO films with and without a self-buffer layer were grown on c-plane sapphire substrates by atmospheric metal organic chemical vapor deposition. The influence of the buffer layer thickness, annealing temperature and annealing time on ZnO films has been investigated. The full width at half maximum of the ω-rocking curve of the optimized self-buffer layer sample is only 395~arc~sec. Its surface is composed of regular columnar hexagons. After the buffer layer was introduced, the A1 longitudinal mode peak at 576~cm- 1, related to the defects, disappears in Raman spectra. For the photoluminescence, besides the strong donor binding exciton peak at 3.3564~eV, an ionized donor binding exciton and a free exciton peak is respectively observed at 3.3673 and 3.3756~eV at the high-energy side in the spectrum of the sample with the buffer layer. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2006.04.027}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33750842088\&partnerID=40\&md5=00eda684de22b4e898c7bcaecca38756}, author = {Wang, J.c , Sallet, V.a , Amiri, G.a , Rommelluere, J.-F.a , Lusson, A.a , Lewis, J.E.b , Galtier, P.a , Fortunato, E.c , Martin} } @article {Barquinha20061749, title = {Influence of the semiconductor thickness on the electrical properties of transparent TFTs based on indium zinc oxide}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 148

}, pages = {1749-1752}, abstract = {

Multicomponent amorphous oxides are starting to emerge as a class of appealing semiconductor materials for application in transparent electronics. In this work, a high performance bottom-gate n-type transparent thin-film transistors are reported, being the discussion primarily focused on the influence of the indium zinc oxide active layer thickness on the properties of the devices. For this purpose, transparent transistors with active layer thicknesses ranging from 15 nm to 60 nm were produced at room temperature using rf magnetron sputtering. Optical transmittance data in the visible range reveals average transmittance higher than 80\%, including the glass substrate. The devices work in the enhancement mode and exhibit excellent saturation drain currents. On-off ratios above 107 are achieved, but this value tends to be lower for devices with thicker semiconductor films, as a result of the decrease in the resistance of the channel region with increasing thickness. Channel mobilities are also quite respectable, with some devices presenting values around 40 cm2/V s, even without any annealing or other post-deposition improvement processes. Concerning the evolution of threshold voltage with the thickness, this work shows that it increases from about 3 V in thicker films up to about 10 V in the thinnest ones. The interesting electrical properties obtained and the versatility arising from the fact that it is possible to modify them changing only the thickness of the semiconductor makes this new transparent transistors quite promising for future transparent ICs. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2006.01.067}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33744780986\&partnerID=40\&md5=8525275495b8a98612da95e1efa30042}, author = {Barquinha, P., Pimentel, A., Marques, A., Pereira, L., Martins, R., Fortunato, E.} } @article {Fortunato2002610, title = {Influence of the strain on the electrical resistance of zinc oxide doped thin film deposited on polymer substrates}, journal = {Advanced Engineering Materials}, volume = {4}, number = {8}, year = {2002}, note = {

cited By 21

}, pages = {610-612}, abstract = {

Tensile tests were performed on PET films coated with Al doped zinc oxide films by RF magnetron sputtering. During the tensile elongation, the electrical resistance of the oxide was evaluated in situ. The results indicate that the increase in the electrical resistance is related to the crack debsity and crack width, which also depends on the film thickness.

}, doi = {10.1002/1527-2648(20020806)4:8<610::AID-ADEM610>3.0.CO;2-1}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036671534\&partnerID=40\&md5=c9a1a7d9d7e3b9a0f6321b7986abdb2c}, author = {Fortunato, E.a , Nunes, P.a , Marques, A.a , Costa, D.a , {\'A}guas, H.a , Ferreira, I.a , Costa, M.E.V.b , Godinho, M.H.a , Almeida} } @article {Ara{\'u}jo201618235, title = {Influence of the Substrate on the Morphology of Self-Assembled Silver Nanoparticles by Rapid Thermal Annealing}, journal = {Journal of Physical Chemistry C}, volume = {120}, number = {32}, year = {2016}, note = {

cited By 0

}, pages = {18235-18242}, abstract = {

Metal nanoparticles are of great interest for light trapping in photovoltaics. They are usually incorporated in the rear electrode of solar cells, providing strong light scattering at their surface plasmon resonances. In most cases, the nanoparticles are self-assembled by solid-state dewetting over a transparent conductive oxide (TCO) layer incorporated in the cell{\textquoteright}s rear electrode. Up to now, this process has been optimized mainly by tuning the thermal annealing parameters responsible for dewetting, or the thickness of the precursor metallic layer; but little attention has been paid to the influence of the underlying TCO layer properties on the morphology of the nanoparticles formed, which is the focus of the present article. This work investigates Ag nanoparticles structures produced on distinct surfaces by a simple, fast and highly reproducible method employing rapid thermal annealing. The results indicate that both the thermal conductivity and surface roughness of the TCO layer play a determinant role on the morphology of the nanostructures formed. This is of particular relevance, since we show in the study performed that the parasitic absorption of these Ag nanostructures is reduced, while the scattering is enhanced when the Ag nanostructures are formed on TCO layers with the highest conductivity and the lowest surface roughness (\~{}1 nm). These results unveil novel possibilities for the improvement of plasmonic nanostructures fabricated by thermal dewetting, via the careful adjustment of the physical properties of the underlying surface. {\textcopyright} 2016 American Chemical Society.

}, doi = {10.1021/acs.jpcc.6b04283}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983523367\&partnerID=40\&md5=04a6d23c9f55b5f3583cd9d3c1d6c372}, author = {Ara{\'u}jo, A., Mendes, M.J., Mateus, T., Vicente, A., Nunes, D., Calmeiro, T., Fortunato, E., {\'A}guas, H., Martins, R.} } @article {Barquinha2006319, title = {Influence of time, light and temperature on the electrical properties of zinc oxide TFTs}, journal = {Superlattices and Microstructures}, volume = {39}, number = {1-4}, year = {2006}, note = {

cited By 26

}, pages = {319-327}, abstract = {

In this work we present a study concerning the influence of some of the most important external factors on the electrical properties of transparent thin-film transistors (TFTs), using zinc oxide produced at room temperature as the semiconductor material. Electrical characterization performed sixteen months after the production of the devices showed a decrease in the on/off ratio from 8{\texttimes}105 to 1{\texttimes}105, mainly due to the increase of the off-current. We also observed a small increase in the saturation mobility, a decrease in the threshold voltage and an increase in the gate voltage swing (by factors of about 1.2, 0.9 and 1.6, respectively). Exposure to ambient light does not have a noticeable effect on the electrical properties, which is an important point as regards the application of these devices in active matrix displays. Some variation of the electrical properties was only detectable under intense white light radiation. In order to evaluate the temperature effect on the TFTs, they were also characterized at 90 {\textdegree}C. At this temperature we noticed that the off-current increased more than two times, and the other electrical properties had a small variation, returning to their initial values after cooling, meaning that the process is totally reversible. {\textcopyright} 2005 Elsevier Ltd. All rights reserved.

}, doi = {10.1016/j.spmi.2005.08.057}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-29344450647\&partnerID=40\&md5=bdc9f018528c06fc9760fe0d59bc1ccf}, author = {Barquinha, P., Fortunato, E., Gon{\c c}alves, A., Pimentel, A., Marques, A., Pereira, L., Martins, R.} } @article {Bahubalindruni2016419, title = {InGaZnO thin-film-transistor-based four-quadrant high-gain analog multiplier on glass}, journal = {IEEE Electron Device Letters}, volume = {37}, number = {4}, year = {2016}, note = {

cited By 0

}, pages = {419-421}, abstract = {

This letter presents a novel high-gain four-quadrant analog multiplier using only n-type enhancement indium- gallium-zinc-oxide thin-film-transistors. The proposed circuit improves the gain by using an active load with positive feedback. A Gilbert cell with a diode-connected load is also presented for comparison purposes. Both circuits were fabricated on glass at low temperature (200 {\textdegree}C) and were successfully characterized at room temperature under normal ambient conditions, with a power supply of 15 V and 4-pF capacitive load. The novel circuit has shown a gain improvement of 7.2 dB over the Gilbert cell with the diode-connected load. Static linearity response, total harmonic distortion, frequency response, and power consumption are reported. This circuit is an important signal processing building block in large-area sensing and readout systems, specially if data communication is involved. {\textcopyright} 2016 IEEE.

}, doi = {10.1109/LED.2016.2535469}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84963839212\&partnerID=40\&md5=2d6c653ce01a9594eae321daaf5151c2}, author = {Bahubalindruni, P.G.a , Tavares, V.G.b , Borme, J.c , De Oliveira, P.G.b , Martins, R.a , Fortunato, E.a , Barquinha, P.a} } @article {Bernacka-Wojcik20101229, title = {Inkjet printed and "doctor blade" TiO2 photodetectors for DNA biosensors}, journal = {Biosensors and Bioelectronics}, volume = {25}, number = {5}, year = {2010}, note = {

cited By 28

}, pages = {1229-1234}, abstract = {

A dye sensitized TiO2 photodetector has been integrated with a DNA detection method based on non-cross-linking hybridization of DNA-functionalized gold nanoparticles, resulting in a disposable colorimetric biosensor. We present a new approach for the fabrication of dye sensitized TiO2 photodetectors by an inkjet printing technique-a non-contact digital, additive, no mask and no vacuum patterning method, ideal for cost efficient mass production. The developed biosensor was compared against a dye sensitized photodetector fabricated by the traditional "doctor blade" method. Detection of gold nanoparticle aggregation was possible for concentrations as low as 1.0 nM for the "doctor blade" system, and 1.5 nM for the inkjet printed photodetector. The demonstrated sensitivity limits of developed biosensors are comparable to those of spectrophotometric techniques (1.0 nM). Our results show that a difference higher than 17\% by traditional photodetector and 6\% by inkjet printed in the photoresponses for the complementary and non-complementary gold nanoprobe assays could be attained for a specific DNA sequence from Mycobacterium tuberculosis, the etiologic agent of human tuberculosis. The decrease of costs associated with molecular diagnostic provided by a platform such as the one presented here may prove of paramount importance in developing countries. {\textcopyright} 2009 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.bios.2009.09.027}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-72149094849\&partnerID=40\&md5=5a7a74e727bbc691efc26e51a326e84d}, author = {Bernacka-Wojcik, I.a , Senadeera, R.a b , Wojcik, P.J.a , Silva, L.B.a , Doria, G.c d , Baptista, P.c , Aguas, H.a , Fortunato,} } @article {Bernacka-Wojcik2016208, title = {Inkjet printed highly porous TiO2 films for improved electrical properties of photoanode}, journal = {Journal of Colloid and Interface Science}, volume = {465}, year = {2016}, note = {

cited By 1

}, pages = {208-214}, abstract = {

The aim of presented work is to show the improvements obtained in the properties of TiO2 films for dye sensitized solar cells fabricated by inkjet printing using an innovative methodology. We describe the development and properties of TiO2-based inks used in a lab-scale printer, testing various commercial TiO2 pastes. The porosity of the deposited inkjet printed TiO2 films is much higher than using the conventional "doctor blade" deposition technique, as the ink solvent evaporates during the droplet fly from the nozzle to the substrate due to its picoliter volume and the applied heating of a printing stage (70{\textdegree}C). Thanks to higher surface area, the dye sensitized solar cells incorporating inkjet printed TiO2 film gave higher efficiencies (ηmax≈3.06\%) than the more compact films obtained by the "doctor blade" method (ηmax≈2.56\%). Furthermore, electrochemical analysis indicates that for whole tested thickness range, the inkjet printed layers have higher effective electron diffusion length indicating their better transport properties. {\textcopyright} 2015 Elsevier Inc..

}, doi = {10.1016/j.jcis.2015.11.070}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949845705\&partnerID=40\&md5=dfd09ca0f5ea733f88ccc7526af80904}, author = {Bernacka-Wojcik, I.a b , Wojcik, P.J.a b , Aguas, H.a , Fortunato, E.a , Martins, R.a} } @article {Olziersky2010, title = {Insight on the SU-8 resist as passivation layer for transparent Ga 2 O3 - In2 O3-ZnO thin-film transistors}, journal = {Journal of Applied Physics}, volume = {108}, number = {6}, year = {2010}, note = {

cited By 32

}, abstract = {

{A nonvacuum and low temperature process for passivating transparent metal oxides based thin-film transistors is presented. This process uses the epoxy-based SU-8 resist which prevents device degradation against environmental conditions, vacuum or sputtering surface damage. The incorporation of SU-8 as a passivation layer is based on the ability of this polymer to provide features with high mechanical and chemical stability. With this approach, lithography is performed to pattern the resist over the active area of the device in order to form the passivation layer. The resulting transistors demonstrate very good electrical characteristics, such as μFE =61 cm2 /V s

}, doi = {10.1063/1.3477192}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77957740514\&partnerID=40\&md5=c035abb8be52b3a1285c1065b6c55e3c}, author = {Olziersky, A.a , Barquinha, P.b , Vil̀, A.a , Pereira, L.b , Gonalves, G.b , Fortunato, E.b , Martins, R.b , Morante, J.R.a c} } @article {Martins200613, title = {Insights on amorphous silicon nip and MIS 3D position sensitive detectors}, journal = {Materials Science Forum}, volume = {514-516}, number = {PART 1}, year = {2006}, note = {

cited By 2

}, pages = {13-17}, abstract = {

This work aims to report results of the spatial and frequency optical detection limits of integrated arrays of 32 one-dimensional amorphous silicon thin film position sensitive detectors with nip or MIS structure, under continuous and pulsed laser operation conditions. The arrays occupy a total active area of 45 mm2 and have a plane image resolution better than 15 μm with a cut-off frequency of about 6.8 kHz. The non-linearity of the array components varies with the frequency, being about 1.6\% for 200 Hz and about 4\% for the cut-off frequency (6.8 kHz).

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-37849015836\&partnerID=40\&md5=b739843d5eb7fa40c0b28a3354336ce4}, author = {Martins, R.a , Costa, D.a , {\'A}guas, H.a , Soares, F.a , Marques, A.a b , Ferreira, I.a , Borges, P.b , Pereira, S.b , Raniero, L.} } @article {Martins19839, title = {The interpretation of the electric and optical properties of a-Si:H films produced by rf glow discharge through dark conductivity, photoconductivity and pulse controlled capacitance-voltage measurements}, journal = {Journal of Non-Crystalline Solids}, volume = {57}, number = {1}, year = {1983}, note = {

cited By 0

}, pages = {9-22}, abstract = {

This paper deals with the interpretation of transport properties of amorphous silicon hydrogenated films (a-Si:H) through dark conductivity, photoconductivity and pulse controlled capacitance-voltage measurements. a-Si:H films were produced by rf glow discharge coupled either inductively or capacitively to a 3\% SiH4/Ar mixture at different crossed electromagnetic static fields. The data concerned with the dark activation energy, photoactivation energy, variation of the density of localized states and photosensitivity, (σph/σd)25{\textdegree}C, of a-Si:H films can account for their optoelectronic properties which are strongly dependent on the deposition parameters. We also observed that crossed electromagnetic static fields applied during film formation influences hydrogen incorporation in a different manner than previously proposed. {\textcopyright} 1983.

}, doi = {10.1016/0022-3093(83)90404-0}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0020807008\&partnerID=40\&md5=1807d96fc8f9c108f34290a029959a49}, author = {Martins, R., Dias, A.G., Guimar{\~a}es, L.} } @article {Martins19962143, title = {Interpretation of the static and dynamic characteristics of 1-D thin film position sensitive detectors based on a-Si:H p-i-n Diodes}, journal = {IEEE Transactions on Electron Devices}, volume = {43}, number = {12}, year = {1996}, note = {

cited By 7

}, pages = {2143-2152}, abstract = {

In this work, we present a model to interpret the steady-state and the dynamic detection limits of 1-D Thin Film Position Sensitive Detectors (1-D TFPSD) based on p-i-n a-Si:H devices. From this, an equivalent electric circuit is derived and the predicted values are compared with the experimental results obtained in 1-D TFPSD devices, with different sizes. The model is also able to determine the device characteristics that influence the spatial limits and the response time of the device. {\textcopyright} 1996 IEEE.

}, doi = {10.1109/16.544385}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030379338\&partnerID=40\&md5=ccecaf09a3766c27fcb1cd1beab43793}, author = {Martins, R.F.P., Fortunato, E.M.C.} } @article {Jin2016, title = {Interpreting anomalies observed in oxide semiconductor TFTs under negative and positive bias stress}, journal = {AIP Advances}, volume = {6}, number = {8}, year = {2016}, note = {

cited By 0

}, abstract = {

Oxide semiconductor thin-film transistors can show anomalous behavior under bias stress. Two types of anomalies are discussed in this paper. The first is the shift in threshold voltage (VTH) in a direction opposite to the applied bias stress, and highly dependent on gate dielectric material. We attribute this to charge trapping/detrapping and charge migration within the gate dielectric. We emphasize the fundamental difference between trapping/detrapping events occurring at the semiconductor/dielectric interface and those occurring at gate/dielectric interface, and show that charge migration is essential to explain the first anomaly. We model charge migration in terms of the non-instantaneous polarization density. The second type of anomaly is negative VTH shift under high positive bias stress, with logarithmic evolution in time. This can be argued as electron-donating reactions involving H2O molecules or derived species, with a reaction rate exponentially accelerated by positive gate bias and exponentially decreased by the number of reactions already occurred. {\textcopyright} 2016 Author(s).

}, doi = {10.1063/1.4962151}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984677284\&partnerID=40\&md5=f3cff1341caca5041c8a817faa91e99f}, author = {Jin, J.W.a , Nathan, A.b , Barquinha, P.c , Pereira, L.c , Fortunato, E.c , Martins, R.c , Cobb, B.d} } @article {Wang2009813, title = {Intrinsic P type ZNO films deposited by RF magnetron sputtering}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {9}, number = {2}, year = {2009}, note = {

cited By 6

}, pages = {813-816}, abstract = {

ZnO films were deposited on c-plane sapphire substrates in Ar atmosphere by ii magnetron sputtering and were post-annealed at 400{\textdegree}C in green gas (95\% N2 + 5\% H2). The properties of the as-grown and annealed films have been characterized by X-ray diffraction (XRD), Rutherford backscattering (RBS), elastic recoil detection analysis (ERDA), Hall measurement and photoluminescence spectra. XRD studies confirmed the variation in strain and an improvement in crystallinity. From RBS and ERDA analysis, the presence of H atoms on the surface of the as-grown ZnO films was evidenced. Annealing in green gas increased the amount of H in the film. Compared with the as-grown films, the ultra exciting intensity obviously decreases in the annealed films and new optical active centres in the blue/violet (~3.0 eV) and red (~1.9) regions are emerged in the PL spectrum. The positive sign of Hall coefficient confirmed the low (-type conductivity in the as grown films, which was improved after annealing. However, the (-type conductivity was not stable, especially for the annealed sample it changes from ( type to n type after 9 days. Copyright {\textcopyright} 2009 American Scientific Publishers All rights reserved.

}, doi = {10.1166/jnn.2009.C030}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67349240322\&partnerID=40\&md5=8ac1b9200580d42fb22574ce9cd70357}, author = {Wang, J.a , Martins, R.a , Barradas, N.P.c , Alves, E.c , Monteiro, T.b , Peres, M.b , Elamurugu, E.a , Fortunato, E.a} } @article {{\'A}guas20061787, title = {Investigation of a-Si:H 1D MIS position sensitive detectors for application in 3D sensors}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 4

}, pages = {1787-1791}, abstract = {

This paper presents the results achieved in optimized 1D position sensitive detectors (PSD) using a metal-insulator-semiconductor (MIS) structure and different length to width ratios, in order to determine the optimal geometrical factor for the desired 3D integration. The results show that the optimized MIS PSD produced, exhibited linearity errors as low as 0.8\% and sensitivities of 32 mV/cm, for a 5 mW spot beam intensity at a wavelength of 532 nm. The sensors can achieve a longitudinal spatial resolution of 1.25 μm (estimated by modulation transfer function calculation), while the transverse resolution depends on the minimum width used for each sensor. The calculated Jones parameter of the sensors is higher than 1011 J, with a fall-off parameter of 0.012 cm-1, indicating a high signal to noise detection ratio. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2005.09.042}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33745444243\&partnerID=40\&md5=5d54f4d3e8343e8716f73a14d7bd8650}, author = {{\'A}guas, H., Pereira, L., Raniero, L., Costa, D., Fortunato, E., Martins, R.} } @article {Prabakaran20082610, title = {Investigation of hydrocarbon coated porous silicon using PECVD technique to detect CO2 gas}, journal = {Journal of Non-Crystalline Solids}, volume = {354}, number = {19-25}, year = {2008}, note = {

cited By 3

}, pages = {2610-2614}, abstract = {

In the present work, we investigate the influence of hydrocarbon (CHx) thin film coating on porous silicon (PS) by plasma enhanced chemical vapor deposition (PECVD) technique to detect CO2 gas. The fabricated CHx/PS heterojunction device shows up to one and two orders of magnitude enhancement in current under CO2 gas exposure. FTIR spectroscopy measurements reveal a remarkable structural modification of the CHx/PS device during CO2 gas exposure. Further, the enhancement of CHx related absorbance bands by a factor 6.2 for the CHx/PS specimen in comparison with PS confirm the good quality of the deposited CHx thin films. {\textcopyright} 2007 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2007.10.101}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-43049117472\&partnerID=40\&md5=70ff473fea519df9080a1b80d84a9233}, author = {Prabakaran, R., Silva, L., Fortunato, E., Martins, R., Ferreira, I.} } @article {Gokulakrishnan2012589, title = {Investigation of O 7+ swift heavy ion irradiation on molybdenum doped indium oxide thin films}, journal = {Radiation Physics and Chemistry}, volume = {81}, number = {6}, year = {2012}, note = {

cited By 6

}, pages = {589-593}, abstract = {

Molybdenum (0.5at\%) doped indium oxide thin films deposited by spray pyrolysis technique were irradiated by 100MeV O 7+ ions with different fluences of 5{\texttimes}10 11, 1{\texttimes}10 12 and 1{\texttimes}10 13ions/cm 2. Intensity of (222) peak of the pristine film was decreased with increase in the ion fluence. Films irradiated with the maximum ion fluence of 1{\texttimes}10 13ions/cm 2 showed a fraction of amorphous nature. The surface microstructures on the surface of the film showed that increase in ion fluence decreases the grain size. Mobility of the pristine molybdenum doped indium oxide films was decreased from ~122 to 48cm 2/Vs with increasing ion fluence. Among the irradiated films the film irradiated with the ion fluence of 5{\texttimes}10 11ions/cm 2 showed relatively low resistivity of 6.7{\texttimes}10 -4Ωcm with the mobility of 75cm 2/Vs. The average transmittance of the as-deposited IMO film is decreased from 89\% to 81\% due to irradiation with the fluence of 5{\texttimes}10 11ions/cm 2. {\textcopyright} 2012 Elsevier Ltd.

}, doi = {10.1016/j.radphyschem.2012.02.037}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84859705759\&partnerID=40\&md5=34854fc0c82b187eddac1eecafa59fa3}, author = {Gokulakrishnan, V.a , Parthiban, S.a c , Elangovan, E.c , Jeganathan, K.b , Kanjilal, D.d , Asokan, K.d , Martins, R.c , Fortuna} } @article {Martins1998144, title = {Investigation of the amorphous to microcrystalline phase transition of thin film silicon produced by PECVD}, journal = {Thin Solid Films}, volume = {317}, number = {1-2}, year = {1998}, note = {

cited By 9

}, pages = {144-148}, abstract = {

We have deposited by Plasma Enhanced Chemical Vapour Deposition phosphorus doped amorphous and microcrystalline silicon films, as a function of the RF power (10-300 W), using a PH3/(SiH4 + H2 + He)mixture. It was found that films microcrystallization occurs for powers above 130 W, where a clear phase transition occurs. The microcrystalline films produced present high dark conductivities and optical band gaps, where the crystalline volume fraction is above 25\%, as revealed by micro Raman spectroscopy. The Hall mobility have been also determined for amorphous and microcrystalline films, as a function of temperature, in the range 280-340 K. The data show that for the microcrystalline films the conduction is mainly in the extended states of the microcrystals, confirming also the double sign anomaly. That is, for n-type films, the sign is positive for the amorphous case while it is negative for the microcrystalline case. {\textcopyright} 1998 Elsevier Science S.A.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032048851\&partnerID=40\&md5=560bdeecd60a2fe9ddb0c139457ce7e4}, author = {Martins, R.a b , Ma{\c c}arico, A.a b , Ferreira, I.a b , Nunes, R.a b , Bicho, A.a b , Fortunato, E.a b} } @article {Parthiban2010406, title = {Investigations on high visible to near infrared transparent and high mobility Mo doped In2O3 thin films prepared by spray pyrolysis technique}, journal = {Solar Energy Materials and Solar Cells}, volume = {94}, number = {3}, year = {2010}, note = {

cited By 35

}, pages = {406-412}, abstract = {

High visible to near infrared (NIR) transparent Mo (0-1 at\%) doped In2O3 (IMO) thin films with high carrier mobility were deposited on Corning-1737 glass substrates at 400 {\textdegree}C by spray pyrolysis experimental technique. The films were annealed in vacuum (\~{}1{\texttimes}10-4 mbar) at 550 {\textdegree}C for 45 min. XRD analysis confirmed that indium oxide belongs to cubic bixbyite structure. The preferred growth orientation along (2 2 2) plane for low Mo doping level shifts to (4 0 0) for higher Mo doping levels. Crystallite sizes extracted from the XRD data corroborate the changes in full-width at half-maximum due to the variation in Mo doping. Scanning electron microscopy study illustrates the evolution in surface microstructures as a function of Mo doping. The negative sign of Hall coefficient confirmed n-type conductivity. Films with high mobility of \~{}149 cm2/(V s), carrier concentration of \~{}1.0{\texttimes}1020 cm-3, resistivity of \~{}4.0{\texttimes}10-4 Ω cm and high figure of merit of \~{}1.02{\texttimes}10-2 Ω-1 were observed for post-annealed films (0.5 at\% Mo). The obtained high average transparency of \~{}83\% in the wavelength range 400-2500 nm confirms that transmittance is well extended into the NIR region. {\textcopyright} 2009 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.solmat.2009.10.017}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-75149167355\&partnerID=40\&md5=d9b4a2a7b5c28cbbdd92c9df6fc4a80e}, author = {Parthiban, S.a , Elangovan, E.b , Ramamurthi, K.a , Martins, R.b , Fortunato, E.b} } @article {{\'A}guas20034935, title = {Large Area Deposition of Polymorphous Silicon by Plasma Enhanced Chemical Vapor Deposition at 27.12 MHz and 13.56 MHz}, journal = {Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers}, volume = {42}, number = {8}, year = {2003}, note = {

cited By 32

}, pages = {4935-4942}, abstract = {

This work presents for the first time a study on the deposition of polymorphous silicon at an excitation frequency of 27.12 MHz in a large-area plasma enhanced chemical vapor deposition (PECVD) reactor. Moreover, the films produced at 13.56 MHz were also investigated to compare their performance with that of the films produced at 27.12 MHz. The SiH4/H2 plasma was characterized by impedance probe measurements, aiming to identify the plasma conditions that lead to produce polymorphous films, under quasi-isothermal conditions. The films were characterized by spectroscopic ellipsometry, infrared absorption, Raman spectroscopy, and hydrogen exodiffusion experiments. These techniques enable a detailed structural characterization of the polymorphous films and a study of the differences between the films deposited at 27.12 MHz and 13.56 MHz. Conductivity measurements were also performed to determine the transport properties of the films. The results show that by using a 27.12 MHz frequency, the growth rate increased by 70\% and a more stable, relaxed and denser structure was obtained.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0142023804\&partnerID=40\&md5=7cb9ecf78881258709f1eeeb71d1b8a1}, author = {{\'A}guas, H.a , Silva, V.a , Fortunato, E.a , Lebib, S.b , Roca i Cabarrocas, P.b , Ferreira, I.a , Guimar{\~a}es, L.a , Martins, R.a} } @article {Fernandes2004360, title = {Large area image sensing structures based on a-SiC:H: A dynamic characterization}, journal = {Sensors and Actuators, A: Physical}, volume = {113}, number = {3}, year = {2004}, note = {

cited By 17

}, pages = {360-364}, abstract = {

In recent works large area hydrogenated amorphous silicon p-i-n structures with low conductivity doped layers were proposed as single element image sensors. The working principle of this type of sensor is based on the modulation, by the local illumination conditions, of the photocurrent generated by a light beam scanning the active area of the device. In order to evaluate the sensor capabilities is necessary to perform a response time characterization. This work focuses on the transient response of such sensor and on the influence of the carbon contents of the doped layers. In order to evaluate the response time a set of devices with different percentage of carbon incorporation in the doped layers is analyzed by measuring the scanner-induced photocurrent under different bias conditions. {\textcopyright} 2004 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.sna.2004.03.007}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-3242733019\&partnerID=40\&md5=ac05b89776ca74ef5bfc2205e396f116}, author = {Fernandes, M.a , Vieira, M.a , Rodrigues, I.a , Martins, R.b} } @article {Fortunato1995135, title = {Large-area 1D thin-film position-sensitive detector with high detection resolution}, journal = {Sensors and Actuators: A. Physical}, volume = {51}, number = {2-3}, year = {1995}, note = {

cited By 32

}, pages = {135-142}, abstract = {

The aim of this work is to present the main optoelectronic characteristics of large-area one-dimensional position-sensitive detectors (1D TFPSDs) based on amorphous silicon (a-Si) p-i-n diodes. From that, the device resolution, response time and detectivity (defined as being the reciprocal of the noise equivalent power pattern) are derived and discussed concerning the field of applications of the 1D TFPSDs. {\textcopyright} 1996.

}, doi = {10.1016/0924-4247(95)01214-1}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000372450\&partnerID=40\&md5=7215caef9528e0eb71383845027da681}, author = {Fortunato, E.a , Lavareda, G.a , Martins, R.a , Soares, F.b , Fernandes, L.b} } @article {Ferreira200147, title = {Large-area polycrystalline p-type silicon films produced by the hot wire technique}, journal = {Solid State Phenomena}, volume = {80-81}, year = {2001}, note = {

cited By 1

}, pages = {47-52}, abstract = {

The role of the deposition pressure and hydrogen dilution in the production of p-type Si:H films by hot wire chemical vapor deposition, was investigated. The system used permits to obtain uniform and homogeneous films properties over a 10cm{\texttimes}10cm substrate area. As heated filament we used Ta, since Ta filaments have longer life period without deteriorating than the W filaments ones. In this work, we show that the electrical properties of the films produced are dependent on the process gas pressure. In the pressure range of 13.3 Pa (0.1 Torr) to 66.5 Pa (0.5Torr), the film{\textquoteright}s coplanar electrical conductivity at room temperature varies by more than two orders of magnitude, for films produced at same hydrogen dilution and filament temperature, reaching values of about 0.1 (Ωcm)-1, at deposition pressures of about 40-53Pa (0.3-0.4Torr). On the other hand, the increase in hydrogen dilution (from 87\% to 96\%) promotes the surface roughness due to an enlargement of grain sizes in the direction of the {220} diffraction planes as observed by SEM micrographs without changing the crystalline fraction (48-50\%) obtained by micro-Raman analysis.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034831461\&partnerID=40\&md5=2ca2e649eee271d0d435ae824136de27}, author = {Ferreira, I., Martins, R., Cabrita, A., Braz Fernandes, F., Fortunato, E.} } @article {Fernandes20061801, title = {The laser scanned photodiode: Theoretical and electrical models of the image sensor}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 4

}, pages = {1801-1804}, abstract = {

The laser scanned photodiode (LSP) presents a new concept of image sensor with application in fields where low cost, large area and design simplicity are of major importance. Over the past few years this type of sensor has been under investigation and development, where several structures have been tested and characterized. In this work we present the physical explanation of device operating principle, with recourse to numerical simulation applied to structures with different compositions of the doped layers. An electrical model for this type of device is presented, enabling a fast evaluation of the device characteristics by means of an electrical simulation program. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2006.01.077}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33745477385\&partnerID=40\&md5=91cdf6db6a139602aea7fc52cb55a818}, author = {Fernandes, M.a , Vieira, M.a , Martins, R.b} } @article {Martins1996137, title = {Lateral effects in amorphous silicon photodiodes}, journal = {Optical Materials}, volume = {5}, number = {1-2}, year = {1996}, note = {

cited By 2

}, pages = {137-144}, abstract = {

The objective of this work is to provide a basis for the interpretation of the a-Si:H photodiode behaviour under low illumination level conditions, where a lateral leakage current plays an important role on the devices{\textquoteright} performances when the doped collecting layer can not be considered a true equipotential. To determine this effect, a-Si:H p.i.n devices with small metal dot contacts, matrix distributed, were produced and analysed before and after etching the surrounding doped region of the metal collecting contact. The experimental data fit a model that includes the contribution of a lateral leakage current influencing the J-V characteristics, responsivity and the apparent light degradation behaviour of the device.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029753373\&partnerID=40\&md5=cac738af0101e28020bcbe0d29c001ef}, author = {Martins, R., Fortunato, E.} } @article {Martins19952927, title = {Lateral photoeffect in large area one-dimensional thin-film position-sensitive detectors based in a-Si:H P-I-N devices}, journal = {Review of Scientific Instruments}, volume = {66}, number = {4}, year = {1995}, note = {

cited By 34

}, pages = {2927-2934}, abstract = {

The aim of this work is to provide the basis for the interpretation, under steady state conditions, of the lateral photoeffect in p-i-n a-Si:H one-dimensional thin-film position-sensitive detectors (1D TFPSD) and the determination of its linear spatial detection limits, function of the device, and light spot source characteristics. This leads to the development of a model, based on the application of the Poisson, continuity, and current density equations in the p-i-n junction, where two thin resistive layers, as equipotentials, are considered on both sides of the doped layers. The experimental data recorded in 1D TFPSD devices with different performances are compared with the predicted curves and the obtained correlations discussed. {\textcopyright} 1995 American Institute of Physics.

}, doi = {10.1063/1.1145579}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029292137\&partnerID=40\&md5=35e0e7d037a69095d73aa411d1f79dd5}, author = {Martins, R., Fortunato, E.} } @article {Vieira19941147, title = {Light and temperature effect on pin a-Si: H device performance}, journal = {Vacuum}, volume = {45}, number = {10-11}, year = {1994}, note = {

cited By 0

}, pages = {1147-1149}, abstract = {

We report experimental data on light soaking of a-Si: H solar cells as well as the role played by the temperature on the metastable light-induced defect growth. We studied the temperature and intensity dependence on the photoconductivity, μτ product and density of states at the Fermi level (g(Ef)) and we found that the rate of defect growth on the i-layer depends on the quality of the material and on the annealing temperature, resulting from an equilibrium between light-induced and light-annealed defects. The photoresponse of the devices is mainly ruled by its microstructure, and depends on the fraction of hydrogen bounded on internal surfaces. Results suggest a correlation between the decrease of μτ product for electron and the increase of the fraction of hydrogen bonded on internal surfaces, suggesting structural changes during the degradation process. Data show, also, that the thermal annealing effect is worthless up to 70{\textdegree}C because of light-induced defect-generation being the dominant process in recombination mechanisms. {\textcopyright} 1994.

}, doi = {10.1016/0042-207X(94)90049-3}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028516798\&partnerID=40\&md5=f77e9a1c6a2dcb147c8c214c1b86c2d0}, author = {Vieira, M., Fortunato, E., Lavareda, G., Carvalho, C., Martins, R.} } @article {Martins19955317, title = {A linear array position sensitive detector based on amorphous silicon}, journal = {Review of Scientific Instruments}, volume = {66}, number = {11}, year = {1995}, note = {

cited By 2

}, pages = {5317-5321}, abstract = {

A linear array thin film position sensitive detector (LTFPSD) based on hydrogenated amorphous silicon (a-Si:H) is proposed for the first time. Taking advantage of the optical properties presented by a-Si:H devices, we have developed a LTFPSD with 128 integrated elements able to be used in 3D inspections/measurements. Each element consists of a one-dimensional LTFPSD, based on a p-i-n diode produced in a conventional PECVD system, where the doped layers are coated with thin resistive layers to establish the required device equipotentials. By proper incorporation of the LTFPSD into an optical inspection camera it will be possible to acquire information about an object/surface, through the optical cross-section method. The main advantages of this system, when compared with the conventional CCDs, are the low complexity of hardware and software used and that the information can be continuously processed (analog detection). {\textcopyright} 1995 American Institute of Physics.

}, doi = {10.1063/1.1146104}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029406930\&partnerID=40\&md5=6a62ee36aaeea06810bdca73981b9576}, author = {Martins, R.a , Lavareda, G.a , Fortunato, E.a , Soares, F.b , Fernandes, L.b , Ferreira, L.c} } @article {Fortunato19961212, title = {A linear array thin film position sensitive detector for 3D measurements}, journal = {Journal of Non-Crystalline Solids}, volume = {198-200}, number = {PART 2}, year = {1996}, note = {

cited By 3

}, pages = {1212-1216}, abstract = {

A novel compact linear thin film position sensitive detector with 128 elements, based on p-i-n a-Si:H devices was developed. The proper incorporation of this sensor into an optical inspection camera makes possible the acquisition of three dimension information of an object, using laser triangulation methods. The main advantages of this system, when compared with the conventional charge-coupled devices, are the low complexity of hardware and software used and that the information can be continuously processed (analogue detection).

}, doi = {10.1016/0022-3093(96)00114-7}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030563509\&partnerID=40\&md5=daf456bbcf335633c02918b6fe24ce8d}, author = {Fortunato, E., Soares, F., Lavareda, G., Martins, R.} } @article {{\'A}guas20051377, title = {Linearity and sensitivity of MIS position sensitive detectors}, journal = {Journal of Materials Science}, volume = {40}, number = {6}, year = {2005}, note = {

cited By 13

}, pages = {1377-1381}, abstract = {

The linearity and sensitivity of linear Position Sensitive Detectors (PSD) are the two principal characteristics of sensors to be optimised in sensor fabrication. This work presents several efforts made to understand the internal and external parameters that influence the linearity and sensitivity of Metal Insulator Semiconductor (MIS) linear PSD with an active length of 6 cm. The use of long sensitive areas allows the PSD to achieve greater resolution without the need of a highly accurate light spot integration mechanism. The PSD is built in a multi-layered structure consisting of Cr/a-Si:H (n+ doped)/a-Si:H (intrinsic)/SiOx (passivation layer)/Au, where the active a-Si:H layers were deposited by Modified Triode Plasma Enhanced Chemical Vapour Deposition (MTPECVD), which allows the deposition of good electronic grade material with a low (≈ 1 {\texttimes} 1015 cm-3) defect density inferred by CPM. The sensor linearity and sensitivity shows dependence on the sensor width to length ratio, SiOx layer and on the value of the load resistance. Sensitivities of more than 30 mV/cm were achieved with linearity near 99\%. Besides that, this type of MIS structure allows an improved spectral response in the near-UV region and has its maximum response at 540 nm. {\textcopyright} 2005 Springer Science + Business Media, Inc.

}, doi = {10.1007/s10853-005-0569-z}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-27544510778\&partnerID=40\&md5=11a023189673a83c45573406768f22f5}, author = {{\'A}guas, H., Pereira, L., Costa, D., Fortunato, E., Martins, R.} } @article {Pereira20082534, title = {Low temperature high k dielectric on poly-Si TFTs}, journal = {Journal of Non-Crystalline Solids}, volume = {354}, number = {19-25}, year = {2008}, note = {

cited By 8

}, pages = {2534-2537}, abstract = {

In this work, it is demonstrated the application of a high k dielectric, as hafnium oxide (HfO2), in poly-Si thin film transistors (TFTs) obtained by metal induced lateral crystallization (MILC). The dielectric layer was deposited at room temperature by sputtering, using argon and oxygen as process gases. As produced TFTs exhibit field effect mobility around 45 cm2 V-1 s-1and Ion/Ioff ratio of about 2 {\texttimes} 105. After annealing in a forming gas atmosphere for about 1 h at 200 {\textdegree}C, the threshold voltage and the sub-threshold slope are reduced, respectively from 4.8 to 2 V and from 1.6 to 1.4 V/dec. Nevertheless, by doing so, we notice a reduction on the field effect mobility of about 45\% and a decrease of about 2.5 times on the Ion/Ioff ratio. Longer annealing time will not improve the TFT{\textquoteright}s performance. {\textcopyright} 2008 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2007.09.036}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-43049138408\&partnerID=40\&md5=6b789d28d887043d05a52f9ae163bcea}, author = {Pereira, L., Barquinha, P., Fortunato, E., Martins, R.} } @article {Pereira20061125, title = {Low temperature processed hafnium oxide: Structural and electrical properties}, journal = {Materials Science in Semiconductor Processing}, volume = {9}, number = {6}, year = {2006}, note = {

cited By 23

}, pages = {1125-1132}, abstract = {

In this work hafnium oxide (HfO2) was deposited by r.f. magnetron sputtering at room temperature and then annealed at 200 {\textdegree}C in forming gas (N2+H2) and oxygen atmospheres, respectively for 2, 5 and 10 h. After 2 h annealing in forming gas an improvement in the interface properties occurs with the associated flat band voltage changing from -2.23 to -1.28 V. This means a reduction in the oxide charge density from 1.33{\texttimes}1012 to 7.62{\texttimes}1011 cm-2. After 5 h annealing only the dielectric constant improves due to densification of the film. Finally, after 10 h annealing we notice a degradation of the electrical film{\textquoteright}s properties, with the flat band voltage and fixed charge density being -2.96 V and 1.64{\texttimes}1012 cm-2, respectively. Besides that, the leakage current also increases due to crystallization. On the other hand, by depositing the films at 200 {\textdegree}C or annealing it in an oxidizing atmosphere no improvements are observed when comparing these data to the ones obtained by annealing the films in forming gas. Here the flat band voltage is more negative and the hysteresis on the C-V plot is larger than the one recorded on films annealed in forming gas, meaning a degradation of the interfacial properties. {\textcopyright} 2006 Elsevier Ltd. All rights reserved.

}, doi = {10.1016/j.mssp.2006.10.031}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33846115181\&partnerID=40\&md5=86e1bb5460adf1b7e907ecba0ebc07d7}, author = {Pereira, L., Barquinha, P., Fortunato, E., Martins, R.} } @article {Lorenz2010, title = {Low-temperature processed Schottky-gated field-effect transistors based on amorphous gallium-indium-zinc-oxide thin films}, journal = {Applied Physics Letters}, volume = {97}, number = {24}, year = {2010}, note = {

cited By 21

}, abstract = {

We have investigated the electrical properties of metal-semiconductor field-effect transistors (MESFET) based on amorphous oxide semiconductor channels. All functional parts of the devices were sputter-deposited at room temperature. The influence on the electrical properties of a 150 {\textdegree}C annealing step of the gallium-indium-zinc-oxide channel is investigated. The MESFET technology offers a simple route for processing of the transistors with excellent electrical properties such as low subthreshold swing of 112 mV/decade, gate sweep voltages of 2.5 V, and channel mobilities up to 15 cm2 /V s. {\textcopyright} 2010 American Institute of Physics.

}, doi = {10.1063/1.3525932}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-78650352232\&partnerID=40\&md5=e13e70609dd1668ba97dd55d037eea0e}, author = {Lorenz, M.a , Lajn, A.a , Frenzel, H.a , V. Wenckstern, H.a , Grundmann, M.a , Barquinha, P.b , Martins, R.b , Fortunato, E.b} } @article {Barquinha2010762, title = {Low-temperature sputtered mixtures of high-κ and high bandgap dielectrics for GIZO TFTs}, journal = {Journal of the Society for Information Display}, volume = {18}, number = {10}, year = {2010}, note = {

cited By 28

}, pages = {762-772}, abstract = {

This paper discusses the properties of sputtered multicomponent amorphous dielectrics based on mixtures of high-κ and high-bandgap materials and their integration in oxide TFTs, with processing temperatures not exceeding 1 50{\textdegree} C. Even if Ta2O5 films are already amorphous, multicomponent materials such as Ta2O5-SiO2 and Ta2O5-Al2O3 allow an increase in the bandgap and the smoothness of the films, reducing their leakage current and improving (in the case of Ta2O5-SiO2)the dielectric/semiconductor interface properties when these dielectrics are integrated in TFTs. For HfO2- based dielectrics, the advantages of multicomponent materials are even clearer: while HfO2 films present a polycrystalline structure and a rough surface, HfO2-SiO2 films exhibit an amorphous structure and a very smooth surface. The integration of the multicomponent dielectrics in GIZO TFTs allows remarkable performance, comparable with that of GIZO TFTs using SiO2 deposited at 400{\textdegree}C by PECVD. For instance, with Ta2O5-SiO2 as the dielectric layer, field-effect mobility of 35 cm2/(V-sec), close to 0 V turn-on voltage, an on/off ratio higher than 106, a subthreshold slope of 0.24 V/dec, and a small/recoverable threshold voltage shifts under constant current (ID = 10 μ,A) stress during 24 hours are achieved. Initial results with multilayers of SiO2/HfO 2-SiO2/SiO2 are also shown, allowing a lower leakage current with lower thickness and excellent device performance. {\textcopyright} Copyright 2010 Society for Information Display.

}, doi = {10.1889/JSID18.10.762}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77958198978\&partnerID=40\&md5=9fc1ee27aea4bdc27fe7807d925301d5}, author = {Barquinha, P.a , Pereira, L.a , Gon{\c c}alves, G.a , Kuscer, D.b , Kosec, M.b , Vil{\`a}, A.c , Olziersky, A.c , Morante, J.R.d e , Mart} } @article {Liu2015, title = {Low-Temperature, Nontoxic Water-Induced Metal-Oxide Thin Films and Their Application in Thin-Film Transistors}, journal = {Advanced Functional Materials}, year = {2015}, note = {

cited By 4; Article in Press

}, abstract = {

Here, a simple, nontoxic, and inexpensive "water-inducement" technique for the fabrication of oxide thin films at low annealing temperatures is reported. For water-induced (WI) precursor solution, the solvent is composed of water without additional organic additives and catalysts. The thermogravimetric analysis indicates that the annealing temperature can be lowered by prolonging the annealing time. A systematic study is carried out to reveal the annealing condition dependence on the performance of the thin-film transistors (TFTs). The WI indium-zinc oxide (IZO) TFT integrated on SiO2 dielectric, annealed at 300 {\textdegree}C for 2 h, exhibits a saturation mobility of 3.35 cm2 V-1 s-1 and an on-to-off current ratio of ≈108. Interestingly, through prolonging the annealing time to 4 h, the electrical parameters of IZO TFTs annealed at 230 {\textdegree}C are comparable with the TFTs annealed at 300 {\textdegree}C. Finally, fully WI IZO TFT based on YOx dielectric is integrated and investigated. This TFT device can be regarded as "green electronics" in a true sense, because no organic-related additives are used during the whole device fabrication process. The as-fabricated IZO/YOx TFT exhibits excellent electron transport characteristics with low operating voltage (≈1.5 V), small subthreshold swing voltage of 65 mV dec-1 and the mobility in excess of 25 cm2 V-1 s-1. {\textcopyright} 2015 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/adfm.201500056}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84926433781\&partnerID=40\&md5=8e7f711ea425ac91758ed11ead3b66e5}, author = {Liu, G.a , Liu, A.a , Zhu, H.a , Shin, B.b , Fortunato, E.c , Martins, R.c , Wang, Y.a , Shan, F.a} } @article {Shan2015541, title = {Low-voltage high-stability InZnO thin-film transistor using ultra-thin solution-processed ZrOx dielectric}, journal = {IEEE/OSA Journal of Display Technology}, volume = {11}, number = {6}, year = {2015}, note = {

cited By 2

}, pages = {541-546}, abstract = {

This paper deals with the evaluation of the performances of InZnO thin-film transistor (TFT) using as dielectric an ultra-thin solution-processed ZrOx layer. The ZrOx thin film was formed using ultraviolet (UV) photo-annealing method and shows a low leakage-current density of 4 nA/cm2 at 3.8 MV/cm and a large areal-capacitance of 775 nF/cm2 at 50 Hz. The InZnO TFT incorporating the UV-treated ZrOx dielectric exhibits high stable and enhanced characteristics, an on/off current ratio of 10

}, doi = {10.1109/JDT.2014.2366933}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84929333677\&partnerID=40\&md5=1ee3f9138763b84ffff07d5bde049f48}, author = {Shan, F.a , Liu, A.a , Liu, G.a , Meng, Y.a , Fortunato, E.b c , Martins, R.b c} } @article {Ferreira200160, title = {Mass spectroscopy analysis during the deposition of a-SiC:H and a-C:H films produced by hot wire and hot wire plasma-assisted techniques}, journal = {Applied Surface Science}, volume = {184}, number = {1-4}, year = {2001}, note = {

cited By 6

}, pages = {60-65}, abstract = {

This work analyse mainly the dissociation mechanism of the gas during the hot wire (HW) and hot wire plasma-assisted (HWPA) processes used to produce hydrogenated carbon films and silicon-carbide, using ethylene and silane as gas sources. The results show that ethylene is better decomposed by plasma-enhanced chemical vapour deposition (PECVD) than HW process. The data also show that the HWPA leads to a better carbon {\textcopyright} incorporation than HW processes, when silicon carbide alloys are produced and, that the presence of atomic hydrogen (H) is beneficial for all processes. That is, the presence of the plasma and H lead to the formation of higher C radicals such as methylsilane (CH3SiH3), ethylsilane (C2H5SiH3) and silorane (C2H4SiH2), whose contributions are enhanced as the fraction of ethylene (Feth) in the gas mixture increases. {\textcopyright} 2001 Published by Elsevier Science B.V.

}, doi = {10.1016/S0169-4332(01)00478-0}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035852208\&partnerID=40\&md5=5319cdeb173c3fef0cd7b9f65817e167}, author = {Ferreira, I., Silva, V., �?guas, H., Fortunato, E., Martins, R.} } @article {Fortunato1993797, title = {Material properties, project design rules and performances of single and dual-axis a-Si:H large area position sensitive detectors}, journal = {Journal of Non-Crystalline Solids}, volume = {164-166}, number = {PART 2}, year = {1993}, note = {

cited By 27

}, pages = {797-800}, abstract = {

We have developed large area (up to 80mm{\texttimes}80mm) Thin Film Position Sensitive Detectors (TFPSD) based on hydrogenated amorphous silicon (a-Si:H). Although crystalline silicon PSDs have been realized and applied to optical systems, their detection area is small (less than 10mm{\texttimes}10mm), which implies the need of optical magnification systems for supporting their field of applications towards large area inspection systems, which does not happen by using a-Si:H devices. The key factors for the TFPSDs resolution are the thickness uniformity of the constituting layers, the geometry and the position of the contacts. In this paper we present data on single and dual-axis rectangular TFPSDs correlating, their performances with the different underlying lateral effects. For the single axis-detector, with two opposite extended contacts, the output photocurrent difference to sum ratio is a linear function of the position of a narrow incident light beam, even for low illumination levels (below 20 lux). For the dual-axis detector with extended contacts, at all four sides (except for small gaps at the vertices due to edge effects) an almost linear relation has been found between the incident light spot position along both axis and the corresponding output photocurrents. {\textcopyright} 1993.

}, doi = {10.1016/0022-3093(93)91117-L}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027906762\&partnerID=40\&md5=73f3eddfabed52cbbfa2d77c368851cd}, author = {Fortunato, E.a , Vieira, M.a , Lavareda, G.a , Ferreira, L.b , Martins, R.a} } @article {Martins2004, title = {Materials Science Forum: Preface}, journal = {Materials Science Forum}, volume = {455-456}, year = {2004}, note = {

cited By 0

}, pages = {ix-x}, abstract = {n/a}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17144436042\&partnerID=40\&md5=1b0c63a4245b24b31bcb3dd699c25ca3}, author = {Martins, R., Fortunato, E., Ferreira, I., Dias, C.J.} } @article {Martins2001, title = {Materials Science Forum: Preface}, journal = {Materials Science Forum}, volume = {382}, year = {2001}, note = {

cited By 0

}, pages = {V}, abstract = {n/a}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035672405\&partnerID=40\&md5=b43961f06d3126c6a82663d577275c97}, author = {Martins, R.} } @article {Pereira20082319, title = {Metal contamination detection in nickel induced crystallized silicon by spectroscopic ellipsometry}, journal = {Journal of Non-Crystalline Solids}, volume = {354}, number = {19-25}, year = {2008}, note = {

cited By 1

}, pages = {2319-2323}, abstract = {

In this paper a new approach is presented for the simulation of spectroscopic ellipsometry (SE) data to estimate the level of nickel (Ni) contamination in silicon crystallized by metal induced crystallization (MIC). The method employs the addition of Ni as reference for a Bruggemann effective medium approximation (BEMA) to simulate the optical response of the crystallized silicon. This new approach is sensitive to changes in the initial average metal thickness used on the crystallization process to thickness values as low as 0.05 nm. This corresponds to a volume fraction of 0.24\%, confirmed by Rutherford backscattering spectrometry (RBS) where it was observed that the Ni volume fraction detected by SE varies linearly with the metal amount inside the crystallized films determined by RBS. {\textcopyright} 2008.

}, doi = {10.1016/j.jnoncrysol.2007.09.027}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-43049138411\&partnerID=40\&md5=105a284038f5d55b87da33c2e4ca0c47}, author = {Pereira, L.a , {\'A}guas, H.a , Beckers, M.b , Martins, R.M.S.b , Fortunato, E.a , Martins, R.a} } @article {Pereira20051387, title = {Metal induced crystallization: Gold versus aluminium}, journal = {Journal of Materials Science}, volume = {40}, number = {6}, year = {2005}, note = {

cited By 9

}, pages = {1387-1391}, abstract = {

In this work metal induced crystallization was studied using aluminium and gold deposited over 150 nm amorphous silicon films grown by LPCVD. Aluminium and gold layers with thickness between 1 and 5 nm were deposited on the silicon films and after that, the samples were annealed at 500{\textdegree}C from 5 up to 30 h. When the crystallization is induced through a gold layer, the Si crystalline fraction is higher than when using aluminium. For samples crystallized for 30 h at 500{\textdegree}C with 2 nm of metal a crystalline fraction of 57.5\% was achieved using gold and only 38.7\% when using aluminium. {\textcopyright} 2005 Springer Science + Business Media, Inc.

}, doi = {10.1007/s10853-005-0571-5}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-27544509099\&partnerID=40\&md5=7e0c81288beda8d7e4bd45c42589d108}, author = {Pereira, L.a , {\'A}guas, H.a , Vilarinho, P.b , Fortunato, E.a , Martins, R.a} } @article {Kholkin20021311, title = {Metal-ferroelectric thin film devices}, journal = {Journal of Non-Crystalline Solids}, volume = {299-302}, number = {PART 2}, year = {2002}, note = {

cited By 4

}, pages = {1311-1315}, abstract = {

Ferroelectric and high dielectric permittivity films are currently being investigated in view of their use as gate dielectrics in MIS structures. Along with the suppression of tunnelling currents at small gate thickness, they provide a memory function to MIS structures, which can be used in non-volatile memory applications. In this work we report fabrication and characterization of novel metal-ferroelectric-amorphous silicon structures. The structures consist of glass/ITO substrates coated with PZT 20/80 films (sol-gel) followed by an active layer (i-a-SiC:H, deposited by plasma enhanced chemical vapor deposition (PECVD)). A strong capacitance hysteresis is observed in C-V curves in electron accumulation region (VG \> 0), accompanied with a large increase in the capacitance of ferroelectric-semiconductor structures at low frequencies. Threshold voltage for electron accumulation is about 10 V being dependent on the ferroelectric polarization switching. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0022-3093(01)01152-8}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-6444245868\&partnerID=40\&md5=c68928372b13658c546acf4e70c8f341}, author = {Kholkin, A.L.b , Martins, R.a , {\'A}guas, H.a , Ferreira, I.a , Silva, V.a , Smirnova, O.A.b , Costa, M.E.V.b , Vilarinho, P.M.b ,} } @article {Contreras20108173, title = {Micro cantilever movement detection with an amorphous silicon array of position sensitive detectors}, journal = {Sensors}, volume = {10}, number = {9}, year = {2010}, note = {

cited By 6

}, pages = {8173-8184}, abstract = {

The movement of a micro cantilever was detected via a self constructed portable data acquisition prototype system which integrates a linear array of 32 1D amorphous silicon position sensitive detectors (PSD). The system was mounted on a microscope using a metal structure platform and the movement of the 30 μm wide by 400 μm long cantilever was tracked by analyzing the signals acquired by the 32 sensor array electronic readout system and the relevant data algorithm. The obtained results show a linear behavior of the photocurrent relating X and Y movement, with a non-linearity of about 3\%, a spatial resolution of less than 2μm along the lateral dimension of the sensor as well as of less than 3μm along the perpendicular dimension of the sensor, when detecting just the micro-cantilever, and a spatial resolution of less than 1μm when detecting the holding structure. {\textcopyright} 2010 by the authors.

}, doi = {10.3390/s100908173}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77957990644\&partnerID=40\&md5=32ad9dd7706b7f65924259364c7017e2}, author = {Contreras, J.C.a , Costa, D.a , Pereira, S.a , Fortunato, E.a , Martins, R.a , Wierzbicki, R.b , Heerlein, H.b , Ferreira, I.a} } @article {Malik19981092, title = {Microcrystalline thin metal oxide films for optoelectronic applications}, journal = {Journal of Non-Crystalline Solids}, volume = {227-230}, number = {PART 2}, year = {1998}, note = {

cited By 15

}, pages = {1092-1095}, abstract = {

We report the properties and optoelectronic applications of transparent and conductive indium and tin oxide films prepared by the spray pyrolysis method and doped with Sn or F, respectively. The film properties have been measured using X-ray diffraction, optical and electrical absorption. As examples of applications we produced a set of selective optical detectors for different spectral regions, covering the wavelength range from 0.25 to 1.1 μm, based on metal oxide-semiconductor heterostructures and using different substrates such as: GaP, GaSe, AlxGa1-xAs, GaAs and Si. The fabricated devices exhibit several features such as: production simplicity, high quantum efficiency, uniform sensitivity over the entire active area and a high response speed. Finally, we present a high quantum efficiency and solar blind monocrystalline zinc sulphide optical sensor fabricated by spray deposition as an alternative to the ultraviolet-enhanced SiC and GaN photodetectors and the performances of a solar cell. {\textcopyright} 1998 Elsevier Science B.V. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032068563\&partnerID=40\&md5=b7eab148cc919839491fd23b1e2f137e}, author = {Malik, A.a , S{\^e}co, A.c , Fortunato, E.b , Martins, R.b} } @article {Alendouro2004827, title = {Microstructural characterization and properties of a glass and a glassceramic made from municipal incinerator bottom ash}, journal = {Materials Science Forum}, volume = {455-456}, year = {2004}, note = {

cited By 1

}, pages = {827-830}, abstract = {

A glass was made using bottom ash produced by a Portuguese municipal solid waste (MSW) incinerator. The bottom ash was the single batch material used in the formation of the glass, which was obtained through a conventional melt-quenching method. The glass was then converted to glass-ceramic for further recycling to construction materials. After submitting the glass samples to several heat treatments, between 820 and 1050{\textdegree}C and during different times, it was verified that the optimum heat treatment schedule for the ceramization of the glass was at 1000{\textdegree}C for 10h, as confirmed by microstructural observation and by X-ray diffraction. The major crystalline phases precipitated in the glass-ceramic were wollastonite (CaSiO3) and diopside (Ca(Mg,Al)(Si,Al)2O6). Microstructural analysis of the glass-ceramic revealed that the crystalline phases were present as dendrites and fiber-like structures that were homogeneously distributed in the material. The glassceramic showed good mechanical properties with a hardness of 5.6 MPa and a bending strength of 101 MPa. This material had a density of 2.8 gcm-3 and a thermal expansion coefficient of 9.10-6{\textdegree}C-1. The glass and the glass-ceramic showed an excellent chemical stability against leaching in acidic solution and in alkaline solution. In summary, both the glass and the glass-ceramic have good chemical and mechanical properties and can, therefore, be applied as construction materials.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-3142698407\&partnerID=40\&md5=0236c72a25f8a81a16f0350028d794c9}, author = {Alendouro, M.S.J.G.a , Monteiro, R.C.C.a , Figueiredo, C.F.M.L.a , Martins, R.M.S.a , Silva, R.J.C.a , Ferro, M.C.b , Fernandas,} } @article {Wojcik201213268, title = {Microstructure control of dual-phase inkjet-printed a-WO 3/TiO 2/WO X films for high-performance electrochromic applications}, journal = {Journal of Materials Chemistry}, volume = {22}, number = {26}, year = {2012}, note = {

cited By 28

}, pages = {13268-13278}, abstract = {

The microstructural aspects related to crystalline or amorphous structure of as-deposited and annealed films of sol-gel-derived WO 3 are shown in the literature to be critical for electrochromic (EC) performance. In consideration of ion insertion materials, there is a need for developing light and at the same time nanocrystalline structures to improve both coloration efficiency and switching kinetics. By controlling microstructure and morphology, one could design a material with optimal EC performance. This report compares the microstructural and morphological characteristics of standard WO 3 wet deposition techniques versus inkjet printing technology (IPT), correlating these features with their optical and electrochemical performances, emphasizing the importance of the dual-phase a-WO 3/TiO 2/WO X film composition proposed in this work for high-performance EC applications. The effect of the type and content of metal oxide nanoparticles in the precursor sols formulated in various peroxopolytungstic acid (PTA) and oxalic acid (OAD) proportions on film properties is comprehensively studied using multi-factorial design of experiment (DOE). To the authors{\textquoteright} knowledge, no other report on sol-gel deposition of inorganic EC materials via the inkjet printing technique exists, in which furthermore the film crystallinity can be controlled under low-temperature process conditions. The proposed method enables development of EC films which irrespective of their composition (a-WO 3, a-WO 3/TiO 2 or a-WO 3/TiO 2/WO X) outperform their amorphous or nanocrystalline analogues presented as the state-of-the-art due to their superior chemical and physical properties. {\textcopyright} 2012 The Royal Society of Chemistry.

}, doi = {10.1039/c2jm31217d}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84862529721\&partnerID=40\&md5=be9a14315ad8a438f35049a6a90db248}, author = {Wojcik, P.J., Cruz, A.S., Santos, L., Pereira, L., Martins, R., Fortunato, E.} } @article {Pimentel2016, title = {Microwave synthesized ZnO nanorod arrays for UV sensors: A seed layer annealing temperature study}, journal = {Materials}, volume = {9}, number = {4}, year = {2016}, note = {

cited By 0

}, abstract = {

The present work reports the influence of zinc oxide (ZnO) seed layer annealing temperature on structural, optical and electrical properties of ZnO nanorod arrays, synthesized by hydrothermal method assisted by microwave radiation, to be used as UV sensors. The ZnO seed layer was produced using the spin-coating method and several annealing temperatures, ranging from 100 to 500 {\textdegree}C, have been tested. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and spectrophotometry measurements have been used to investigate the structure, morphology, and optical properties variations of the produced ZnO nanorod arrays regarding the seed layer annealing temperatures employed. After the growth of ZnO nanorod arrays, the whole structure was tested as UV sensors, showing an increase in the sensitivity with the increase of seed layer annealing temperature. The UV sensor response of ZnO nanorod arrays produced with the seed layer annealed temperature of 500 {\textdegree}C was 50 times superior to the ones produced with a seed layer annealed at 100 {\textdegree}C. {\textcopyright} 2016 by the authors.

}, doi = {10.3390/ma9040299}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84965049893\&partnerID=40\&md5=31aea42478cbcd11fd58cc5009876308}, author = {Pimentel, A., Ferreira, S.H., Nunes, D., Calmeiro, T., Martins, R., Fortunato, E.} } @article {{\'A}guas200473, title = {MIS photodiodes of polymorphous silicon deposited at higher growth rates by 27.12 MHz PECVD discharge}, journal = {Materials Science Forum}, volume = {455-456}, year = {2004}, note = {

cited By 0

}, pages = {73-76}, abstract = {

This work presents a comparative study between MIS photodiodes produced using high quality amorphous silicon (a-Si:H), deposited by PECVD at 2{\r A}/s, using 13.56 MHz frequency and polymorphous silicon (pm-Si) deposited at 3{\r A}/s using a 27.12 MHz frequency. The results show that the pm-Si:H outperforms the a-Si:H MIS photodiodes by having a rectification ratio of 107, and photosensitivity at AM1.5 conditions of 107, under 1V reverse bias. Apart from that, the pm-Si:H photodiode presents a higher open circuit voltage and better fill factor than a-Si:H MIS photodiode. These results prove that quality devices can be produced at high growth rates by using pm-Si:H. In this work the photodiode performances were correlated to the films properties, aiming to determine the characteristics responsible for the performances exhibited by the pm-Si:H devices.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-3142771246\&partnerID=40\&md5=4a2931475823d3ec7131073b102783e3}, author = {{\'A}guas, H., Pereira, L., Raniero, L., Fortunato, E., Martins, R.} } @article {Fantoni1997110, title = {Modelling a μc-Si:H p-i-n device under non-uniform illumination}, journal = {Thin Solid Films}, volume = {296}, number = {1-2}, year = {1997}, note = {

cited By 0

}, pages = {110-113}, abstract = {

Microcrystalline p-i-n silicon devices are a prospective contender for application in large-area optoelectronics. In this paper we analyse the behaviour of a μc-Si:H p-i-n photodevice under non-uniform illumination. The effect of a spatially non-uniform illumination is to create lateral electric fields and current flows inside the structure. We present in this paper a numerical application of a complete bidimensional model describing the transport properties within the structure. The continuity equations forholes and electrons together with Poisson{\textquoteright}s equation are solved simultaneously along the two directions parallel and perpendicular to the junction. The results of simulating p-i-n μc-Si:H junctions under non-uniform illumination show that the generated lateral effects depend not only in intensity but also in direction on the wavelength of the incident radiation. {\textcopyright} 1997 Elsevier Science S.A.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031099285\&partnerID=40\&md5=554b55d2c6a9166a1cb8b2afecb14ba5}, author = {Fantoni, A., Vieira, M., Cruz, J., Martins, R.} } @article {Chandra20124556, title = {Modulations in effective work function of platinum gate electrode in metal-oxide-semiconductor devices}, journal = {Thin Solid Films}, volume = {520}, number = {14}, year = {2012}, note = {

cited By 4

}, pages = {4556-4558}, abstract = {

Reduction in the accumulation capacitance value was more in Si metal-oxide-semiconductor devices than that of Ge metal-oxide-semiconductor devices after a thermal treatment irrespective of the annealing environment. Relatively, thermal treatment in oxygen environment improves the interface quality of HfO2/Ge stacks considerably, when compared with HfO 2/Si stacks. Whereas, the forming gas annealing at a temperature of 400 {\textdegree}C was not so effective in improving the interface quality at HfO 2/Si stack. The presence of induced negatively charged hydrogen atom in Ge lessens the Fermi level pinning at HfO2 and Ge interface. {\textcopyright} 2011 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2011.10.137}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84860300789\&partnerID=40\&md5=0298b5fbcdc8009d3c032919bbb87668}, author = {Chandra, S.V.J.a , Fortunato, E.a , Martins, R.a , Choi, C.-J.b c} } @article {Alexa20151288, title = {Morphological and optical characterization of transparent thin films obtained at low temperature using ZnO nanoparticles}, journal = {Journal of Optoelectronics and Advanced Materials}, volume = {17}, number = {9-10}, year = {2015}, note = {

cited By 0

}, pages = {1288-1295}, abstract = {

Transparent metal oxides thin films are a class of inorganic conductors and semiconductors with significant importance for use in portable electronics, displays, flexible electronics, multi-functional windows and solar cells. Due to the recent development of transparent and flexible electronics, there is a growing interest in depositing metal-oxide thin-film on plastic substrates that can offer flexibility, lighter weight, and potentially lead to cheaper manufacturing by allowing printing and rollto- roll processing. The plastic substrates, however, limit device processing to below 200oC. In this context, the deposition of high-performance semiconductor thin films from dispersions of pre-prepared oxide nanoparticles at temperatures below 200oC represents a potential key route. This paper reports on the preparation of ZnO transparent thin films using solutionprocessed nanoparticles (NPs) precipitated from zinc acetate alcoholic solution with potassium hydroxide. The nanoparticles size distribution, microstructure and crystallinity were measured by dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The thin films were deposited by spin-coating onto soda lima glass substrate, using a dispersion of 1wt\% ZnO NPs. The morphology of the films annealed at 120 and 180oC, observed by atomic force microscopy and cross-section scanning electron microscopy, shows columnar grains with diameter ranging between 20 and 70 nm, depending on the conditions of depositions. Optical measurements indicated high transparency, between 85 and 94 \%, in the visible range, a direct nature of band-to-band transitions and band gap values between 3,22 and 3,32 eV. The refractive index and extinction coefficient have been calculated from optical transmittance and reflectance spectra.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84953394124\&partnerID=40\&md5=07e550fc66e59b6c48c557f4390be9c2}, author = {Alexa, A.a , Tigau, N.b , Alexandru, P.a , Pimentel, A.c , Branquinho, R.c , Salgueiro, D.c , Calmeiro, T.c , Martins, R.c , For} } @article {Ferreira2000248, title = {Morphological and structural characteristics presented by the Cu-Sn-Cu metallurgical system used in electronic joints}, journal = {Materials Science and Engineering A}, volume = {288}, number = {2}, year = {2000}, note = {

cited By 6

}, pages = {248-252}, abstract = {

Results are presented concerning the morphological and structural characteristics exhibited by the Cu-Sn-Cu system to be used in electronic lead-free soldering processes, under different process temperatures and pressures. The results show that the Cu3Sn or Cu6Sn5 phases needed to supply the thermal, mechanical and electrical stability to the joints formed require Sn layers (either electrodeposited or by using preforms) whose thickness depends on the process temperature used. For process temperatures of 533 K the thickness of the Sn layer should be above 20 μm, while for process temperatures of 573 K, the Sn thickness required is reduced to 10 μm. The joints formed support shear stresses above 12 MPa, as required by electronic standards. Apart from that, microcracks start appearing if an excess of Sn is used during the soldering operation. The set of tests performed indicates that this new joint is quite promising to substitute the conventional solder process applied to power diodes.

}, doi = {10.1016/S0921-5093(00)00859-5}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034273959\&partnerID=40\&md5=8415513262cc5280db362f3e974a40f9}, author = {Ferreira, J.a , Fernandes, B.a , Gon{\c c}alves, C.a , Nunes, P.a , Fortunato, E.a , Martins, R.a , Martins, J.I.b , Marv{\~a}o, A.P.c} } @article {Ferreira2002237, title = {Morphology and structure of nanocrystalline p-doped silicon films produced by hot wire technique}, journal = {Vacuum}, volume = {64}, number = {3-4}, year = {2002}, note = {

cited By 9

}, pages = {237-243}, abstract = {

In this paper we report results of nanocrystalline p-doped silicon films produced by hot wire chemical vapour deposition technique with Ta filaments, using a pre-mixed gas containing silane, diborane, methane, helium and hydrogen. The data obtained show that the films produced exhibit good optoelectronic properties and show a surface morphology dependent on the filament temperature and hydrogen dilution. The increase in the filament temperature, keeping constant the hydrogen dilution (87\%), promotes the preferential growth of the crystals in the {220} direction, giving rise to a pyramidal-like surface structure. This behaviour is observed by the SEM micrographs as well as by the micro-Raman and X-ray diffraction analyses. On the other hand, using a constant filament temperature, the increase in the hydrogen dilution contributes to an increase in both {111} and {220} diffraction peaks. Thus, by combining both filament temperature and hydrogen dilution the film surface can be controlled from a smooth to a pyramidal-like structure, without decreasing the crystalline fraction of the films. The structure and morphology is also reflected in the stability of the electrical dark conductivity. We observe that this property depends on the temperature range of the measurements and on the exposition time of films to the atmospheric conditions. {\textcopyright} 2002 Elsevier Science Ltd. All rights reserved.

}, doi = {10.1016/S0042-207X(01)00297-4}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036135403\&partnerID=40\&md5=d69563982202fadaecfce3a1af1490c7}, author = {Ferreira, I., Cabrita, A., Braz Fernandes, F., Fortunato, E., Martins, R.} } @article {Fortunato20063, title = {Multifunctional thin film zinc oxide semiconductors: Application to electronic devices}, journal = {Materials Science Forum}, volume = {514-516}, number = {PART 1}, year = {2006}, note = {

cited By 8

}, pages = {3-7}, abstract = {

In this paper we report some of the recent advances in transparent thin film oxide semiconductors, specifically zinc oxide (ZnO), produced by rf magnetron sputtering at room temperature with multifunctional properties. By controlling the deposition parameters it is possible to produce undoped material with electronic semiconductor properties or by doping it to get either n-type or p-type semiconductor behavior. In this work we refer our experience in producing n-type doping ZnO as transparent electrode to be used in optoelectronic applications such as solar cells and position sensitive detectors while the undoped ZnO can be used as UV photodetector or ozone gas sensor or even as active layer of fully transparent thin film transistors.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34347397216\&partnerID=40\&md5=0f5a042f1b874c316b4d98c238823d61}, author = {Fortunato, E., Gon{\c c}alves, A., Marques, A., Pimentel, A., Barquinha, P., {\'A}guas, H., Pereira, L., Raniero, L., Gon{\c c}alves, G., Ferr} } @article {Prabakaran20082632, title = {n-PS/a-Si:H heterojunction for device application}, journal = {Journal of Non-Crystalline Solids}, volume = {354}, number = {19-25}, year = {2008}, note = {

cited By 3

}, pages = {2632-2636}, abstract = {

In this work, we investigate the role of amorphous silicon (a-Si:H) thin films deposited by a plasma enhanced chemical vapor deposition (PECVD) technique on porous silicon (PS) to facilitate its water vapor and oxygen gas sensing properties using its electrical response. Overall we notice a rectifying behavior from a-Si:H/PS heterojunction device, where a current enhancement of one and four orders of magnitude was observed in the presence of oxygen gas and water vapor, in comparison with atmospheric air at room temperature, respectively. The photoluminescence (PL) investigation of PS shows a slight blue shift in the PL emission band from 1.72 to 1.77 eV and the intensity of the PL is enhanced by a factor of 5.4 with increase of porosity from 21\% to 77\%. This PL emission may originate from the O-Si-H related absorbance bands. Alternatively, quenching of the PL intensity was observed after a-Si:H films were deposited on PS specimens. Besides, micro-Raman and atomic force microscopic (AFM) analyse were carried out to understand the structure and morphological features of the PS and a-Si:H/PS specimens. {\textcopyright} 2007 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2007.09.115}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-43049148311\&partnerID=40\&md5=26dede00596c45745eb80f0893a0b9e2}, author = {Prabakaran, R., Aguas, H., Fortunato, E., Martins, R., Ferreira, I.} } @article {Barquinha2012435, title = {N-type oxide semiconductor thin-film transistors}, journal = {Springer Series in Materials Science}, volume = {156}, number = {1}, year = {2012}, note = {

cited By 0

}, pages = {435-476}, abstract = {

This chapter gives an overview about GIZO TFTs, comprising an introductory section about generic TFT structure and operation, different semiconductor technologies for TFTs - with special emphasis on AOSs and particularly on GIZO - and then some experimental results obtained for GIZO TFTs fabricated in CENIMAT. Thin-film transistors (TFTs) are important electronic devices which are predominantly used as On/Off switches in active matrix backplanes of flat panel displays (FPDs), namely liquid crystal displays (LCDs) and organic light emitting device (OLED) displays. Even if a-Si:H is still dominating the TFT market in terms of semiconductor technology, oxide semiconductors are emerging as one of the most promising alternatives for the next generation of TFTs, bringing the possibility of having fully transparent devices, low processing temperature, low cost, high performance and electrically stable properties [1, 2]. Amorphous oxide semiconductors (AOS) such as Gallium-Indium-Zinc oxide (GIZO) [3, 4], even if fabricated at temperatures below 150{\textdegree}, are currently capable of providing transistors with field-effect mobility (μFE) exceeding 20 cm2V-1 s-1, threshold voltage (VT) close to 0V, On/Off ratios above 108, subthreshold swing (S) around 0:20V dec-1 and fully recoverable VT shift (ΔVT) lower than 0.5V after 24 h stress with constant drain current of 10 μA. {\textcopyright} Springer-Verlag Berlin Heidelberg 2012.

}, doi = {10.1007/978-3-642-23521-4_15}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84870484114\&partnerID=40\&md5=586517a4247975fbbedcd1c149840c8e}, author = {Barquinha, P., Martins, R., Fortunato, E.} } @article {Ferreira2001137, title = {Nanocrystalline p-type silicon films produced by hot wire plasma assisted technique}, journal = {Materials Science and Engineering C}, volume = {15}, number = {1-2}, year = {2001}, note = {

cited By 3

}, pages = {137-140}, abstract = {

We report in this paper the influence of the rf power on the properties of p-type silicon thin films produced by hot wire plasma assisted chemical vapor deposition (HWPA-CVD) technique, using a gas mixture containing SiH4, B2H6, CH4 and H2. The influence of the rf power in the film morphology, its structure and its composition has been determined by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and infrared spectroscopy. The electrical dark conductivity, activation energy, optical band gap and growth rate values for the different rf power was also evaluated. The data achieved show that rf power rules the surface morphology, the film structure and its electrical characteristics. {\textcopyright} 2001 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0928-4931(01)00249-1}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034840712\&partnerID=40\&md5=9bf41ae9bb4ab3c6d4f89c60e3cbf5b0}, author = {Ferreira, I.a , Fernandes, F.Braza , Vilarinho, P.b , Fortunato, E.a , Martins, R.a} } @article {Ferreira1999147, title = {Nanocrystalline silicon carbon doped films prepared by hot wire technique}, journal = {Vacuum}, volume = {52}, number = {1-2}, year = {1999}, note = {

cited By 12

}, pages = {147-152}, abstract = {

In this work we present data concerning the structure, composition and electro-optical performances of nanocrystalline silicon carbide doped films produced at the different filament temperatures and hydrogen dilution ratios. The XRD spectra reveal the presence of the typical Si peaks ascribed to (111) (220) and (311) diffraction planes, where no traces of the carbon peaks were found. The average grain sizes ranges from 10 nm to 30 nm, depending on the temperature of filament and hydrogen dilution used. We observed an enhancement of the peak ascribed to the (220) plane when high H dilution rates are used, meaning that the film starts being textured. The infrared data reveal the typical silicon carbide modes and a hydrogen content that varies from 3\% to 1\%, with the increase of the filament temperature. Besides that, the IR spectra show the typical SiO2 and SiO modes, associated to the oxide species that are mainly incorporated in the surface of the films and can be removed by proper wet etching. The planar conductivity is enhanced as the temperature of the filament is increased, being the highest conductivity achieved in the range of 0.2 (Ωcm)-1 and almost non activated. {\textcopyright} 1998 Elsevier Science Ltd. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032762762\&partnerID=40\&md5=b4fa4b0fb5c2cc5a01332e6a28788210}, author = {Ferreira, I., Fernandas, B., Martins, R.} } @article {Lyubchyk201525, title = {Nanocrystalline thin film silicon solar cells: A deeper look into p/i interface formation}, journal = {Thin Solid Films}, volume = {591}, year = {2015}, note = {

cited By 1

}, pages = {25-31}, abstract = {

The p/i interface plays a major role in the conversion efficiency of nanocrystalline silicon (nc-Si:H) solar cells. Under plasma-enhanced chemical vapor deposition (PECVD) of the intrinsic (i) nc-Si:H layer, ion bombardment can severely affect the underlying p-doped layer and degrade the solar cell performance. The core of the present work is to investigate the effect of light and heavy ion bombardment on the structural modifications of the p-layer during the p/i interface formation. The properties of the nc-Si:H materials deposited under distinct conditions are analyzed and correlated to the deposition rate and the resulting cell efficiency. To recreate the ion bombardment during the initial stages of the i-layer deposition on the p-layer, hydrogen plasma treatment was performed for 30 s (light ion bombardment), after which a flux of silane was introduced into the deposition chamber in order to initiate the heavy ion bombardment and growth of an ultra-thin (5 nm) i-layer. The structural changes of the p-type nc-Si:H layers were observed by spectroscopic ellipsometry. The obtained results confirm that detrimental structural modifications (e.g. partial amorphization of the sub-surface region and bulk) occur in the p-layer, caused by the ion bombardment. To minimize this effect, a protective buffer layer is investigated able to improve the performance of the solar cells fabricated under increased growth rate conditions. {\textcopyright} 2015 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2015.08.016}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84942037268\&partnerID=40\&md5=d43075432bd9571cfcda387b3cd1a3df}, author = {Lyubchyk, A.a , Filonovich, S.A.a , Mateus, T.a , Mendes, M.J.a , Vicente, A.a , Leit{\~a}o, J.P.b , Falc{\~a}o, B.P.b , Fortunato, E.a} } @article {Pereira2006339, title = {Nanostructure characterization of high k materials by spectroscopic ellipsometry}, journal = {Applied Surface Science}, volume = {253}, number = {1 SPEC. ISS.}, year = {2006}, note = {

cited By 11

}, pages = {339-343}, abstract = {

In this work, the optical and structural properties of high k materials such as tantalum oxide and titanium oxide were studied by spectroscopic ellipsometry, where a Tauc-Lorentz dispersion model based in one (amorphous films) or two oscillators (microcrystalline films) was used. The samples were deposited at room temperature by radio frequency magnetron sputtering and then annealed at temperatures from 100 to 500 {\textdegree}C. Concerning the tantalum oxide films, the increase of the annealing temperature, up to 500 {\textdegree}C does not change the amorphous nature of the films, increasing, however, their density. The same does not happen with the titanium oxide films that are microcrystalline, even when deposited at room temperature. Data concerning the use of a four-layer model based on one and two Tauc-Lorentz dispersions is also discussed, emphasizing its use for the detection of an amorphous incubation layer, normally present on microcrystalline films grown by sputtering. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.apsusc.2006.06.007}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33750516728\&partnerID=40\&md5=5ade143ac64ae1a29088a2f13b8a70c5}, author = {Pereira, L., {\'A}guas, H., Fortunato, E., Martins, R.} } @article {Martins20092699, title = {Nanostructured silicon and its application to solar cells, position sensors and thin film transistors}, journal = {Philosophical Magazine}, volume = {89}, number = {28-30}, year = {2009}, note = {

cited By 37

}, pages = {2699-2721}, abstract = {

This paper reports the performance of small area solar cells, 128 linear integrated position sensitive detector arrays and thin film transistors based on nanostructured silicon thin films produced by plasma-enhanced chemical vapour deposition technique, close to the onset of dusty plasma conditions, within the transition region from amorphous to microcrystalline. The small area solar cells, produced in a modified single chamber reactor, exhibited very good electrical characteristics with a conversion efficiency exceeding 9\%. The 128 integrated position sensitive detector arrays, based on a similar pin structure, allow real-time 3D object imaging with a resolution higher than 90 l p/mm. The thin film transistors produced exhibited field effect mobility of 2.47 cm 2/V/s, threshold voltage of 2 V, on/off ratio larger than 10 7 and sub-threshold slopes of 0.32 V/decade, which are amongst the best results reported for this type of device. {\textcopyright} 2009 Taylor \& Francis.

}, doi = {10.1080/14786430902886910}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-73649119731\&partnerID=40\&md5=aa36e8f33e0cb7f0f2a553f76e5bd78f}, author = {Martins, R.a , Raniero, L.b , Pereira, L.a , Costa, D.a c , Aguas, H.a , Pereira, S.a , Silva, L.a , Goncalves, A.a , Ferreira,} } @article {Pereira20102938, title = {Nanostructured silicon based thin film transistors processed in the plasma dark region}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {10}, number = {4}, year = {2010}, note = {

cited By 1

}, pages = {2938-2943}, abstract = {

Nanostructured silicon (na-Si:H) thin films were fabricated using plasma enhanced chemical vapour deposition (PECVD) technique under high silane hydrogen dilution and a discharge frequency of 27 MHz, where the substrate was located in the dark region of the plasma, protected by a grounded metal grid. By not exposing the growth surface directly to the plasma we avoid the silicon growth surface to sustain a high ion bombardment leading to a less defective surface and highly compact films. The intrinsic films grown under these conditions were used to produce the channel region of thin film transistors (TFTs) with a bottom gate staggered configuration, integrating different dielectric layers. The devices produced exhibit a field effect mobility close to 1.84 cm 2 V -1S -1, threshold voltage around 2 V, on/off ratio above 10 7 and sub-threshold slope below 0.5 V/decade, depending on the dielectric used. Copyright {\textcopyright} 2010 American Scientific Publishers All rights reserved.

}, doi = {10.1166/jnn.2010.1443}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77954960967\&partnerID=40\&md5=3ca91c961d774ffa0f5ccf6c883e790a}, author = {Pereira, L., {\'A}guas, H., Gomes, L., Barquinha, P., Fortunato, E., Martins, R.} } @article {Seiroco200292, title = {New adhesion process based on lead-free solder applied in electronic power devices}, journal = {Key Engineering Materials}, volume = {230-232}, year = {2002}, note = {

cited By 0

}, pages = {92-95}, abstract = {

The aim of this paper is to present a set of electric data concerning the performances before and after ageing of Cu-Sn-Cu joins used to solder power diodes and to compare the results achieved with the ones obtained in diodes soldered using the conventional technology. The set of results achieved show that the Cu-Sn-Cu joins present even better performances than the ones exhibited by diodes soldered using the conventional technology, without requiring the use of Mo discs to be inserted between the silicon crystal and the metal contacts (stud or finger) to compensate thermal mismatches.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17544404371\&partnerID=40\&md5=ca2d573b8fbc48290036d2693ea0ff3e}, author = {Seiroco, H., Vincente, M., Ferreira, J., Fernandes, F.B., Marv{\~a}o, A.P., Martins, J.I., Fortunato, E., Martins, R.} } @article {Fortunato2008348, title = {New amorphous oxide semiconductor for thin film transistors (TFTs)}, journal = {Materials Science Forum}, volume = {587-588}, year = {2008}, note = {

cited By 1

}, pages = {348-352}, abstract = {

Thin film transistors (TFTs) have been produced by rf magnetron sputtering at room temperature, using non conventional oxide materials like amorphous indium-zinc-oxide (IZO) semiconductor, for the channel as well as for the drain and source regions. The obtained TFTs operate in the enhancement mode with threshold voltages of 2.4 V, saturation mobility of 22.7 cm2/Vs, gate voltage swing of 0.44 V/dec and an ON/OFF current ratio of 7{\texttimes}10 7. The high performances presented by these TFTs associated to a high electron mobility, at least two orders of magnitude higher than that of conventional amorphous silicon TFTs and a low threshold voltage, opens new doors for applications in flexible, wearable, disposable portable electronics as well as battery-powered applications.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-60349098168\&partnerID=40\&md5=f30555d6733ceafff3d365b05e08f6f1}, author = {Fortunato, E., Barquinha, P., Gon{\c c}alves, G., Pereira, L., Martins, R.} } @article {Assun{\c c}{\~a}o2003102, title = {New challenges on gallium-doped zinc oxide films prepared by r.f. magnetron sputtering}, journal = {Thin Solid Films}, volume = {442}, number = {1-2}, year = {2003}, note = {

cited By 71

}, pages = {102-106}, abstract = {

Gallium-doped zinc oxide films were prepared by r.f. magnetron sputtering at room temperature as a function of the substrate-target distance. The best results were obtained for a distance of 10 cm, where a resistivity as low as 2. 7 {\texttimes} 10-4 Ω cm, a Hall mobility of 18 cm2/Vs and a carrier concentration of 1.3 {\texttimes} 1021 cm-3 were achieved. The films are polycrystalline presenting a strong crystallographic c-axis orientation (002) perpendicular to the substrate. The films present an overall transmittance in the visible part of the spectra of approximately 85\%, on average. {\textcopyright} 2003 Elsevier B.V. All rights reserved.

}, doi = {10.1016/S0040-6090(03)00955-6}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0141525129\&partnerID=40\&md5=70f6a050320b65f5868947c120b7f6ab}, author = {Assun{\c c}{\~a}o, V., Fortunato, E., Marques, A., Gon{\c c}alves, A., Ferreira, I., {\'A}guas, H., Martins, R.} } @article {Fortunato200420, title = {New developments in gallium doped zinc oxide deposited on polymeric substrates by RF magnetron sputtering}, journal = {Surface and Coatings Technology}, volume = {180-181}, year = {2004}, note = {

cited By 46

}, pages = {20-25}, abstract = {

Gallium-doped zinc oxide (GZO) thin films have been deposited onto polyethylene naphthalate (PEN) substrates by r.f. magnetron sputtering at room temperature. The influence of the film thickness (from 70 to 890 nm) on the electrical, structural and morphological properties are presented. The lowest resistivity obtained was 5 {\texttimes} 10-4 Ω cm with a Hall mobility of 13.7 cm2/Vs and a carrier concentration of 8.6 {\texttimes} 1020 cm-3. These values were obtained by passivating the surface of the polymer with a thin silicon dioxide, so preventing the moisture and oxygen permeation inside the film. {\textcopyright} 2003 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.surfcoat.2003.10.025}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17044451049\&partnerID=40\&md5=c51a0b07c7f97bde1ababb1216b0a526}, author = {Fortunato, E.a , Gon{\c c}alves, A.a , Marques, A.a , Viana, A.b , {\'A}guas, H.a , Pereira, L.a , Ferreira, I.a , Vilarinho, P.c , Marti} } @article {Malik1998102, title = {A new high ultraviolet sensitivity FTO-GaP Schottky photodiode fabricated by spray pyrolysis}, journal = {Semiconductor Science and Technology}, volume = {13}, number = {1}, year = {1998}, note = {

cited By 9

}, pages = {102-107}, abstract = {

A new high quantum efficiency gallium phosphide Schottky photodiode has been developed by spray deposition of heavily doped tin oxide films on n-type epitaxial structures, as an alternative to the conventional Schottky photodiodes using a semitransparent gold electrode. It is shown that fluorine-doped tin oxide films are more effective as transparent electrodes than tin-doped indium oxide films. The proposed photodiodes have a typical responsivity near 0.33 A W-1 at 440 nm and an unbiased internal quantum efficiency close to 100\%, in the range from 250 to 450 nm. The model used to calculate the internal quantum efficiency (based on the optical constants of tin oxide films and gallium phosphide epitaxial layers) is found to be in good agreement with the experimental results. The data show that the quantum efficiency is strongly dependent on the thickness of the transparent electrode, owing to optical interference effects. The noise equivalent power for 440 nm is 2.7 {\texttimes} 10-15 W Hz-1/2, which indicates that these photodiodes can be used for accurate measurements in the short-wavelength range, even in the presence of stronger infrared background radiation.

}, doi = {10.1088/0268-1242/13/1/016}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0009685186\&partnerID=40\&md5=df361853e099a904f61fa79339f32e66}, author = {Malik, A.a , S{\^e}co, A.a , Fortunato, E.a , Martins, R.a , Shabashkevich, B.b , Piroszenko, S.b} } @article {Brida20021272, title = {New insights on large area flexible position sensitive detectors}, journal = {Journal of Non-Crystalline Solids}, volume = {299}, number = {302}, year = {2002}, note = {

cited By 18

}, pages = {1272-1276}, abstract = {

In this paper we present an improved version of large area (5 mm {\texttimes} 80 mm) flexible position sensitive detectors deposited on polyimide (Kapton{\textregistered} VN) substrates with 75 μm thickness, produced by plasma enhanced chemical vapor deposition (PECVD). The structures presented by the sensors are Kapton/ZnO:Al/(pin)a-Si:H/Al and the heterostructure Kapton/Cr/(in)a-Si:H/ZnO:Al. These sensors were characterized by spectral response, photocurrent dependence as a function of light intensity and position detectability measurements. The set of data obtained on one-dimensional position sensitive detectors based on the heterostructure show excellent performances with a maximum spectral response of 0.12 A/W at 500 nm and a non-linearity of {\textpm}10\%. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0022-3093(01)01092-4}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036531810\&partnerID=40\&md5=499a96a804ae146864c5caf1a6304459}, author = {Brida, D., Fortunato, E., {\'A}guas, H., Silva, V., Marques, A., Pereira, L., Ferreira, I., Martins, R.} } @article {Fortunato1998244, title = {New materials for large-area position-sensitive detectors}, journal = {Sensors and Actuators, A: Physical}, volume = {68}, number = {1-3}, year = {1998}, note = {

cited By 2

}, pages = {244-248}, abstract = {

Large-area thin-film position-sensitive detectors (TFPSDs) using the hydrogenated amorphous silicon (a-Si:H) technology are presented. The detection accuracy of these devices (lengths of about 80 mm) is better than {\textpm}0.5\% of the value of the full scale of the sensor, the spatial resolution is better than {\textpm}20 μm, the non-linearities measured are below {\textpm}2\% and the frequency response is in the range of a few kilohertz, compatible with the sampling frequency of most electromechanical assembling/control systems. The obtained results are quite promising regarding the application of these sensors to a wide variety of optical inspection systems. {\textcopyright} 1998 Elsevier Science S.A. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0041636203\&partnerID=40\&md5=62e473216c3f92e9a90188b70e958756}, author = {Fortunato, E., Martins, R.} } @article {Fortunato1998244, title = {New materials for large-area position-sensitive detectors}, journal = {Sensors and Actuators, A: Physical}, volume = {68}, number = {1 -3 pt 2}, year = {1998}, note = {

cited By 8

}, pages = {244-248}, abstract = {

Large-area thin-film position-sensitive detectors (TFPSDs) using the hydrogenated amorphous silicon (a-Si:H) technology are presented. The detection accuracy of these devices (lengths of about 80 mm) is better than {\textpm}0.5\% of the value of the full scale of the sensor, the spatial resolution is better than {\textpm}20 μm, the non-linearities measured are below {\textpm}2\% and the frequency response is in the range of a few kilohertz, compatible with the sampling frequency of most electromechanical assembling/control systems. The obtained results are quite promising regarding the application of these sensors to a wide variety of optical inspection systems.

}, doi = {10.1016/S0924-4247(98)00012-0}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032095239\&partnerID=40\&md5=dfbd25d3e3f2269f3ce8485c0ef55357}, author = {Fortunato, Elvira, Martins, Rodrigo} } @article {Gon{\c c}alves199970, title = {New metallurgical systems for electronic soldering applications}, journal = {Sensors and Actuators, A: Physical}, volume = {74}, number = {1}, year = {1999}, note = {

cited By 4

}, pages = {70-76}, abstract = {

The aim of this paper is to present results on a new soldering process based on the low-temperature solidification of intermetallic phases from the system Cu-Sn-Cu which can be employed to form a heat-resistant die-attach as well as signal and power electric contacts. Because of the total transformation into intermetallic phase, the working temperature of the bond formed is several hundred degrees Celsius higher than the process temperature (around 250{\textdegree}C). This process leads to a homologous temperature T/Tm of about 0.3 compared to 0.7 in the case of soft SnAg solder alloy. Therefore a better reliability of the proposed bonding process is achievable. Results of the match of the predicted volume fraction of the intermetallic forms and the experimentally measured contact volume would be also discussed, for contacts formed in power diodes.

}, doi = {10.1016/S0924-4247(98)00305-7}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0344578023\&partnerID=40\&md5=246f30860192512786eabaef5a18498f}, author = {Gon{\c c}alves, C.a , Ferreira, J.a , Fortunato, E.a , Ferreira, I.a , Martins, R.a , Marv{\~a}o, A.P.e , Martins, J.I.b , Harder, T.c ,} } @article {Martins2000263, title = {New nanostructured silicon films grown by pecvd technique under controlled powder formation conditions}, journal = {Solar Energy}, volume = {69}, year = {2000}, note = {

cited By 5

}, pages = {263-269}, abstract = {

In this paper the influence of the DC grid bias on the plasma impedance and the I-V behaviour of silane plasmas used to grow undoped amorphous silicon films by plasma enhanced chemical vapour deposition technique using a triode configuration at or close to the powder regime is studied. The aim is to determine the correlation between the r.f. power and the DC grid voltage with the plasma parameters, under isothermal gas conditions. The results should lead to the production of nanostructured films, with the required optoelectronic characteristics for photovoltaic applications. The results achieved show the existence of a boundary region close to the γ-regime (powder formed) where nanoparticles can be formed by moderated ion bombardment of the growing surface. This is characterised by the plasma resistance of the same order of magnitude of the plasma reactance. Under this condition, it is possible to grow amorphous silicon films that can incorporate nanoparticles, exhibiting photosensitivities of about 107 (two orders of magnitude larger than the one exhibited by films grown under conventional conditions) with densities of states determined by the constant photocurrent method below 3 {\texttimes} 1015 cm3. Apart from that, the growth of the films is less affected by light soaking than the conventional films grown by standard techniques. {\textcopyright} 2001 Elsevier Science Ltd. All rights reserved.

}, doi = {10.1016/S0038-092X(01)00060-3}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034428230\&partnerID=40\&md5=21369cfc1f8d467eacbe4f937c3b8d73}, author = {Martins, R., {\'A}guas, H., Cabrita, A., Tonello, P., Silva, V., Ferreira, I., Portunato, E., Guimares, L.} } @article {Martins2001170, title = {New steps to improve a-Si:H device stability by design of the interfaces}, journal = {Advanced Engineering Materials}, volume = {3}, number = {3}, year = {2001}, note = {

cited By 0

}, pages = {170-173}, abstract = {n/a}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035530158\&partnerID=40\&md5=6acdc136ae6a0765bed29a7c0eff308f}, author = {Martins, R., Ferreira, I., Cabrita, A., {\'A}guas, H., Silva, V., Fortunato, E.} } @article {Fortunate20001213, title = {New ultra-light flexible large area thin film position sensitive detector based on amorphous silicon}, journal = {Journal of Non-Crystalline Solids}, volume = {266-269 B}, year = {2000}, note = {

cited By 16

}, pages = {1213-1217}, abstract = {

In this paper we report on large area one dimensional (1D) amorphous silicon position sensors deposited on flexible polymer foil substrate. The pin sensor structure was deposited by rf plasma enhanced chemical vapour deposition (PECVD). For the electrical and optical characterisation the sensors have been mounted on a convex holder with a 14-mm radius-of-curvature, since the main goal of this work is to develop a flexible position sensor to be incorporated in a micromotor in order to measure its angular velocity continuously. The obtained sensors present adequate performances concerning the position non-linearity ({\textpm}1\% in 20 mm length), comparable to those fabricated on glass substrates. {\textcopyright} 2000 Elsevier Science B.V. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001406698\&partnerID=40\&md5=9fc7bf560273227d05035dfdafb4584e}, author = {Fortunate, E.a , Ferreira, I.a , Giuliani, F.a , Wurmsdobler, P.b , Martins, R.a} } @article {Malik199868, title = {New UV-enhanced solar blind optical sensors based on monocrystalline zinc sulphide}, journal = {Sensors and Actuators, A: Physical}, volume = {67}, number = {1-3}, year = {1998}, note = {

cited By 3

}, pages = {68-71}, abstract = {

UV-enhanced monocrystalline zinc sulphide optical sensors with high quantum efficiency have been developed by spray deposition of heavy fluorine-doped tin oxide (FTO) thin films onto the surface of zinc sulphide monocrystals as an alternative to the UV-enhanced high-efficiency silicon photodetectors commonly used in precise radiometric and spectroscopic measurements as well as to new sensors based on SiC and GaN. The fabricated sensors have an unbiased internal quantum efficiency that is nearly 100\% from 250 to 320 nm, and the typical sensitivity at 250 nm is 0.15 A W-1. The sensors are insensitive to solar radiation in conditions on the earth and can be used as solar blind photodetectors for precision UV measurements under direct solar illumination for both terrestrial and space applications. {\textcopyright} 1998 Elsevier Science S.A. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0042284308\&partnerID=40\&md5=49da61c37432e34ade99df8e957feec6}, author = {Malik, A.a , S{\^e}co, A.b , Fortunato, E.a , Martins, R.a} } @article {Malik199868, title = {New UV-enhanced solar blind optical sensors based on monocrystalline zinc sulphide}, journal = {Sensors and Actuators, A: Physical}, volume = {67}, number = {1 -3 pt 1}, year = {1998}, note = {

cited By 11

}, pages = {68-71}, abstract = {

UV-enhanced monocrystalline zinc sulphide optical sensors with high quantum efficiency have been developed by spray deposition of heavy fluorine-doped tin oxide (FTO) thin films onto the surface of zinc sulphide monocrystals as an alternative to the UV-enhanced high-efficiency silicon photodetectors commonly used in precise radiometric and spectroscopic measurements as well as to new sensors based on SiC and GaN. The fabricated sensors have an unbiased internal quantum efficiency that is nearly 100\% from 250 to 320 nm, and the typical sensitivity at 250 nm is 0.15 A W-1. The sensors are insensitive to solar radiation in conditions on the earth and can be used as solar blind photodetectors for precision UV measurements under direct solar illumination for both terrestrial and space applications.

}, doi = {10.1016/S0924-4247(97)01740-8}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032072503\&partnerID=40\&md5=aca7934cae8c9e5dab2c5edabab2e06f}, author = {Malik, A., Seco, A., Fortunate, E., Martins, R.} } @article {Pereira2006275, title = {Nickel-assisted metal-induced crystallization of silicon: Effect of native silicon oxide layer}, journal = {Thin Solid Films}, volume = {511-512}, year = {2006}, note = {

cited By 12

}, pages = {275-279}, abstract = {

This work focuses on the role of the native oxide layer (SiO2) on the nickel (Ni)-assisted crystallization of amorphous silicon (a-Si). In some samples, the native oxide was removed using a HF-diluted solution before Ni layers with 0.5 nm be deposited on a-Si. The results show that the presence of a thin SiO2 layer of about 3 nm between the a-Si and the Ni delays the crystallization process. Ellipsometry data show that, after annealing for 5 h at 500 {\textdegree}C, the HF-cleaned sample presents a crystalline fraction of 88\%, while the one with the native oxide has only 35\%. This difference disappears after 20 h where both samples present similar crystalline fraction. These facts are also reflected on the film{\textquoteright}s electrical properties, where the activation energy for samples annealed for 5 h rises from 0.42 eV to 0.55 eV, when the oxide layer is removed. After 20 h and 30 h, the activation energy is around 0.55 eV for both kinds of samples, meaning that films with similar electrical properties are now obtained. However, the XRD data suggest the presence of some structural differences attributed to slight differences on the crystallization process. {\textcopyright} 2005 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2005.12.005}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33747381628\&partnerID=40\&md5=9c77b598d31fa92acfa2a31c933ec5f7}, author = {Pereira, L.a , Martins, R.M.S.b , Schell, N.b , Fortunato, E.a , Martins, R.a} } @article {Santos2006868, title = {Novel multilayer coatings on polyethylene for acetabular devices}, journal = {Materials Science Forum}, volume = {514-516}, number = {PART 2}, year = {2006}, note = {

cited By 0

}, pages = {868-871}, abstract = {

Total hip replacement is a common practice in every day clinical work. Artificial hip implants consist of a femoral component and an acetabular component. Nowadays the acetabular component is composed of a polymeric cup and a metallic shell. This study focuses the development of an innovative acetabular component substituting the metallic shell by a multilayer coating on the acetabular cup. A titanium coating was deposited onto ultra-high molecular weight polyethylene (UHMWPE) samples by physical vapour deposition (PVD), having an in situ pre-treatment with argon ion bombardment in order to optimize the adhesive strength by surface modification, followed by the deposition of a thin film of hydroxyapatite (HA) using rf magnetron sputtering technique, at room temperature. Results obtained seem to indicate that these multilayer coatings can be a viable alternative to the metallic shell, leading to the substitution of a two part for a one part acetabular component.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-37849006396\&partnerID=40\&md5=dfab01737b3b706fe596017cf34854a1}, author = {Santos, V.a , Borges, J.P.a , Ranito, C.M.S.b , Pires, E.b , Ara{\'u}jo, H.b , Marques, A.a , Tom{\'a}s, L.a , Fortunato, E.a , Martins,} } @article {Fernandes2004357, title = {Novel structure for large area image sensing}, journal = {Sensors and Actuators, A: Physical}, volume = {115}, number = {2-3 SPEC. ISS.}, year = {2004}, note = {

cited By 2

}, pages = {357-361}, abstract = {

This work presents preliminary results in the study of a novel structure for a laser scanned photodiode (LSP) type of image sensor. In order to increase the signal output, a stacked p-i-n-p-i-n structure with an intermediate light-blocking layer is used. The image and the scanning beam are incident through opposite sides of the sensor and their absorption is kept in separate junctions by an intermediate light-blocking layer. As in the usual LSP structure the scanning beam-induced photocurrent is dependent on the local illumination conditions of the image. The main difference between the two structures arises from the fact that in this new structure the image and the scanner have different optical paths leading to an increase in the photocurrent when the scanning beam is incident on a region illuminated on the image side of the sensor, while a decreasing in the photocurrent was observed in the single junction LSP. The results show that the structure can be successfully used as an image sensor even though some optimization is needed to enhance the performance of the device. {\textcopyright} 2004 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.sna.2004.03.076}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-4544310162\&partnerID=40\&md5=857d4974979b8d01e89c26520fde1247}, author = {Fernandes, M.a , Vieira, M.a , Martins, R.b} } @article {Panigrahi20166139, title = {Observation of Space Charge Dynamics Inside an All Oxide Based Solar Cell}, journal = {ACS Nano}, volume = {10}, number = {6}, year = {2016}, note = {

cited By 0

}, pages = {6139-6146}, abstract = {

The charge transfer dynamics at interfaces are fundamental to know the mechanism of photovoltaic processes. The internal potential in solar cell devices depends on the basic processes of photovoltaic effect such as charge carrier generation, separation, transport, recombination, etc. Here we report the direct observation of the surface potential depth profile over the cross-section of the ZnO nanorods/Cu2O based solar cell for two different layer thicknesses at different wavelengths of light using Kelvin probe force microscopy. The topography and phase images across the cross-section of the solar cell are also observed, where the interfaces are well-defined on the nanoscale. The potential profiling results demonstrate that under white light illumination, the photoinduced electrons in Cu2O inject into ZnO due to the interfacial electric field, which results in the large difference in surface potential between two active layers. However, under a single wavelength illumination, the charge carrier generation, separation, and transport processes between two active layers are limited, which affect the surface potential images and corresponding potential depth profile. Because of changes in the active layer thicknesses, small variations have been observed in the charge carrier transport mechanism inside the device. These results provide the clear idea about the charge carrier distribution inside the solar cell in different conditions and show the perfect illumination condition for large carrier transport in a high performance solar cell. {\textcopyright} 2016 American Chemical Society.

}, doi = {10.1021/acsnano.6b02090}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976603541\&partnerID=40\&md5=bf888bc0b4e4180496603e812fa7c38a}, author = {Panigrahi, S., Calmeiro, T., Martins, R., Nunes, D., Fortunato, E.} } @article {Marques2015, title = {Office paper platform for bioelectrochromic detection of electrochemically active bacteria using tungsten trioxide nanoprobes}, journal = {Scientific Reports}, volume = {5}, year = {2015}, note = {

cited By 2

}, abstract = {

Electrochemically active bacteria (EAB) have the capability to transfer electrons to cell exterior, a feature that is currently explored for important applications in bioremediation and biotechnology fields. However, the number of isolated and characterized EAB species is still very limited regarding their abundance in nature. Colorimetric detection has emerged recently as an attractive mean for fast identification and characterization of analytes based on the use of electrochromic materials. In this work, WO 3 nanoparticles were synthesized by microwave assisted hydrothermal synthesis and used to impregnate non-treated regular office paper substrates. This allowed the production of a paper-based colorimetric sensor able to detect EAB in a simple, rapid, reliable, inexpensive and eco-friendly method. The developed platform was then tested with Geobacter sulfurreducens, as a proof of concept. G. sulfurreducens cells were detected at latent phase with an RGB ratio of 1.10 {\textpm} 0.04, and a response time of two hours.

}, doi = {10.1038/srep09910}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84928138787\&partnerID=40\&md5=ef70506b82febbfb1891c965ec8af0ff}, author = {Marques, A.C.a c , Santos, L.a , Costa, M.N.a b , Dantas, J.M.c , Duarte, P.a , Gon{\c c}alves, A.a , Martins, R.a , Salgueiro, C.A.c} } @article {Ma{\c c}arico19961207, title = {On the a-Si:H film growth: The role of the powder formation}, journal = {Journal of Non-Crystalline Solids}, volume = {198-200}, number = {PART 2}, year = {1996}, note = {

cited By 6

}, pages = {1207-1211}, abstract = {

Results are presented which are geared towards an understanding of the influence of powder formation during film growth. Plasma chemistry is correlated with the morphology, structure (inferred through infrared spectroscopy, scanning electron microscopy and X-ray diffraction) electro-optical and density of states of intrinsic films deposited under continuous and power modulated operation. Results show that for modulation frequencies where no powder formation occurs and low substrate temperatures T (150{\textdegree}C), silane decomposition gives rise to the growth of inhomogeneous films while in the high modulation frequency regime, at the same temperature, the anions and powder are trapped resulting in films with high deposition rates and low defect density.

}, doi = {10.1016/0022-3093(96)00181-0}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-18344400044\&partnerID=40\&md5=2e1a5dbde4f017e5d9feafd08d540ca1}, author = {Ma{\c c}arico, A.a , Vieira, M.a , Fantoni, A.a , Louro, P.a , S{\^e}co, A.a , Martins, R.a , Hollenstein, C.b} } @article {Willeke199179, title = {On the structural, optical and electronic properties of microcrystalline Si:O:C:H thin films prepared in a two-consecutive-decomposition-deposition-chamber system}, journal = {Philosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties}, volume = {63}, number = {1}, year = {1991}, note = {

cited By 8

}, pages = {79-86}, abstract = {

P- and n-type weakly absorbing highly conductive (σ\>0{\textperiodcentered}1Ω-1 cm-1) SiC thin films with similar structural and optoelectronic properties have been prepared in a two-consecutive-decomposition-deposition-chamber reactor. These films are composed of Si microcrystals (δ = 50-100 {\r A}) embedded in an amorphous Si:0:C:H matrix, with concentrations up to 25at.\%O and 20at.\%C. From diffraction studies there is no evidence for the presence of SiC crystallites. Electrical conduction appears to be in extended states via percolation channels through Si crystallites of sufficient volume fraction. {\textcopyright} 1991 Taylor \& Francis Ltd.

}, doi = {10.1080/01418639108224431}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026021628\&partnerID=40\&md5=9d562c465a0044e4cc3a1a7e6401671e}, author = {Willeke, G.a c , Martins, R.b} } @article {Rodrigues201538, title = {One-step synthesis of ZnO decorated CNT buckypaper composites and their optical and electrical properties}, journal = {Materials Science and Engineering B: Solid-State Materials for Advanced Technology}, volume = {195}, year = {2015}, note = {

cited By 3

}, pages = {38-44}, abstract = {

ZnO/CNT composites were prepared using ZnO nanoparticles and tetrapods synthesized by the Laser Assisted Flow Deposition method. The co-operative behaviour between these two materials may give rise to the production of advanced functional materials with a wide range of applications in electronics and optoelectronics. Despite some degree of aggregation in the case of the nanoparticles, scanning electron microscopy images evidence that the produced ZnO structures are well dispersed in the CNT buckypapers. Independent of the ZnO morphology the samples resistivity was shown to be of the order of \~{}10-1 Ω cm while in the case of the electron mobility, the composite with tetrapods reveals a lower value than the ones obtained for the remaining samples. Well-structured ZnO luminescence was observed mainly in ultraviolet highlighting the high optical quality of the produced structures. The temperature dependence of the luminescence reveals a distinct trend for the composites with ZnO tetrapods and ZnO nanoparticles. {\textcopyright} 2015 Elsevier B.V.

}, doi = {10.1016/j.mseb.2015.01.009}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84922732018\&partnerID=40\&md5=4b126d49d30cc8acfdafd2a7f4460b26}, author = {Rodrigues, J.a , Mata, D.a , Pimentel, A.b , Nunes, D.b , Martins, R.b , Fortunato, E.b , Neves, A.J.a , Monteiro, T.a , Costa,} } @article {Kiazadeh2015, title = {Operational stability of solution based zinc tin oxide/SiO2 thin film transistors under gate bias stress}, journal = {APL Materials}, volume = {3}, number = {6}, year = {2015}, note = {

cited By 1

}, abstract = {

In this study, we report solution-processed amorphous zinc tin oxide transistors exhibiting high operational stability under positive gate bias stress, translated by a recoverable threshold voltage shift of about 20\% of total applied stress voltage. Under vacuum condition, the threshold voltage shift saturates showing that the gate-bias stress is limited by trap exhaustion or balance between trap filling and emptying mechanism. In ambient atmosphere, the threshold voltage shift no longer saturates, stability is degraded and the recovering process is impeded. We suggest that the trapping time during the stress and detrapping time in recovering are affected by oxygen adsorption/desorption processes. The time constants extracted from stretched exponential fitting curves are \~{}106 s and 105 s in vacuum and air, respectively. {\textcopyright} 2015 Author(s).

}, doi = {10.1063/1.4919057}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84928798683\&partnerID=40\&md5=a8e41d42c2e7088639ac7020ca5aa364}, author = {Kiazadeh, A.a b , Salgueiro, D.a , Branquinho, R.a , Pinto, J.a , Gomes, H.L.b c , Barquinha, P.a , Martins, R.a , Fortunato, E.} } @article {Prabakaran2008308, title = {Optical and microstructural investigations of porous silicon coated with a-Si:H using PECVD technique}, journal = {Materials Science Forum}, volume = {587-588}, year = {2008}, note = {

cited By 0

}, pages = {308-312}, abstract = {

In the present work, the spectroscopic ellipsometry (1.5 - 5.5 eV) was used to investigate the effects of current density induced microstructural variations and their influence on the electronic states of as-prepared and a-Si:H coated porous silicon (PS). The pseudodielectric responses of the low and high current densities (5 and 40 mA/cm2) were analyzed using a multilayer model within the effective medium approximation. The FTIR investigation reveals me enhancement of surface oxide (Si-Ox) layer with current density and the improvement of the Si-Hx band after a-Si:H coating.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-60349088150\&partnerID=40\&md5=8b9a9ae7a8f49e0d3dc2a62f225a1dc8}, author = {Prabakaran, R., Aguas, H., Pereira, L., Elangovan, E., Fortunato, E., Martins, R., Ferreira, I.} } @article {Kholkin2002563, title = {Optical and photoelectric properties of PZT films for microelectronic applications}, journal = {Key Engineering Materials}, volume = {230-232}, year = {2002}, note = {

cited By 1

}, pages = {563-566}, abstract = {

PbZrxTi1-xO3 (PZT) films are currently being investigated in view of their large switching polarization and piezoelectric coefficients useful for various applications. Besides, PZT films possess large photosensitivity, which, in combination with the above listed properties, can be a base for future microelectronic applications including photostrictive actuators and optical storage devices. In this work, PZT thin films of several compositions (x=0.2 and 0.45) were deposited on Pt-coated Si and ITO/glass substrates via modified sol-gel technique. Microstructures of the films were evaluated using XRD, SEM and AFM. The optical transmission measurements on PZT films deposited on ITO/glass revealed a high transparency over 80\% and a band gap of about 3.4 eV. The observed photocurrent exhibited a maximum and was attributed to band-to-band optical transitions.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17144438002\&partnerID=40\&md5=8002e90c9e2c26c7ce45bc21757c6324}, author = {Kholkin, A.L., Iakovlev, S., Fortunato, E., Martins, R., Ferreira, I., Shvartsman, V., Baptista, J.L.} } @article {Prabakaran20078664, title = {Optical and structural analysis of porous silicon coated with GZO films using rf magnetron sputtering}, journal = {Thin Solid Films}, volume = {515}, number = {24 SPEC. ISS.}, year = {2007}, note = {

cited By 26

}, pages = {8664-8669}, abstract = {

In the production of porous silicon (PS) to optoelectronic application one of the most significant constrains is the surface defects passivation. In the present work we investigate, gallium-doped zinc oxide (GZO) thin films deposited by rf magnetron sputtering at room temperature on PS obtained with different etching times. The X-ray diffraction (XRD), Fourier transform infrared (FTIR) and atomic force microscopy (AFM) analysis have been carried out to understand the effect of GZO films coating on PS. Further, the XRD analysis suggests the formation of a good crystalline quality of the GZO films on PS. From AFM investigation we observe that the surface roughness increases after GZO film coating. The photoluminescence (PL) measurements on PS and GZO films deposited PS shows three emission peaks at around 1.9~eV (red-band), 2.78~eV (blue-band) and 3.2~eV (UV-band). PL enhancement in the blue and ultraviolet (UV) region has been achieved after GZO films deposition, which might be originated from a contribution of the near-band-edge recombination from GZO. {\textcopyright} 2007 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2007.03.098}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34648843175\&partnerID=40\&md5=4743bbf303b5782a450fd64a2da26949}, author = {Prabakaran, R.a , Monteiro, T.b , Peres, M.b , Viana, A.S.c , da Cunha, A.F.b , {\'A}guas, H.a , Gon{\c c}alves, A.a , Fortunato, E.a , M} } @article {Mei200211, title = {Optimisation of parameters for aqueous tape-casting of cordierite-based glass ceramics by Taguchi method}, journal = {Materials Science and Engineering A}, volume = {334}, number = {1-2}, year = {2002}, note = {

cited By 13

}, pages = {11-18}, abstract = {

Aqueous suspensions of cordierite-based glass ceramics were prepared by using four types of dispersants and binders and different solids loading. The experiments were designed according to the Taguchi method, which shows great advantages in optimising more than two factors that need to be considered in an experimental design. Different parameters such as the type and concentration of the dispersants and the binders, and the solids loading were optimised to obtain homogeneous and crack-free green tapes. Dolapix CE 64 (1.0 wt.\%) and Duramax B-1080 or Duramax B-1070 (10 wt.\%) with 65 wt.\% solids loading represent an optimal selection of the parameters to obtain low viscosity suspension, and crack-free green tapes with the highest green and sintered density. Microstructural differences between crack-free and cracked samples were observed by scanning electron microscopy (SEM). The crack-free green tapes show homogenous microstructures from top to bottom with organic additives uniformly surrounding the powders, whereas cracked samples exhibit heterogeneous microstructures and non-uniform distribution of the organics. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0921-5093(01)01773-7}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036721581\&partnerID=40\&md5=5a44657a40887a55ec9e8a57600dd16c}, author = {Mei, S.a , Yang, J.a , Ferreira, J.M.F.a , Martins, R.b} } @article {Fortunato20122945, title = {Oxide semiconductor thin-film transistors: A review of recent advances}, journal = {Advanced Materials}, volume = {24}, number = {22}, year = {2012}, note = {

cited By 771

}, pages = {2945-2986}, abstract = {

Transparent electronics is today one of the most advanced topics for a wide range of device applications. The key components are wide bandgap semiconductors, where oxides of different origins play an important role, not only as passive component but also as active component, similar to what is observed in conventional semiconductors like silicon. Transparent electronics has gained special attention during the last few years and is today established as one of the most promising technologies for leading the next generation of flat panel display due to its excellent electronic performance. In this paper the recent progress in n- and p-type oxide based thin-film transistors (TFT) is reviewed, with special emphasis on solution-processed and p-type, and the major milestones already achieved with this emerging and very promising technology are summarizeed. After a short introduction where the main advantages of these semiconductors are presented, as well as the industry expectations, the beautiful history of TFTs is revisited, including the main landmarks in the last 80 years, finishing by referring to some papers that have played an important role in shaping transparent electronics. Then, an overview is presented of state of the art n-type TFTs processed by physical vapour deposition methods, and finally one of the most exciting, promising, and low cost but powerful technologies is discussed: solution-processed oxide TFTs. Moreover, a more detailed focus analysis will be given concerning p-type oxide TFTs, mainly centred on two of the most promising semiconductor candidates: copper oxide and tin oxide. The most recent data related to the production of complementary metal oxide semiconductor (CMOS) devices based on n- and p-type oxide TFT is also be presented. The last topic of this review is devoted to some emerging applications, finalizing with the main conclusions. Related work that originated at CENIMAT|I3N during the last six years is included in more detail, which has led to the fabrication of high performance n- and p-type oxide transistors as well as the fabrication of CMOS devices with and on paper. Transparent electronics is one of the most advanced science topics for a broad range of device applications. In this article an overview is presented of state-of-the-art n- and p-type oxides for TFTs and their integration, processed by physical vapor deposition and by solution processing techniques. Some of the most relevant emerging applications are also presented, including CMOS devices based on oxide TFTs fabricated on glass and even on paper. Copyright {\textcopyright} 2012 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/adma.201103228}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84861829395\&partnerID=40\&md5=859bb17bd1047ad0751bfeda274d9358}, author = {Fortunato, E., Barquinha, P., Martins, R.} } @article {Fortunato20092741, title = {Oxide semiconductors: Order within the disorder}, journal = {Philosophical Magazine}, volume = {89}, number = {28-30}, year = {2009}, note = {

cited By 23

}, pages = {2741-2758}, abstract = {

The effect is considered of order and disorder on the electrical and optical performance of ionic oxide semiconductors used to produce optoelectronic devices such as p-n heterojunction solar cells and thin-film transistors (TFTs). The results obtained show that p-type c-Si/a-IZO/poly-ZGO solar cells exhibit efficiencies above 14\% in device areas of about 2.34 cm2, whereas amorphous oxide TFTs based on the Ga-Zn-Sn-O system demonstrate superior performance to the polycrystalline ZnO TFTs, with ION/I OFF ratio exceeding 107, turn-on voltage below 1-2 V and saturation mobility above 25 cm2 V-1 s-1. In addition, preliminary data on a p-type oxide TFT based on the Zn-Cu-O system are presented. {\textcopyright} 2009 Taylor \& Francis.

}, doi = {10.1080/14786430903022671}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-76849098010\&partnerID=40\&md5=9a8234a50a604e699e9326c04e7434ec}, author = {Fortunato, E., Pereira, L., Barquinha, P., Ferreira, I., Prabakaran, R., Gon{\c c}alves, G., Gon{\c c}alves, A., Martins, R.} } @article {Figueiredo201241, title = {P-Type Cu x films deposited at room temperature for thin-film transistors}, journal = {IEEE/OSA Journal of Display Technology}, volume = {8}, number = {1}, year = {2012}, note = {

cited By 14

}, pages = {41-47}, abstract = {

Thin-films of copper oxide Cu x were sputtered from a metallic copper (Cu) target and studied as a function of oxygen partial pressure. A metallic Cu film with cubic structure obtained from 0\% O PP has been transformed to cubic Cu x phase for the increase in O PP to 9\% but then changed to monoclinic CuO phase (for. The variation in crystallite size (calculated from x-ray diffraction data) was further substantiated by the variation in grain size (surface microstructures). The Cu x films produced with O PP ranging between 9\% and 75\% showed p-type behavior, which were successfully applied to produce thin-film transistors. {\textcopyright} 2006 IEEE.

}, doi = {10.1109/JDT.2011.2170153}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84855429944\&partnerID=40\&md5=29ebce203d7e077623825f441f580505}, author = {Figueiredo, V.a , Elangovan, E.a , Barros, R.a b , Pinto, J.V.a , Busani, T.a , Martins, R.a , Fortunato, E.a} } @article {Figueiredo2013735, title = {P-Type CuxO thin-film transistors produced by thermal oxidation}, journal = {IEEE/OSA Journal of Display Technology}, volume = {9}, number = {9}, year = {2013}, note = {

cited By 9

}, pages = {735-740}, abstract = {

Thin-films of copper oxide Cu O were produced by thermal oxidation of metallic copper (Cu) at different temperatures (150-450 C). The films produced at temperatures of 200, 250 and 300 C showed high Hall motilities of 2.2, 1.9 and 1.6 cm V s , respectively. Single Cu O phases were obtained at 200 C and its conversion to CuO starts at 250 C. For lower thicknesses 40 nm, the films oxidized at 250 C showed a complete conversion to CuO phase. Successful thin-film transistors (TFTs) were produce by thermal oxidation of a 20 nm Cu film, obtaining p-type Cu O (at 200 C) and CuO (at 250 C) with On/Off ratios of 6 10 and 1 10 , respectively. {\textcopyright} 2005-2012 IEEE.

}, doi = {10.1109/JDT.2013.2247025}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84884285102\&partnerID=40\&md5=b1c9d891450c1d2de998cc8ac0b0c7c2}, author = {Figueiredo, V.a b , Pinto, J.V.a b , Deuermeier, J.a b , Barros, R.a b , Alves, E.c , Martins, R.a b , Fortunato, E.a b} } @article {Golshahi20091149, title = {P-type ZnO thin film deposited by spray pyrolysis technique: The effect of solution concentration}, journal = {Thin Solid Films}, volume = {518}, number = {4}, year = {2009}, note = {

cited By 41

}, pages = {1149-1152}, abstract = {

The aim of this research is to study the role of concentration variations on precursor solution of nitrogen doped ZnO (ZnO:N) thin films which has been prepared by spray pyrolysis technique. SEM micrographs show that ZnO:N films in 0.1~ML concentration have a mono-disperse surface with nano-spheres of 50~nm in diameter. In higher molarities the nano-spheres agglomerate leading to particle formation. For 0.4~ML concentrations this change is observed, where plume like particles are seen over the surface of ZnO:N thin film. This change corresponds also to changes observed in the XRD spectra, where crystal orientation of ZnO:N thin films changes from (002) to (100). All of the ZnO:N thin films have kept their sharp ultra violet absorption edge, but the transparency in visible spectra region decreases as the molarities in precursor solution increase. Photoluminescence spectra at room temperature revealed emissions at 2.33~eV, 2.54~eV and 3.16~eV that can be attributed to the presence of nitrogen in ZnO structure. We also observe that all samples analyzed show a p-type Hall effect behavior, and that as the molarities in the precursor solution increase, the electrical resistivity of the films decreases, due to an enhancement of free carriers, while the mobility decreases. These data prove the capability of spray pyrolysis as a viable technique in preparing p-type TCO materials and so, fully transparent CMOS-like devices. {\textcopyright} 2009 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2009.04.074}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-71649112209\&partnerID=40\&md5=8fb4f897cd7d16d52ae5472e103c82ff}, author = {Golshahi, S.a , Rozati, S.M.a , Martins, R.b , Fortunato, E.b} } @article {Courteille19962069, title = {Particle agglomeration study in in silane plasmas: In situ study by polarization-sensitive laser light scattering}, journal = {Journal of Applied Physics}, volume = {80}, number = {4}, year = {1996}, note = {

cited By 85

}, pages = {2069-2078}, abstract = {

To determine self-consistently the time evolution of particle size and their number density in situ multi-angle polarization-sensitive laser light scattering was used. Cross-polarization intensities (incident and scattered light intensities with opposite polarization) measured at 135{\textdegree} and ex situ transmission electronic microscopy analysis demonstrate the existence of nonspherical agglomerates during the early phase of agglomeration. Later in the particle time development both techniques reveal spherical particles again. The presence of strong cross-polarization intensities is accompanied by low-frequency instabilities detected on the scattered light intensities and plasma emission. It is found that the particle radius and particle number density during the agglomeration phase can be well described by the Brownian free molecule coagulation model. Application of this neutral particle coagulation model is justified by calculation of the particle charge whereby it is shown that particles of a few tens of nanometer can be considered as neutral under our experimental conditions. The measured particle dispersion can be well described by a Brownian free molecule coagulation model including a log-normal particle size distribution. {\textcopyright} 1996 American Institute of Physics.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001314405\&partnerID=40\&md5=b4e5d5dc63519f1f845a7529f72c1f66}, author = {Courteille, C.a , Hollenstein, Ch.a , Dorier, J.-L.a , Gay, P.a , Schwarzenbach, W.a , Howling, A.A.a , Bertran, E.b , Viera, G.} } @article {Oliveira2016430, title = {A path to renewable Mg reduction from MgO by a continuous-wave Cr:Nd:YAG ceramic solar laser}, journal = {Solar Energy Materials and Solar Cells}, volume = {155}, year = {2016}, note = {

cited By 0

}, pages = {430-435}, abstract = {

The first successful ablation of magnesium oxide through a home-made continuous-wave Cr:Nd:YAG ceramic solar laser is reported. A stationary heliostat-parabolic mirror solar energy collection and concentration system was used. A stable continuous-wave laser output power of 19.2 W was attained with laser beam brightness figure of merit 7.6 times higher than that of the previous scheme, enabling therefore the direct ablation of pure magnesium by our solar-pumped laser with only 1.6 m2 effective collection area. This could be an important step towards renewable magnesium production, offering multiple advantages, such as reducing agent avoidance, in relation to that of the previous Fresnel lens Cr:Nd:YAG continuous-wave solar laser system. {\textcopyright} 2016 Elsevier B.V.

}, doi = {10.1016/j.solmat.2016.06.046}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978107440\&partnerID=40\&md5=ddcf3b028515208d878b25cc495f0b62}, author = {Oliveira, M.a , Liang, D.a , Almeida, J.a , Vistas, C.R.a , Gon{\c c}alves, F.a , Martins, R.b} } @article {Barquinha2009, title = {Performance and stability of low temperature transparent thin-film transistors using barrieramorphous multicomponent dielectrics}, journal = {Journal of the Electrochemical Society}, volume = {156}, number = {11}, year = {2009}, note = {

cited By 35

}, pages = {H824-H831}, abstract = {

High performance transparent thin-film transistors deposited on glass substrates and entirely processed at a low temperature not exceeding 150{\textdegree}C are presented and analyzed in this paper. Besides being based on an amorphous oxide semiconductor, the main innovation of this work relies on the use of sputtered multicomponent oxides as dielectric materials based on mixtures of Ta2O5 with SiO2 or Al2O3. These multicomponent dielectrics allow to obtain amorphous structures and low leakage currents while preserving a high dielectric constant. This results in transistors with remarkable electrical properties, such as field-effect mobility exceeding 35 cm2 V-1 s-1, close to 0 V turn-on voltage, on/off ratio higher than 106, and a subthreshold slope of 0.24 V decade-1, obtained with a Ta2O5: SiO2 dielectric. When subjected to severe current stress tests, optimized devices show little and reversible variation in their electrical characteristics. The devices presented here have properties comparable to the ones using plasma-enhanced chemical vapor deposited SiO2 at 400{\textdegree}C, reinforcing the success of this amorphous multicomponent dielectric approach for low temperature, high performance, and transparent electronic circuits. {\textcopyright} 2009 The Electrochemical Society.

}, doi = {10.1149/1.3216049}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-70349755743\&partnerID=40\&md5=e896d6e6d2ee15e0db4e262bf218b391}, author = {Barquinha, P.a , Pereira, L.b , Gon{\c c}alves, G.a , Martins, R.b , Ku{\v s}{\v c}er, D.c , Kosec, M.c , Fortunato, E.a} } @article {Cabrita20021277, title = {Performance of a-Six:C1-x:H Schottky barrier and pin diodes used as position sensitive detectors}, journal = {Journal of Non-Crystalline Solids}, volume = {299}, number = {302}, year = {2002}, note = {

cited By 8

}, pages = {1277-1282}, abstract = {

Position sensitive detectors (PSD) using hydrogenated amorphous silicon as the active layer have been widely proposed either with the p-i-n or the Schottky structure. In this case, the devices are tailored to respond to light in the range 620-650 nm. Little is known about the use of silicon carbide active layers in such devices, which is important when the detected light is in the blue region of the light spectrum. In this paper we present for the first time the electro-optical properties of the a-Six:C1-x:H/Pd and p-ic-n PSD, using a-Six:C1-x:H layers deposited by plasma enhanced chemical vapour deposition (PECVD). These sensors are able to distinguish the wavelength of the impinging visible radiation (from red to blue light). In addition, the sensors respond to light intensities as lower as 1 {\texttimes} 10-6 W cm-2 with a resolution better than 0.04 mm and a linearity between {\textpm}0.12\% and {\textpm}0.8\%. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0022-3093(01)01093-6}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036531797\&partnerID=40\&md5=87ddc9171386a95ab1c40469cd5dadd3}, author = {Cabrita, A., Figueiredo, J., Pereira, L., Silva, V., Brida, D., Fortunato, E., Martins, R.} } @article {Ba{\'\i}a1999171, title = {Performances exhibited by large area ITO layers produced by r.f. magnetron sputtering}, journal = {Thin Solid Films}, volume = {337}, number = {1-2}, year = {1999}, note = {

cited By 56

}, pages = {171-175}, abstract = {

This work refers to the main electro-optical characteristics exhibited by large area indium tin oxide films (300 {\texttimes} 400 mm) produced by r.f. magnetron sputtering under different oxygen concentrations and deposition pressures. Besides that, the ageing effect on the electro-optical characteristics of the films produced was also analyzed. The results achieved show that the film transparency and conductivity were highly improved (more than four orders of magnitude) by first annealing them in air at 470{\textdegree}C, followed by a reannealed stage under vacuum, in a hydrogen atmosphere, at 350{\textdegree}C. The ageing tests show that film degradation occurs when the films are produced at oxygen concentrations above 10\% and/or at deposition pressures above 1.2 {\texttimes} 10-2 mbar. {\textcopyright} 1999 Elsevier Science S.A. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0342487754\&partnerID=40\&md5=bf03261b7c62a1bd637f77ab73956b85}, author = {Ba{\'\i}a, I.a , Quintela, M.b , Mendes, L.a , Nunes, P.a , Martins, R.b} } @article {Martins1999203, title = {Performances of a-Si:H films produced by hot wire plasma assisted technique}, journal = {Vacuum}, volume = {52}, number = {1-2}, year = {1999}, note = {

cited By 3

}, pages = {203-208}, abstract = {

This work reports on the performances of undoped and doped amorphous/nanocrystalline silicon films grown by hot wire plasma assisted technique. The structure (including the presence of several nanoparticles with sizes ranging from 5 nm to 50 nm), composition (oxygen and hydrogen content) and transport properties of the films are highly dependent on the temperature of the filament and on the hydrogen dilution. The undoped films grown under low r.f. power (≈4mWcm-2) and filament temperatures around 1850 K present dark conductivities below 10-10 Scm-1, optical gaps of about 1.6 eV and photosensitivities above 105, (under AM 1.5 light intensities), with almost no traces of oxygen content. For the n- and the p-doped silicon films also fabricated under the same conditions the conductivities obtained are of about 10-2Scm-1 and 10-5Scm-1, respectively. {\textcopyright} 1998 Elsevier Science Ltd. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032762765\&partnerID=40\&md5=8a6a611722aa5d787afd005b7c9df986}, author = {Martins, R., Ferreira, I., Fernandas, B., Fortunato, E.} } @article {Martins2006238, title = {Performances of an in-line PECVD system used to produce amorphous and nanocrystalline silicon solar cells}, journal = {Thin Solid Films}, volume = {511-512}, year = {2006}, note = {

cited By 0

}, pages = {238-242}, abstract = {

This paper presents the performances of an in-line plasma enhanced chemical vapor deposition system constituted by 5 chambers and one external unloaded chamber used in the simultaneous manufacturing of 4 large (30 cm {\texttimes} 40 cm) solar cells deposited on glass substrates. The system is fully automatically controlled by a Programmable Logic Controller using a specific developed software that allows devices mass production without losing the flexibility to perform process innovations according to the industrial requests, i.e. fast and secure changes and optimizations. Overall, the process shift is of about 15 min per each set of 4 solar cells. Without a buffer layer, solar cells with efficiencies of about 9\% were produced by the proper tuning of the i-layer production conditions. {\textcopyright} 2005 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2005.12.001}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33646818669\&partnerID=40\&md5=377180ac16ad2c296966d648df71be4d}, author = {Martins, N.a , Canhola, P.a , Quintela, M.b , Ferreira, I.c , Raniero, L.c , Fortunato, E.c , Martins, R.b c c} } @article {Fortunato2000765, title = {Performances of an optical ruler based on one-dimensional hydrogenated amorphous Si position-sensitive detectors produced using different metal contacts}, journal = {Philosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties}, volume = {80}, number = {4}, year = {2000}, note = {

cited By 5

}, pages = {765-774}, abstract = {

The aim of this work is to determine the role of different metal contacts on the performances of one-dimensional thin-film position-sensitive detectors produced by plasma-enhanced chemical vapour deposition, to be used in optical rulers for alignment applications. The device consists on an indium tin oxide/p-i-n structure where the metal contacts used were based on Al, Al + Cu and Ag. The results achieved show that the contact mainly influences the final sensor range by limiting the magnitude of the analogue signals recorded. In spite of soldering problems the Al contact was the contact that lead to better discrimination of the sensor, with a nonlinearity of {\textpm}0.8\% and a fall-off parameter of 3.2 {\texttimes} 10-3 cm-1. The Al + Cu contact also exhibits good performances (nonlinearity, of {\textpm}1.1\%; fall-off parameter, 1.4 {\texttimes} 10-2 cm-1) and should be chosen since it is much easier to solder but requires protection against oxidation. The integration of these sensors on the optical ruler lead to the production of a system with a response time below 0.5 ms, an accuracy better than {\textpm}1\% and a mechanical precision of better than 0.25 mm in 100 mm, with a full-scale noise below {\textpm}0.1\%.

}, doi = {10.1080/014186300255393}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-18744388272\&partnerID=40\&md5=22ac83381f345d1e68a7446adfcf675b}, author = {Fortunato, E.a , Teodoro, P.a , Silva, V.a , Ferreira, I.a , Nunes, Y.a , Guimar{\~a}es, N.a , Soares, F.a , Giuliani, F.a , Popovic} } @article {Pereira200489, title = {Performances of hafnium oxide produced by radio frequency sputtering for gate dielectric application}, journal = {Materials Science and Engineering B: Solid-State Materials for Advanced Technology}, volume = {109}, number = {1-3}, year = {2004}, note = {

cited By 34

}, pages = {89-93}, abstract = {

The search for new dielectric materials to be used in metal-insulator- semiconductor (MIS) structures to replace the silicon oxide (SiO2) has been growing up. The aim is to have materials with high dielectric constants that could allow the use of thicker films and so, to reduce the role of leakage currents that happens in devices using very thin SiO2 layers or to allow the MIS devices to support high currents, besides having a retain memory effect. In this work, we present data concerning the production of hafnium oxide (HfO2) thin films by radio frequency (rf) sputtering that present suitable characteristics to be used as a gate dielectric, taking advantage of its high dielectric constant and stoichiometry reached under certain deposition conditions. Data concerning the role of the deposition parameters in the films structure and in the electrical properties of the films produced using capacitance-voltage (C-V) and current-voltage (I-V) measurements will be shown, together with data concerning the degree of films{\textquoteright} compactness measured by spectroscopic ellipsometry (SE). {\textcopyright} 2003 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.mseb.2003.10.053}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-2342450573\&partnerID=40\&md5=3578ae027a7f3ac69190c5d574d2b56e}, author = {Pereira, L., Marques, A., {\'A}guas, H., Nedev, N., Georgiev, S., Fortunato, E., Martins, R.} } @article {Parthiban2013825, title = {Performances of microcrystalline zinc tin oxide thin-film transistors processed by spray pyrolysis}, journal = {IEEE/OSA Journal of Display Technology}, volume = {9}, number = {10}, year = {2013}, note = {

cited By 4

}, pages = {825-831}, abstract = {

In this work, we report results concerning the performances of thin-film transistors (TFTs) where the channel layer is based on microcrystalline zinc tin oxide (ZTO) processed by spray pyrolysis technique. TFTs made with 30 nm thick ZTO channel layer deposited at a substrate temperature of 400 C and 300 Cexhibited, respectively, a saturation mobility of 2.9 cm V s and 1.45 cm V s ; voltage of 0.15 V, and 0.2 V; a sub-threshold swing of 400 mV/dec and 500 mV/dec; ON/OFF ratio at the onset of hard saturation current of 3.5 10 and 6 10 , for a drain to source voltage of 10 V (close to or below the gate to source voltage). This indicates that the substrate temperature is relevant in determining the devices{\textquoteright} electronic performances. {\textcopyright} 2013 IEEE.

}, doi = {10.1109/JDT.2013.2262096}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84887091262\&partnerID=40\&md5=2d0cf558bd7e2e0d82bc434b51e87dc1}, author = {Parthiban, S., Elangovan, E., Nayak, P.K., Gon{\c c}alves, A., Nunes, D., Pereira, L., Barquinha, P., Busani, T., Fortunato, E., Mart} } @article {Fortunato1996148, title = {Performances presented by large-area thin film position-sensitive detectors based on amorphous silicon}, journal = {Thin Solid Films}, volume = {272}, number = {1}, year = {1996}, note = {

cited By 2

}, pages = {148-156}, abstract = {

This paper presents a low-cost technology for the realisation of large-area thin film position-sensitive detectors using the a-Si:H technology. The obtained results are quite promising regarding the application of these sensors to a wide variety of optical inspection systems, such as: machine tool alignment and control; angle measuring; rotation monitoring; surface profiling; medical instrumentation; targeting; remote optical alignment; guidance systems; etc., to which automated inspection control is needed.

}, doi = {10.1016/0040-6090(95)06976-3}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029772806\&partnerID=40\&md5=841078712d398275d6d718ce89dd1c01}, author = {Fortunato, E., Lavareda, G., Scares, F., Martins, R.} } @article {Nunes2002293, title = {Performances presented by zinc oxide thin films deposited by r.f. magnetron sputtering}, journal = {Vacuum}, volume = {64}, number = {3-4}, year = {2002}, note = {

cited By 98

}, pages = {293-297}, abstract = {

In this work, we report the electro-optical properties exhibited by ZnO:A1 thin films deposited by r.f. magnetron sputtering. The effect of the deposition parameters on the properties of the films were studied with the aim to determine the most suitable deposition conditions to obtain ZnO:Al thin films with a low resistivity and high transmittance, characteristics required for applications on optoelectronic devices. After annealing, the ZnO:Al thin films present a low resistivity (6.25 {\texttimes} 10-3 Ωcm) and a high transmittance (90\%) when produced with a deposition pressure of 1.6 {\texttimes} 10-2 mbar and r.f. power of 150W. {\textcopyright} 2002 Elsevier Science Ltd. All rights reserved.

}, doi = {10.1016/S0042-207X(01)00323-2}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036135380\&partnerID=40\&md5=96f0e4d899c37003fe3d71a9ef05126f}, author = {Nunes, P., Costa, D., Fortunato, E., Martins, R.} } @article {Nunes1999176, title = {Performances presented by zinc oxide thin films deposited by spray pyrolysis}, journal = {Thin Solid Films}, volume = {337}, number = {1-2}, year = {1999}, note = {

cited By 144

}, pages = {176-179}, abstract = {

The effect of doping and annealing atmosphere on the performances of zinc oxide thin films prepared by spray pyrolysis have been studied. The results show that the way doping influences the electrical and structural properties depends also on the characteristics of the doping element. Annealing the as-deposited films in an inert atmosphere leads to a substantial reduction in the resistivity of the films deposited and to an increase on the degree of film{\textquoteright}s crystallinity. {\textcopyright} 1999 Elsevier Science S.A. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000475707\&partnerID=40\&md5=f4ee5924c994256c7e7e8576caf0e216}, author = {Nunes, P.a , Fernandes, B.a , Fortunato, E.a , Vilarinho, P.b , Martins, R.a} } @article {Nunes2016262, title = {Photocatalytic behavior of TiO2 films synthesized by microwave irradiation}, journal = {Catalysis Today}, volume = {278}, year = {2016}, note = {

cited By 0

}, pages = {262-270}, abstract = {

Titanium dioxide was synthesized on glass substrates from titanium (IV)isopropoxide and hydrochloride acid aqueous solutions through microwave irradiation using as seed layer either fluorine-doped crystalline tin oxide (SnO2:F) or amorphous tin oxide (a-SnOx). Three routes have been followed with distinct outcome: (i) equimolar hydrochloride acid/water proportions (1HCl:1water) resulted in nanorod arrays for both seed layers; (ii) higher water proportion (1HCl:3water) originated denser films with growth yield dependent on the seed layer employed; while (iii) higher acid proportion (3HCl:1water) hindered the formation of TiO2. X-ray diffraction (XRD) showed that the materials crystallized with the rutile structure, possibly with minute fractions of brookite and/or anatase. XRD peak inversions observed for the materials synthesized on crystalline seeds pointed to preferred crystallographic orientation. Electron diffraction showed that the especially strong XRD peak inversions observed for TiO2 grown from the 1HCl:3water solution on SnO2:F originated from a [001] fiber texture. Transmittance spectrophotometry showed that the materials with finer structure exhibited significantly higher optical band gaps. Photocatalytic activity was assessed from methylene blue degradation, with the 1HCl:3water SnO2:F material showing remarkable degradability performance, attributed to a higher exposure of (001) facets, together with stability and reusability. {\textcopyright} 2015 Elsevier B.V.

}, doi = {10.1016/j.cattod.2015.10.038}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994054745\&partnerID=40\&md5=43f87b5c8042319b7c90385efcb94072}, author = {Nunes, D.a , Pimentel, A.a , Pinto, J.V.a , Calmeiro, T.R.a , Nandy, S.a , Barquinha, P.a , Pereira, L.a , Carvalho, P.A.b c , F} } @article {Fortunato1998202, title = {Photochemical sensors based on amorphous silicon thin films}, journal = {Sensors and Actuators, B: Chemical}, volume = {B46}, number = {3}, year = {1998}, note = {

cited By 4

}, pages = {202-207}, abstract = {

Hydrogenated amorphous silicon photochemical sensors based on Pd metal/insulator/semiconductor (Pd-MIS) structures were produced by plasma enhanced chemical vapour deposition (PECVD) with two different oxidized surfaces (thermal and chemical oxidation). The behaviour of dark and illuminated current-voltage characteristics in air and in the presence of a hydrogen atmosphere is explained by the changes induced by the gases adsorbed, in the work function of the metal, modifying the electrical properties of the interface. The photochemical sensors produced present more than two orders of magnitude variation on the reverse dark current in the presence of 400 ppm hydrogen. When the sensors are submitted to light it corresponds a decrease of 45\% on the open circuit voltage.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032021479\&partnerID=40\&md5=c819f4dbd5083a67993af86752bafe49}, author = {Fortunato, Elvira, Malik, Alexander, Martins, Rodrigo} } @article {Martins20092121, title = {Physica Status Solidi (A) Applications and Materials: Preface}, journal = {Physica Status Solidi (A) Applications and Materials Science}, volume = {206}, number = {9}, year = {2009}, note = {

cited By 0

}, pages = {2121}, abstract = {n/a}, doi = {10.1002/pssa.200881800}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-70349100036\&partnerID=40\&md5=2992aed060ee15b64bc23ba04d49081a}, author = {Martins, R.} } @article {Cui20047, title = {Physical properties of sputtered ITO and WO3 thin films}, journal = {Materials Science Forum}, volume = {455-456}, year = {2004}, note = {

cited By 3

}, pages = {7-11}, abstract = {

Electrochromic coatings are used in a wide range of technical fields. This paper refers to the properties of amorphous Indium-tin-oxide (ITO) and WO 3 thin films obtained by dc-magnetron reactive sputtering in different oxygen partial pressures (PO2) at room temperature (RT). SEM, XRD and UV-Vis-NIR spectroscopy characterized the films prepared in terms of morphology, structure, and optical and electrical properties. The maximum of the optical transmittance in the visible range for the ITO and WO3 films was above 97\% and 98\%, respectively. These films were incorporated into ECDs (electrochromic devices) whose performance was assessed by optical methods.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17144451866\&partnerID=40\&md5=5e2aaee9b9e825a1caa2cae027d17442}, author = {Cui, H.-N.a , Teixeira, V.a , Monteiro, A.a d , Fortunato, E.b , Martins, R.b , Bertran, E.c} } @article {{\'A}guas200031, title = {Plasma diagnostics of a PECVD system using different R.F. electrode configurations}, journal = {Vacuum}, volume = {56}, number = {1}, year = {2000}, note = {

cited By 9

}, pages = {31-37}, abstract = {

This work aims to study the role of the r.f. electrode configuration on the plasma characteristics of a PECVD asymmetric reactor. The configurations used are the usual diode configuration, the triode configuration and a new configuration that we named short-circuited grid electrode (SGE). The plasma generated was characterized with the use of a Langmuir probe and an impedance probe. We demonstrate that the plasma parameters are highly dependent on the reactor geometry. The results achieved show that by changing the r.f. electrode configuration the DC self-bias varies from about 100 to close to 0 V. This variation causes changes in the ion bombardment of the reactor surfaces, which can affect the growing of the films deposited. We also demonstrate that for the SGE configuration the area seen by the plasma does not correspond to the exposed physical area of the electrode, and we suggest a model to explain this phenomenon.

}, doi = {10.1016/S0042-207X(99)00157-8}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033908301\&partnerID=40\&md5=476b02ee940cab988396c1ec2582800e}, author = {{\'A}guas, H., Martins, R., Fortunato, E.} } @article {Branquinho2013723, title = {Plastic compatible sputtered ta-inf o sensitive layer for oxide semiconductor tft sensors}, journal = {IEEE/OSA Journal of Display Technology}, volume = {9}, number = {9}, year = {2013}, note = {

cited By 3

}, pages = {723-728}, abstract = {

The effect of post-deposition annealing temperature on the pH sensitivity of room temperature RF sputtered +{\hbox{Ta}}-{2}{\hbox{O}}5 was investigated. Structural and morphological features of these films were analyzed before and after annealing at various temperatures. The deposited films are amorphous up to 600 +^{\circ}{\hbox{C}}+ and crystallize at 700 +^{\circ}{\hbox{C}}+ in an orthorhombic phase. Electrolyte-insulator- semiconductor (EIS) field effect based sensors with an amorphous +{\hbox{Ta}}-{2}{\hbox{O}}5 sensing layer showed pH sensitivity above 50 mV/pH. For sensors annealed above 200 +^{\circ}{\hbox{C}}+ pH sensitivity decreased with increasing temperature. Stabilized sensor response and maximum pH sensitivity was achieved after low temperature annealing at 200 +^{\circ}{\hbox{C}}+ , which is compatible with the use of polymeric substrates and application as sensitive layer in oxides TFT-based sensors. {\textcopyright} 2005-2012 IEEE.

}, doi = {10.1109/JDT.2012.2229693}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84883805532\&partnerID=40\&md5=27694e4b07d737319719fccf41d74ce4}, author = {Branquinho, R., Pinto, J.V., Busani, T., Barquinha, P., Pereira, L., Baptista, P.V., Martins, R., Fortunato, E.} } @article {Pereira200628, title = {Poly-Si thin film transistors: Effect of metal thickness on silicon crystallization}, journal = {Materials Science Forum}, volume = {514-516}, number = {PART 1}, year = {2006}, note = {

cited By 0

}, pages = {28-32}, abstract = {

In this work metal induced crystallization (MIC) using nickel (Ni) was employed to obtain poly-Si by crystallization of amorphous films for application as active layer in TFTs. Ni layers with thicknesses of 0.5 nm, 1 nm and 2 nm were used to crystallize the silicon. The TFTs were produced with a bottom gate configuration using a multi-layer Al2O3/TiO2 insulator produced by atomic layer deposition (ALD) as gate dielectric. The best performances of the TFT produced were obtained when using very thin Ni layers for the crystallization. This is attributed to a lower metal contamination and to the enhancement of grain size, as a result of the lower nucleation density achieved, when using the thinnest Ni layer. Devices that exhibit effective mobility of 45.5 cm2V-1s-1 and an on/off ratio of 5.55{\texttimes}104 were produced using a 0.5 nm Ni layer to crystallize the active channel area.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-37849047690\&partnerID=40\&md5=c13156454d87f2f3fb32a5e19ea26118}, author = {Pereira, L., Barquinha, P., Fortunato, E., Martins, R.} } @article {Pimentel2005212, title = {Polycrystalline intrinsic zinc oxide to be used in transparent electronic devices}, journal = {Thin Solid Films}, volume = {487}, number = {1-2}, year = {2005}, note = {

cited By 32

}, pages = {212-215}, abstract = {

In this paper we present results of intrinsic/non-doped zinc oxide deposited at room temperature by radio frequency magnetron sputtering able to be used as a semiconductor material on electronic devices, like for example ozone gas sensors, ultra-violet detectors and thin film transistors. These films present a resistivity as high as 2.5{\texttimes}108 Ω cm with an optical transmittance of 90\%. Concerning the structural properties, these films are polycrystalline presenting a uniform and very smooth surface. {\textcopyright} 2005 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2005.01.067}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-22944488292\&partnerID=40\&md5=34e25c8b4384c98e8a29038e4ac3d405}, author = {Pimentel, A., Fortunato, E., Gon{\c c}alves, A., Marques, A., {\'A}guas, H., Pereira, L., Ferreira, I., Martins, R.} } @article {Pereira2004178, title = {Polycrystalline silicon obtained by gold metal induced crystallization}, journal = {Journal of Non-Crystalline Solids}, volume = {338-340}, number = {1 SPEC. ISS.}, year = {2004}, note = {

cited By 19

}, pages = {178-182}, abstract = {

The aim of this paper is to study the role of gold (Au) induced crystallization on amorphous silicon (a-Si) films produced by low pressure chemical vapor deposition (LPCVD) at low process temperatures (550 {\textdegree}C) to allow the use of glass substrates. Concerning the crystallization process Au was deposited by e-beam thermal evaporation over the silicon (Si), using different metal thickness, from 5 to 100 {\r A}. The samples were then annealed at 450, 500 and 550 {\textdegree}C and the crystallization time was changed from 5 up to 30 h. The structure of the films was analyzed by X-ray diffraction (XRD) and spectroscopic ellipsometry (SE) while electrical conductivity measurements were performed to obtain the electrical properties of the films produced, namely the activation energy (EA) and how it changes with the Au thickness used. The data achieved show that the increase of the metal layer thickness decreases the time needed to get full crystallization. However this leads to lower conduction activation energy (EA) meaning that there is also an increase of Au incorporation that leads to the production of doped films. {\textcopyright} 2004 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2004.02.048}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-2942527310\&partnerID=40\&md5=148ca8de4b12ef5100077374683ec2a5}, author = {Pereira, L., {\'A}guas, H., Martins, R.M., Fortunato, E., Martins, R.} } @article {Pereira2004334, title = {Polycrystalline silicon obtained by metal induced crystallization using different metals}, journal = {Thin Solid Films}, volume = {451-452}, year = {2004}, note = {

cited By 31

}, pages = {334-339}, abstract = {

The aim of this paper is to study the role of different metals (aluminium, molybdenum, nickel and titanium) in inducing crystallization in films produced by LPCVD at high and low temperature processes and to compare the structural, morphological, optical and electrical properties of the various films produced. This work envisages the use of the most suitable conditions that lead to the production of films for optoelectronic applications such as solar cells. {\textcopyright} 2003 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2003.10.124}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17644449058\&partnerID=40\&md5=5b3211498107a42d6e97dec663fe0fd4}, author = {Pereira, L.a , {\'A}guas, H.a , Martins, R.M.S.a , Vilarinho, P.b , Fortunato, E.a , Martins, R.a} } @article {Bernardo20091112, title = {Polymer light-emitting diodes with amorphous indium-zinc oxide anodes deposited at room temperature}, journal = {Synthetic Metals}, volume = {159}, number = {11}, year = {2009}, note = {

cited By 12

}, pages = {1112-1115}, abstract = {

The authors report on the performance of polymer-based light-emitting diodes, LEDs, using amorphous zinc oxide-doped indium oxide, IZO, as anode. In particular, LEDs with poly[(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] as electroluminescent layer and aluminium cathodes, show higher efficiency with this IZO anode (0.015 cd/A) than with indium-tin oxide (ITO) (0.010 cd/A). Inspite of the higher resistance of this IZO electrode, compared with ITO, the fact that it can be processed at lower temperatures and allows similar or even higher efficiency values for polymer LEDs make this material a good candidate for display and other optoelectronic applications. {\textcopyright} 2009 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.synthmet.2009.01.037}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67349115685\&partnerID=40\&md5=e6d0f03a8e715985ba2a59ace464cb43}, author = {Bernardo, G.a , Gon{\c c}alves, G.b , Barquinha, P.b , Ferreira, Q.a , Brotas, G.a , Pereira, L.b , Charas, A.a , Morgado, J.a c , Ma} } @article {{\'A}guas20036, title = {Polymorphous silicon deposited in large area reactor at 13 and 27 MHz}, journal = {Thin Solid Films}, volume = {427}, number = {1-2}, year = {2003}, note = {

cited By 7

}, pages = {6-10}, abstract = {

Despite of a growing interest in this material, until now the studies on polymorphous silicon (pm-Si:H) have been performed on small laboratory reactors working at 13.56 MHz. Envisaging an industrial application of pm-Si:H, the technology was transferred to a large area plasma enhanced chemical vapour deposition reactor (25 {\texttimes} 40 cm2) working at excitation frequencies of 13.56 and 27.12 MHz. The plasma was characterized by impedance probe measurements and the films were characterized by spectroscopic ellipsometry, infrared spectroscopy and hydrogen evolution experiments, which are techniques that allow a rapid and reliable identification of pm-Si:H structure. Conductivity measurements were also performed to determine their transport properties. The results show that scaling up using the 13.56 MHz was successfully done and pm-Si:H films were deposited at a growth rate of ≈ 12 nm/min. Moreover, by using the 27.12 MHz excitation frequency the growth rate was even further increased to above 18 nm/min, as desired for industrial production. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0040-6090(02)01172-0}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037416699\&partnerID=40\&md5=cdae65de09de26f0bc9e1435f8cf7e30}, author = {{\'A}guas, H.a , Roca i Cabarrocas, P.b , Lebib, S.b , Silva, V.a , Fortunato, E.a , Martins, R.a} } @article {Martins2003333, title = {Polymorphous Silicon Films Deposited at 27.12 MHz}, journal = {Advanced Materials}, volume = {15}, number = {24}, year = {2003}, note = {

cited By 1

}, pages = {333-337}, abstract = {

This paper describes, for the first time, a method of producing polymorphous silicon (pm-Si:H) films by plasma-enhanced (PE) CVD, using an excitation frequency of 27.12 MHz. The aim is to produce, at high growth rates, nanostructured films that are more stable than the conventional amorphous or polymorphous silicon films grown by PECVD at 13.56 MHz. The processing data show that, at 27.12 MHz, the pm-Si:H films are produced close to the transition region from amorphous to microcrystalline silicon films, at a growth rate of about 0.3 nm s-1, using pressures above 160 Pa. Apart from that, the analysis of the exodiffusion, spectroscopic ellipsometry (SE), and micro Raman data reveal that these films are more dense and compact than the polymorphous films grown at 13.56 MHz.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0346640559\&partnerID=40\&md5=1f2c136ab6644bc22947a13cb0ad7026}, author = {Martins, R.a , {\'A}guas, H.a , Ferreira, I.a , Fortunato, E.a , Lebib, S.b , Roca i Cabarrocas, P.b , Guimar{\~a}es, L.a} } @article {Martins2003333, title = {Polymorphous silicon films deposited at 27.12 MHz}, journal = {Chemical Vapor Deposition}, volume = {9}, number = {6}, year = {2003}, note = {

cited By 12

}, pages = {333-337}, abstract = {

This paper describes, for the first time, a method of producing polymorphous silicon (pm-Si:H) films by plasma-enhanced (PE) CVD, using an excitation frequency of 27.12 MHz. The aim is to produce, at high growth rates, nanostructured films that are more stable than the conventional amorphous or polymorphous silicon films grown by PECVD at 13.56 MHz. The processing data show that, at 27.12 MHz, the pm-Si:H films are produced close to the transition region from amorphous to microcrystalline silicon films, at a growth rate of about 0.3 nms-1, using pressures above 160 Pa. Apart from that, the analysis of the exodiffusion, spectroscopic ellipsometry (SE), and micro Raman data reveal that these films are more dense and compact than the polymorphous films grown at 13.56 MHz.

}, doi = {10.1002/cvde.200306261}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-10644291047\&partnerID=40\&md5=7fc8fe13f57cea6b3fda8a7f5ed2174c}, author = {Martins, R.a , {\'A}guas, H.a , Ferreira, I.a , Fortunato, E.a , Lebib, S.b , I Cabarrocas, P.R.b , Guimar{\~a}es, L.a} } @article {Ferreira2004344, title = {Porous a/nc-Si:H films produced by HW-CVD as ethanol vapour detector and primary fuel cell}, journal = {Sensors and Actuators, B: Chemical}, volume = {103}, number = {1-2}, year = {2004}, note = {

cited By 14

}, pages = {344-349}, abstract = {

This work reports the use of undoped porous amorphous/nanocrystalline hydrogenated silicon (a/nc-Si:H) thin films produced by hot wire chemical vapour deposition (HW-CVD) as ethanol detector above 50ppm and as a primary fuel cell where a power of 4μW/cm2 was obtained in structures of the type glass/ITO/i-a-nc-Si:H/Al. The porous silicon looks like a sponge constituted by grains and cluster of grains that determines the type of surface morphology and the behaviour of the structure under the presence of vapour moisture. Apart from that, the detector/device performances will also depend on the type of interlayer and interfaces with the metal contacts. The sponge like structure adsorbs the OH groups in uncompensated bonds, which behave as donor-like carriers, leading to an increase in the current flowing through the material, directly dependent on the ethanol vapour pressure. The corresponding role of the components of the microstructure on this detector was investigated by spectroscopic impedance. The response time of the current of the sensor and its recovery time are in the range of 10-50s at room temperature. {\textcopyright} 2004 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.snb.2004.04.064}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-4444347784\&partnerID=40\&md5=04d9e87cbd0ce6106d2375d87bb6313d}, author = {Ferreira, I., Igreja, R., Fortunato, E., Martins, R.} } @article {Silva20112012, title = {Portable optoelectronic biosensing platform for identification of mycobacteria from the Mycobacterium tuberculosis complex}, journal = {Biosensors and Bioelectronics}, volume = {26}, number = {5}, year = {2011}, note = {

cited By 17

}, pages = {2012-2017}, abstract = {

In this paper we report on the fabrication and performance of a portable and low cost optoelectronic platform integrating a double color tuned light emitting diode as light source, an amorphous/nanocrystalline silicon photodetector with a flat spectral response in the wavelength range from 520. nm to 630. nm and integrated electronic for signal acquisition and conditioning constituted by current to voltage converter, a filter and an amplification stage, followed by an analog to digital converter, with appropriate software for full automation to minimize human error. Incorporation of the double color tuned light emitting diode provides for a simple yet innovative solution to signal acquisition independently from the light intensity and/or solution concentration, while considerably decreasing production costs. Detection based on Au-nanoprobes constitutes the biorecognition step and allowed identification of specific sequences of Mycobacterium tuberculosis complex, namely Mycobacterium bovis and M. tuberculosis in biological samples. {\textcopyright} 2010 Elsevier B.V.

}, doi = {10.1016/j.bios.2010.08.078}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-78650610360\&partnerID=40\&md5=3882549c44806ac6d2fc62b29a41f7e2}, author = {Silva, L.B.a , Veigas, B.b , Doria, G.b , Costa, P.c , In{\'a}cio, J.c , Martins, R.a , Fortunato, E.a , Baptista, P.V.b} } @article {Martins2006, title = {Preface}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 1

}, pages = {vii}, abstract = {n/a}, doi = {10.1016/j.jnoncrysol.2006.03.007}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33744532487\&partnerID=40\&md5=11ad8f7706714e7e798eaf4d515b4b35}, author = {Martins, R., Chu, V., Fortunato, E., Conde, J.P., Ferreira, I.} } @article {Elangovan20075512, title = {Preliminary studies on molybdenum-doped indium oxide thin films deposited by radio-frequency magnetron sputtering at room temperature}, journal = {Thin Solid Films}, volume = {515}, number = {13}, year = {2007}, note = {

cited By 10

}, pages = {5512-5518}, abstract = {

Thin films of molybdenum-doped indium oxide (IMO) were prepared by a 3-source, cylindrical radio-frequency magnetron sputtering at room temperature. The films were post-annealed and were characterized by their structural (X-ray diffraction) and optical (UV-VIS-NIR spectrophotometer) properties. The films were studied as a function of oxygen volume percentage (O2 vol.\%) ranging from 3.5 to 17.5. The structural studies revealed that the as-deposited amorphous films become crystalline on annealing. In most cases, the (222) reflection emerged as high intensive peak. The poor visible transmittance of the films as-deposited without oxygen was increased from \~{} 12\% to over 80\% on introducing oxygen (3.5 O2 vol.\%). For the films annealed in open air, the average visible transmittance in the wavelength ranging 400-800~nm was varied between 77 and 84\%. The films annealed at high temperatures (\> 300~{\textdegree}C) decreased the transmittance to as low as \< 1\%. The optical band gap of the as-deposited films increased from the range 3.83-3.90 to 3.85-3.98~eV on annealing at different conditions. {\textcopyright} 2007 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2007.01.022}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34047112710\&partnerID=40\&md5=1d7e1f91af44a815558192d307bc8dda}, author = {Elangovan, E., Marques, A., Fernandes, F.M.B., Martins, R., Fortunato, E.} } @article {Ramos201326, title = {Preparation and characterization of cellulose nanocomposite hydrogels as functional electrolytes}, journal = {Solid State Ionics}, volume = {242}, year = {2013}, note = {

cited By 4

}, pages = {26-32}, abstract = {

In this work Laponite was combined with a modified abundant natural polymer, (caboxymethyl cellulose), acrylic sodium salt polymer and lithium perchlorate aiming to produce inexpensive and sustainable nanocomposite electrolytes for functional electrochemical devices. Optical, electrochemical, structural, morphological and rheological characterization was performed in order to evaluate their properties and potential advantages as electrolyte. It was verified that the addition of Laponite led to an ionic conductivity at room temperature (25 C) in the range of 6 to 9 {\texttimes} 10- 5 Scm - 1 this value being then determined by the composition of the nanocomposite. These electrolytes were applied to electrochromic devices using evaporated nickel oxide thin film as the electrochromic layer. The devices exhibited a significant transmittance modulation that exceeds 45 \% at 600 nm. {\textcopyright} 2013 Elsevier B.V.

}, doi = {10.1016/j.ssi.2013.03.028}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84877757446\&partnerID=40\&md5=b339279a2aadf2aeff0426acb49a5f90}, author = {Ramos, A.M.a b , Pereira, S.a b , Cidade, M.T.a , Pereira, G.a , Branquinho, R.a , Pereira, L.a b , Martins, R.a b , Fortunato,} } @article {Fortunato2001310, title = {Production and characterization of large area flexible thin film position sensitive detectors}, journal = {Thin Solid Films}, volume = {383}, number = {1-2}, year = {2001}, note = {

cited By 11

}, pages = {310-313}, abstract = {

Flexible large area thin film position sensitive detectors based on amorphous silicon technology were prepared on polyimide substrates using the conventional plasma enhanced chemical vapor deposition technique. The sensors were characterized by spectral response, illuminated I-V characteristics position detectability measurements and atomic force microscopy. The obtained one-dimensional position sensors, 5-mm wide and 60-mm long, presented a maximum spectral response at 600 nm, an open circuit voltage of 0.6 V and a position detectability with a correlation of 0.9989 associated to a S.D. of 1{\texttimes}10-2, comparable to those produced on glass substrates.

}, doi = {10.1016/S0040-6090(00)01610-2}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035247756\&partnerID=40\&md5=9bb98b5b123939db543e50223e42f148}, author = {Fortunato, E., Brida, D., Ferreira, I., {\'A}guas, H., Nunes, P., Martins, R.} } @article {Bender200245, title = {Production and characterization of zinc oxide thin films for room temperature ozone sensing}, journal = {Thin Solid Films}, volume = {418}, number = {1}, year = {2002}, note = {

cited By 73

}, pages = {45-50}, abstract = {

The room temperature ozone sensing properties of polycrystalline undoped zinc oxide (ZnO) thin films have been investigated. ZnO thin films have been produced by the d.c. and r.f. magnetron sputtering technique as well as with spray pyrolysis with a variety of parameters. The as-grown films were brought to a high conducting state through a reversible photoreduction process by UV light exposure and were subsequently exposed to ozone resulting in a strong resistivity increase caused by re-oxidation. The magnitude of the effect was largest for the sputtered films, which exhibited resistivity changes of more than 8 orders of magnitude, whereas films deposited by spray pyrolysis showed changes of less than 3 orders of magnitude. XRD and AFM analysis of the films revealed that all films were microcrystalline. The film texture, however, was strongly related to the growth technique and the parameters used. Best results were achieved with r.f.-sputtered films, which have been deposited at high total pressures. These films exhibited a sensor response of 1.2 {\texttimes} 108. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0040-6090(02)00588-6}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036798291\&partnerID=40\&md5=a5bd3d833a263f1396b079cebc333a14}, author = {Bender, M.a , Gagaoudakis, E.a , Douloufakis, E.a , Natsakou, E.a , Katsarakis, N.a , Cimalla, V.a , Kiriakidis, G.a , Fortunato} } @article {Ferreira2000292, title = {Production of low cost contacts and joins for large area devices by electrodeposition of Cu and Sn}, journal = {Applied Surface Science}, volume = {168}, number = {1-4}, year = {2000}, note = {

cited By 4

}, pages = {292-295}, abstract = {

The aim of this paper is to present results concerning the morphology, structure, mechanical and electrical characteristics of the new proposed Cu-Sn metallurgical alloy, which may be used in electronic joins. By proper choice of process temperature and pressure, Cu coated surfaces are soldered using Sn as pre-form. The main results achieved indicate that the formation of Cu3Sn phase begins at a temperature of about 473 K and that the Sn thickness (dSn) needed is slightly above 7 μm. Due to join wettability, higher temperatures (between 523 and 573 K) and dSn above 35 μm are required to form joins within the specifications of the electronic industry.

}, doi = {10.1016/S0169-4332(00)00627-9}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034514366\&partnerID=40\&md5=81b7868752c4045e10af1911614e4714}, author = {Ferreira, J.a , Seiroco, H.a , Braz Fernandes, F.a , Martins, R.a , Fortunato, E.a , Marv{\~a}o, A.P.b , Martins, J.I.c} } @article {Ferreira200230, title = {The properties of a-Si:H films deposited on Mylar substrates by hot-wire plasma assisted technique}, journal = {Journal of Non-Crystalline Solids}, volume = {299-302}, year = {2002}, note = {

cited By 0

}, pages = {30-35}, abstract = {

In this work we studied the influence of hydrogen dilution, rf power, and the filament and substrate temperatures on the electro-optical properties and composition of a-Si:H films produced by hot wire plasma assisted technique. The a-Si:H films were produced on Mylar substrates with growth rate of up to 37 {\r A}/s, ημτ product of 1.6 {\texttimes} 10-7 cm2/V, photoconductivity to dark conductivity ratio of 1 {\texttimes} 104 (at AM1.5 radiation), and a dark conductivity of about 10-10 (Ω cm)-1 for substrate temperature of 130 {\textdegree}C, hydrogen dilution of 99\%, filament temperature of 1700 {\textdegree}C, and rf power of 100 W. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0022-3093(01)01173-5}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036539809\&partnerID=40\&md5=d0767068690d5cab263243218012216d}, author = {Ferreira, I.a , Fortunato, E.a , Pereira, L.a , Costa, M.E.V.b , Martins, R.a} } @article {Ferreira2004366, title = {Properties of a-Si:H intrinsic films produced by HWPA-CVD technique}, journal = {Thin Solid Films}, volume = {451-452}, year = {2004}, note = {

cited By 0

}, pages = {366-369}, abstract = {

In this paper, we investigate the optoelectronic properties and the photodegradation of amorphous silicon films produced by the hot wire plasma assisted technique (HWPA-CVD). We observed that hydrogen dilution in the gas phase plays an important role in the time dependence of the photoconductivity, which is correlated with an enhancement of defect density. We also compare the degradation of these films with those produced by plasma enhanced and by hot wire chemical vapour deposition techniques (PECVD and HW-CVD) and we found lower time dependence for the photodegradation of the films produced by HWPA-CVD technique {\textcopyright} 2003 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2003.10.145}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17644445889\&partnerID=40\&md5=9092d994ea27136dcdceb7ecf0e8fd62}, author = {Ferreira, I., {\'A}guas, H., Pereira, L., Fortunato, E., Martins, R.} } @article {Wang20111490, title = {Properties of P-doped ZnO films RF-sputtered at different substrate temperature}, journal = {Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering}, volume = {40}, number = {8}, year = {2011}, note = {

cited By 3

}, pages = {1490-1494}, abstract = {

In order to study the properties of P-doped ZnO films deposited at low temperature substrates, P-doped ZnO films were RF-sputtered on sapphire substrates in the range from RT to 350{\textdegree}C. XRD spectra indicated the growth of the crystallites along the strongest \<001\> orientation. Further ZnO (002) peak became the weakest when the film was sputtered at 250{\textdegree}C. AFM pictures showed that the surface morphology varied with the deposition temperature. The sample RMS increased with the increase of substrate temperature. XPS spectra showed a clear broad P 2p peak at about 134 eV. Further the film composition varied with the substrate temperature. The average visible transmittance calculated in the wavelength ranging 400-600 nm was more than 60\%. The optical band gap calculated from the absorption coefficient was about 3.2 eV. The Hall measurements confirm the n-type conductivity of the films. The carrier concentration in the films decreases with the increase of substrate temperature. The study is helpful for understanding the properties of P-doped ZnO films sputtered at lower substrate temperature and achieving p type ZnO films at lower temperature.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-80053999007\&partnerID=40\&md5=00efb945feb37c4064548bff3e9bc1c8}, author = {Wang, J.a b , Li, M.a , Sallet, V.c , Rego, A.d , Martins, R.b , Fortunato, E.b} } @article {Nunes2001139, title = {Properties presented by tin oxide thin films deposited by spray pyrolysis}, journal = {Solid State Phenomena}, volume = {80-81}, year = {2001}, note = {

cited By 0

}, pages = {139-144}, abstract = {

Thin films of SnO2 deposited by spray pyrolysis as a function of temperature and the carrier gas flow have been produced, in order to evaluate the adequate deposition parameters for application in optoelectronic devices. The characterisation was centred mainly onto the structural, electrical and optical properties of the films. The obtained results showed that the films produced at 450{\textdegree}C and a gas flow of 101/min (as deposited) present an average transmittance (visible spectrum) of 90\% and a bulk resistivity of 3.2{\texttimes}10-3 Ωcm.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034836713\&partnerID=40\&md5=8726531323645940e4e16ed4d9b7e26a}, author = {Nunes, P., Fortunato, E., Vilarinho, P., Martins, R.} } @article {Nunes2002424, title = {Properties presented by ZnO thin films deposited by magnetron sputtering and spray pyrolysis}, journal = {Key Engineering Materials}, volume = {230-232}, year = {2002}, note = {

cited By 2

}, pages = {424-427}, abstract = {

The most common techniques used to produce ZnO thin films are the spray pyrolysis and the magnetron sputtering techniques, low and high cost processes respectively. The aim of this work is to compare the properties of the films produced by these two techniques. The predominant difference observed was on the morphological properties. The films produced by spray pyrolysis have a rougher surface than the ones obtained by sputtering. Also the effect of the thermal annealing treatment is much more prononnced for the ZnO thin films produced by spray pyrolysis. After heat treatment films exhibit similar electrical properties and their application to optoelectronic devices is demonstrated.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036430522\&partnerID=40\&md5=e59655559d6bc60aefd197dd3194f8bf}, author = {Nunes, P., Fortunato, E., Martins, R., Vilarinho, P.} } @article {Cramer2016, title = {Radiation-Tolerant Flexible Large-Area Electronics Based on Oxide Semiconductors}, journal = {Advanced Electronic Materials}, volume = {2}, number = {7}, year = {2016}, note = {

cited By 0

}, abstract = {

Large-area electronics for applications in environments with radioactive contamination or medical X-ray detectors require materials and devices resistant to continuous ionizing radiation exposure. Here the superior X-ray radiation hardness of oxide thin film transistors (TFTs) based on gallium-indium-zinc oxide is demonstrated, when compared to organic ones. In the experiments both TFTs are subjected to X-ray radiation and their performances are monitored as a function of total ionizing dose. Flexible oxide TFTs maintain a constant mobility of 10 cm2 V-1 s-1 even after exposure to doses of 410 krad(SiO2), whereas organic TFTs lose 55\% of their transport performance. The exceptional resistance of oxide semiconductors ionization damage is attributed to their intrinsic properties such as independence of transport on long-range order and large heat of formation. {\textcopyright} 2016 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim

}, doi = {10.1002/aelm.201500489}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978384040\&partnerID=40\&md5=5ed8ff5e9a877ccad4f5f1ac7cf1c671}, author = {Cramer, T.a , Sacchetti, A.a , Lobato, M.T.b , Barquinha, P.b , Fischer, V.c , Benwadih, M.c , Bablet, J.c , Fortunato, E.b , Ma} } @article {Branquinho201144, title = {Real-time monitoring of PCR amplification of proto-oncogene c-MYC using a Ta2O5 electrolyte-insulator-semiconductor sensor}, journal = {Biosensors and Bioelectronics}, volume = {28}, number = {1}, year = {2011}, note = {

cited By 8

}, pages = {44-49}, abstract = {

We present a new approach for real-time monitoring of PCR amplification of a specific sequence from the human c-MYC proto-oncogene using a Ta 2O 5 electrolyte-insulator-semiconductor (EIS) sensor. The response of the fabricated EIS sensor to cycle DNA amplification was evaluated and compared to standard SYBR-green fluorescence incorporation, showing it was possible to detect DNA concentration variations with 30mV/μM sensitivity. The sensor{\textquoteright}s response was then optimized to follow in real-time the PCR amplification of c-MYC sequence from a genomic DNA sample attaining an amplification profile comparable to that of a standard real-time PCR. Owing to the small size, ease of fabrication and low-cost, the developed Ta 2O 5 sensor may be incorporated onto a microfluidic device and then used for real-time PCR. Our approach may circumvent the practical and economical obstacles posed by current platforms that require an external fluorescence detector difficult to miniaturize and incorporate into a lab-on-chip system. {\textcopyright} 2011 Elsevier B.V.

}, doi = {10.1016/j.bios.2011.06.039}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-80052377197\&partnerID=40\&md5=15054a62c7e299130f0507574dd2403d}, author = {Branquinho, R.a b , Veigas, B.c , Pinto, J.V.a , Martins, R.a , Fortunato, E.a , Baptista, P.V.c} } @article {Fortunato2005205, title = {Recent advances in ZnO transparent thin film transistors}, journal = {Thin Solid Films}, volume = {487}, number = {1-2}, year = {2005}, note = {

cited By 264

}, pages = {205-211}, abstract = {

Zinc oxide is a well-known wide band gap semiconductor material (3.4 eV at room temperature, in the crystalline form), which has many applications, such as for transparent conductors, varistors, surface acoustic waves, gas sensors, piezoelectric transducers and UV detectors. More recently, it is attracting considerable attention for its possible application to thin film transistors. In this paper, we present some of the recent results already obtained as well as the ones that are being developed in our laboratory. The main advantage presented by these new thin film transistors is the combination of high channel mobility and transparency produced at room temperature which makes these thin film transistors a very promising low cost device for the next generation of invisible and flexible electronics. Moreover, the processing technology used to fabricate this device is relatively simple and it is compatible with inexpensive plastic/flexible substrate technology. {\textcopyright} 2005 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2005.01.066}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-22944469098\&partnerID=40\&md5=c7a515feddc228eb595591bf73e593a2}, author = {Fortunato, E., Barquinha, P., Pimentel, A., Gon{\c c}alves, A., Marques, A., Pereira, L., Martins, R.} } @article {Martins20132153, title = {Recyclable, flexible, low-power oxide electronics}, journal = {Advanced Functional Materials}, volume = {23}, number = {17}, year = {2013}, note = {

cited By 47

}, pages = {2153-2161}, abstract = {

The ability to process and dimensionally scale field-effect transistors with and on paper and to integrate them as a core component for low-power-consumption analog and digital circuits is demonstrated. Low-temperature-processed p- and n-channel integrated oxide thin-film transistors in the complementary metal oxide semiconductor (CMOS) inverter architecture are seamlessly layered on mechanically flexible, low-cost, recyclable paper substrates. The possibility of building these circuits using low-temperature processes opens the door to new applications ranging from smart labels and sensors on clothing and packaging to electronic displays printed on paper pages for use in newspapers, magazines, books, signs, and advertising billboards. Because the CMOS circuits reported constitute fundamental building blocks for analog and digital electronics, this development creates the potential to have flexible form factor computers seamlessly layered onto paper. The holistic approach of merging low-power circuitry with a recyclable substrate is an important step towards greener electronics. Copyright {\textcopyright} 2013 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/adfm.201202907}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84877285565\&partnerID=40\&md5=45b0a2bf92fd8142794559dc192b49f9}, author = {Martins, R.F.P.a , Ahnood, A.b , Correia, N.a , Pereira, L.M.N.P.a , Barros, R.a , Barquinha, P.M.C.B.a , Costa, R.a , Ferreira,} } @article {Chitanu201132, title = {RF magnetron sputtering deposition of AZO thin films}, journal = {Metalurgia International}, volume = {16}, number = {12}, year = {2011}, note = {

cited By 0

}, pages = {32-34}, abstract = {

Doped zinc oxide with aluminium are attractive alternative material as transparent conducting electrode because they are nontoxic and inexpensive compared with indium tin oxide (ITO) for diffrent applications: solar cells, tft. Transparent aluminumdoped zinc oxide (AZO) thin films were deposited on glass substrates by RF magnetron sputtering at room temperature and 100W from ceramic target ZnO-Al2O3 (98:2 weight percent). The structural, electrical and optical properties of these films were characterized as a function of deposition pressure. AZO films with low resistivity 2.02{\texttimes}10-3 Ωcm and high transmittance (over 80\% in vizible range) were thus prepared with a deposition pressure of 3 mTorr.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-80052842437\&partnerID=40\&md5=01056b223ec0593e280d1d29f87d0822}, author = {Chitanu, E.a , Barros, R.b c , Ionita, G.d , Martins, R.b , Fortunato, E.b} } @article {Elangovan2009726, title = {RF sputtered wide work function indium molybdenum oxide thin films for solar cell applications}, journal = {Solar Energy}, volume = {83}, number = {5}, year = {2009}, note = {

cited By 20

}, pages = {726-731}, abstract = {

Indium molybdenum oxide (IMO) thin films were deposited by RF magnetron sputtering on glass substrates at room temperature. The deposition and argon partial pressures were maintained at 6.0 {\texttimes} 10-1 Pa and 3.0 {\texttimes} 10-1 Pa, respectively. The oxygen partial pressure (OPP) was varied in the range 1.0-6.0 {\texttimes} 10-3 Pa. The films were sputtered at 40 W for 30 min using the target consisted In2O3 (98 wt\%): Mo (2 wt\%). The films are polycrystalline with a slight preferential orientation along (2 2 2) plane. The crystallinity is increased with the increasing OPP. The negative sign of Hall coefficient confirmed the n-type conductivity. A maximum mobility \~{}19 cm2 V-1 s-1 is obtained for the films deposited with OPP of 3.6 {\texttimes} 10-3 Pa. The average visible transmittance calculated in the wavelength ranging 500-800 nm is ranging between 2\% and 77\%. The optical band gap calculated from the absorption data is varied between 3.69 and 3.91 eV. A striking feature is that the work function of the films is wide ranging 4.61-4.93 eV. A possibility of using the produced IMO films as transparent conducting oxide in photovoltaic applications such as organic solar cells is discussed in this article. {\textcopyright} 2008 Elsevier Ltd. All rights reserved.

}, doi = {10.1016/j.solener.2008.11.001}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-63449083309\&partnerID=40\&md5=bf7aba3387a28871b78635b2446de350}, author = {Elangovan, E., Gon{\c c}alves, G., Martins, R., Fortunato, E.} } @article {Ara{\'u}jo2013, title = {Role of a disperse carbon interlayer on the performances of tandem a-Si solar cells}, journal = {Science and Technology of Advanced Materials}, volume = {14}, number = {4}, year = {2013}, note = {

cited By 4

}, abstract = {

We report the effect of a disperse carbon interlayer between the n-a-Si:H layer and an aluminium zinc oxide (AZO) back contact on the performance of amorphous silicon solar cells. Carbon was incorporated to the AZO film as revealed by x-ray photoelectron spectroscopy and energy-dispersive x-ray analysis. Solar cells fabricated on glass substrates using AZO in the back contact performed better when a disperse carbon interlayer was present in their structure. They exhibited an initial efficiency of 11\%, open-circuit voltage Voc = 1.6 V, short-circuit current JSC = 11 mA cm -2 and a filling factor of 63\%, that is, a 10\% increase in the J SC and 20\% increase in the efficiency compared to a standard solar cell. {\textcopyright} 2013 National Institute for Materials Science.

}, doi = {10.1088/1468-6996/14/4/045009}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84884896949\&partnerID=40\&md5=dd6f5690a09b79cb618e45d19603a7b9}, author = {Ara{\'u}jo, A.a , Barros, R.a , Mateus, T.a , Gaspar, D.a , Neves, N.b , Vicente, A.a , Filonovich, S.A.a , Barquinha, P.a , Fortuna} } @article {Canhola2005271, title = {Role of annealing environment on the performances of large area ITO films produced by rf magnetron sputtering}, journal = {Thin Solid Films}, volume = {487}, number = {1-2}, year = {2005}, note = {

cited By 36

}, pages = {271-276}, abstract = {

This paper presents the role of the deposition pressure and the rf power density on the optimization of the electrical, optical and structural properties of large area (30{\texttimes}40 cm2) indium-tin oxide films produced by rf magnetron sputtering, with growth rates exceeding 30 nm/min. The films were produced at room temperature under reactive plasma, followed by a thermal annealing in air or formic gas. The best films{\textquoteright} uniformity (<={\textpm}5\%), compactness and surface smoothness (preferential growth orientation along (222)); and electro-optical properties (resistivity and mobility, respectively, of about 7{\texttimes}10-4 Ω cm and 19.6 cm2 V -1 s-1, with transmittance of about 92\%) were achieved using a rf power density of 0.92 W cm-2 and a pressure of 8.5{\texttimes}10-2 Pa, followed by its annealing in air by about 2 h at 773 K. {\textcopyright} 2005 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2005.01.078}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-22944484060\&partnerID=40\&md5=7dee63dd81343f374728d1fce912d980}, author = {Canhola, P.a , Martins, N.a , Raniero, L.b , Pereira, S.b , Fortunato, E.c , Ferreira, I.b , Martins, R.b} } @article {Raniero2005170, title = {Role of buffer layer on the performances of amorphous silicon solar cells with incorporated nanoparticles produced by plasma enhanced chemical vapor deposition at 27.12 MHz}, journal = {Thin Solid Films}, volume = {487}, number = {1-2}, year = {2005}, note = {

cited By 22

}, pages = {170-173}, abstract = {

The aim of this paper is to present results concerning the role of the buffer layer on pin devices, deposited in a single chamber for plasma enhanced chemical vapor deposition, using high hydrogen dilution and pressures at 27.12 MHz. By doing so, we allow the incorporation of nanoparticles into the i-layer, during plasma process. The results show solar cells with 8.8\% efficiency with a collection efficiency of 95\% in the blue region of the spectra. Apart from that, the results from impedance spectroscopy, imaginary impedance vs. real impedance, show difference of a semicircle radius as function of sample temperatures, which could be explained by total device series resistance variation. {\textcopyright} 2005 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2005.01.059}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-22944443594\&partnerID=40\&md5=9262a48e83fff3e7f679e6a0caf0753e}, author = {Raniero, L., Zhang, S., {\'A}guas, H., Ferreira, I., Igreja, R., Fortunato, E., Martins, R.} } @article {Olziersky2011512, title = {Role of Ga 2O 3-In 2O 3-ZnO channel composition on the electrical performance of thin-film transistors}, journal = {Materials Chemistry and Physics}, volume = {131}, number = {1-2}, year = {2011}, note = {

cited By 31

}, pages = {512-518}, abstract = {

In this work we present a study aiming to determine the role of Ga2O3-In2O3-ZnO (GIZO) channel layer composition on the electrical performance and stability exhibited by thin-film transistors (TFTs). The GIZO films were obtained by magnetron sputtering using ceramic targets of different compositions (Ga:In:Zn = 2:2:1, 2:2:2, 2:4:1 and 2:4:2 at.). Structural analysis corroborates the fully amorphous character of the GIZO deposited layers. For the target compositional range used we observe a Zn deficiency on the produced films, which affects the In/Ga atomic concentration ratios. Resistivity and mobility are found to show a general trend against the measured In/Ga ratio that reveals the role played by In and Ga cations on the transport mechanisms. Targets with increased In concentrations (2:4:1 and 2:4:2) allow to obtain the best TFT performances with field effect mobilities reaching values of 53.0 and 51.7cm2 V-1 s-1, respectively. In addition, the In-richer GIZO compositions result in considerably more stable TFTs, especially under positive gate bias stress conditions. Finally, it is verified that by using a target with a slightly lower In atomic composition (2:4:2 in comparison to 2:4:1), good stability and mobility can be achieved with potentially lower material costs.{\textcopyright} 2011 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.matchemphys.2011.10.013}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84860761855\&partnerID=40\&md5=396450f340d19a8f0b0df4c37031411f}, author = {Olziersky, A.a , Barquinha, P.b , Vil{\`a}, A.a , Magana, C.a , Fortunato, E.b , Morante, J.R.a c , Martins, R.b} } @article {Raniero2006295, title = {Role of hydrogen plasma on electrical and optical properties of ZGO, ITO and IZO transparent and conductive coatings}, journal = {Thin Solid Films}, volume = {511-512}, year = {2006}, note = {

cited By 65

}, pages = {295-298}, abstract = {

In this paper we study the electro-optical behaviour and the structure of different TCOs, namely the ZGO, ITO and IZO films before and after being submitted to different hydrogen plasma power densities, for times up to 60 s, aiming their use in a/nc-Si:H solar cells. The results achieved show that ZGO films do not reduce for all plasma conditions used and so, the solar cells produced evidence high current density, about 17\% larger that the one recorded in the other TCOs. Besides that, by combining the electrical and optical characteristics of the films through a figure of merit, the data reveal that for the ITO and IZO films even when exposed to very low hydrogen power plasma, the figure of merit is reduced up to 50\%. {\textcopyright} 2005 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2005.12.057}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33747455324\&partnerID=40\&md5=754f82b1738c5f5fc1c319ea3a453918}, author = {Raniero, L., Ferreira, I., Pimentel, A., Gon{\c c}alves, A., Canhola, P., Fortunato, E., Martins, R.} } @article {Raniero200663, title = {Role of hydrogen plasma on the electrical and optical properties of indium zinc transparent conductive oxide}, journal = {Materials Science Forum}, volume = {514-516}, number = {PART 1}, year = {2006}, note = {

cited By 1

}, pages = {63-67}, abstract = {

In this work we studied the influence of the power density of hydrogen plasma on electrical and optical properties (Hall mobility, free carrier concentration, sheet resistance, optical transmittance and a.c. impedance) of indium zinc oxide films, aiming to determine their chemical stability. This is an important factor for the optimization of amorphous/nanocrystalline p-i-n hydrogenated silicon (a/nc-Si:H) solar cells, since they should remain chemically highly stable during the p layer deposition. To perform this work the transparent conductive oxide was exposed to hydrogen plasma at substrate temperature of 473 K, 87 Pa of pressure and 20 seem of hydrogen flow. The results achieved show that IZO films were reduced for all plasma conditions used, which leads mainly to a decrease on films transmittance. For the lowest power density used in the first minute of plasma exposition the transmittance of the IZO films decreases about 29\%.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-37849012918\&partnerID=40\&md5=3a09493cb8d5263a648a193e761b03f9}, author = {Raniero, L.a , Gon{\c c}alves, A.a , Pimentel, A.a , Zhang, S.a , Ferreira, I.a , Vilarinho, P.M.b , Fortunato, E.a , Martins, R.a} } @article {Martins2001165, title = {Role of ion bombardment and plasma impedance on the performances presented by undoped a-Si:H films}, journal = {Thin Solid Films}, volume = {383}, number = {1-2}, year = {2001}, note = {

cited By 10

}, pages = {165-168}, abstract = {

The aim of this paper was to present results of the role of the d.c. grid bias on the silane plasma impedance and its I-V characteristics to grow undoped amorphous silicon (a-Si:H) films by plasma enhanced chemical vapour deposition (PECVD) in conditions where some nanoparticles can be formed in the growth region of the deposition process, under proper ion bombardment. The results achieved show that the performances of the films produced are dependent on the self bias voltage that can present photosensitivities of approximately 107 (two orders of magnitude larger than the one exhibited by films grown under conventional conditions) with density of states determined by the constant photocurrent method below 4{\texttimes}1015 cm-3. Apart from that, the films grown are less affected by light soaking than the conventional films.

}, doi = {10.1016/S0040-6090(00)01597-2}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035246781\&partnerID=40\&md5=b1bee49f62f56478263a2edf428c9c6e}, author = {Martins, R., �?guas, H., Ferreira, I., Silva, V., Cabrita, A., Fortunato, E.} } @article {{\'A}guas2000247, title = {Role of ion bombardment on the properties of a-Si : H films}, journal = {Vacuum}, volume = {60}, number = {1-2}, year = {2000}, note = {

cited By 10

}, pages = {247-254}, abstract = {

In this work we present a study of influence of ion bombardment on the optical, electrical and compositional properties of the intrinsic amorphous silicon films deposited in a modified triode plasma-enhanced chemical vapour deposition (PECVD) reactor. The application of a DC voltage to a grid placed in front of the r.f. electrode allowed us to control the energy and polarity of the ions striking the substrate during film growth. The results show a variation by two orders of magnitude in the dark conductivity from 10-10 to 6.2 {\texttimes} 10-12 (Ω cm)-1, while the photosensitivity varied from 2 {\texttimes} 105 to 2 {\texttimes} 107. A process plasma that takes place in the γ-type regime was associated with the use of a negative bias, while a process plasma like the one of the α-type regime was associated with the use of a positive bias. The films deposited with a bias ≈ 38 V are highly intrinsic and the abrupt change in the conductivity properties observed at this bias is attributed to a change in the density of the states ascribed to the position of the Fermi level. That is, a precise control of the energy of the ions striking the substrate during the film growth leads to improved film optoelectronic properties, very important for device applications. {\textcopyright} 2001 Elsevier Science Ltd. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035157422\&partnerID=40\&md5=5ff49f3d58b4a04f4a183290a1048a2a}, author = {{\'A}guas, H., Martins, R., Fortunato, E.} } @article {Martins200737, title = {Role of order and disorder in covalent semiconductors and ionic oxides used to produce thin film transistors}, journal = {Applied Physics A: Materials Science and Processing}, volume = {89}, number = {1}, year = {2007}, note = {

cited By 30

}, pages = {37-42}, abstract = {

This paper aims to discuss the effect of order and disorder on the electrical performances of covalent silicon semiconductors and ZnO based ionic oxide semiconductors used as active channel layers in thin film transistors. The effect of disorder on covalent semiconductors directly affects their electrical transport properties due to the asymmetric behaviour of sp states, while in ionic oxide semiconductors it is found that this effect is small due to the fact that angular disorder has no effect on the spherical symmetry of s states. To this we must add that the mobility of carriers in both systems is quite different, being also affected by electron-phonon interactions (weak in silicon and strong in ionic oxides leading to formation of polarons). Besides, the impurity doping effect and the presence of vacancies in disordered silicon and in ionic oxides behave differently, which will influence the thin film properties and so, the performances of the devices produced. {\textcopyright} 2007 Springer-Verlag.

}, doi = {10.1007/s00339-007-4038-1}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-36048995648\&partnerID=40\&md5=27a522d0a8ec3b87f40a1a59e8c10175}, author = {Martins, R., Barquinha, P., Pereira, L., Ferreira, I., Fortunato, E.} } @article {Martins2007, title = {Role of order and disorder on the electronic performances of oxide semiconductor thin film transistors}, journal = {Journal of Applied Physics}, volume = {101}, number = {4}, year = {2007}, note = {

cited By 138

}, abstract = {

The role of order and disorder on the electronic performances of n -type ionic oxides such as zinc oxide, gallium zinc oxide, and indium zinc oxide used as active (channel) or passive (drain/source) layers in thin film transistors (TFTs) processed at room temperature are discussed, taking as reference the known behavior observed in conventional covalent semiconductors such as silicon. The work performed shows that while in the oxide semiconductors the Fermi level can be pinned up within the conduction band, independent of the state of order, the same does not happen with silicon. Besides, in the oxide semiconductors the carrier mobility is not bandtail limited and so disorder does not affect so strongly the mobility as it happens in covalent semiconductors. The electrical properties of the oxide films (resistivity, carrier concentration, and mobility) are highly dependent on the oxygen vacancies (source of free carriers), which can be controlled by changing the oxygen partial pressure during the deposition process and/or by adding other metal ions to the matrix. In this case, we make the oxide matrix less sensitive to the presence of oxygen, widening the range of oxygen partial pressures that can be used and thus improving the process control of the film resistivity. The results obtained in fully transparent TFT using polycrystalline ZnO or amorphous indium zinc oxide (IZO) as channel layers and highly conductive poly/nanocrystalline ZGO films or amorphous IZO as drain/source layers show that both devices work in the enhancement mode, but the TFT with the highest electronic saturation mobility and on/off ratio 49.9 cm2 V s and 4.3{\texttimes} 108, respectively, are the ones in which the active and passive layers are amorphous. The ZnO TFT whose channel is based on polycrystalline ZnO, the mobility and on/off ratio are, respectively, 26 cm2 V s and 3{\texttimes} 106. This behavior is attributed to the fact that the electronic transport is governed by the s -like metal cation conduction bands, not significantly affected by any type of angular disorder promoted by the 2p O states related to the valence band, or small amounts of incorporated metal impurities that lead to a better control of vacancies and of the TFT off current. {\textcopyright} 2007 American Institute of Physics.

}, doi = {10.1063/1.2495754}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33847634295\&partnerID=40\&md5=cd422aeccc2744cfaede8d2e41701358}, author = {Martins, R.b , Barquinha, P.a , Ferreira, I.a , Pereira, L.a , Gonalves, G.a , Fortunato, E.a} } @article {Martins19952199, title = {Role of oxygen partial pressure on the properties of doped silicon oxycarbide microcrystalline layers produced by spatial separation techniques}, journal = {Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films}, volume = {13}, number = {4}, year = {1995}, note = {

cited By 7

}, pages = {2199-2209}, abstract = {

The aim of this work is to present experimental data concerning the role of the oxygen partial pressure during the production process on the properties (structure, morphology, composition, and transport properties) exhibited by doped microcrystalline silicon oxycarbide films. The films were produced by a two consecutive decomposition and deposition chamber system, where a spatial separation between the plasma and the growth regions is achieved. The films produced by this technique are highly conductive and highly transparent with suitable properties for optoelectronic applications requiring wide band-gap and low-conductivity materials. {\textcopyright} 1995, American Vacuum Society. All rights reserved.

}, doi = {10.1116/1.579543}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-21844500459\&partnerID=40\&md5=3a25dd08a4b21cfd56fd6e788844183c}, author = {Martins, R.a , Vieira, M.b , Ferreira, I.a , Fortunato, E.a} } @article {Gon{\c c}alves2011340, title = {Role of room temperature sputtered high conductive and high transparent indium zinc oxide film contacts on the performance of orange, green, and blue organic light emitting diodes}, journal = {Plasma Processes and Polymers}, volume = {8}, number = {4}, year = {2011}, note = {

cited By 16

}, pages = {340-345}, abstract = {

The core of this paper concerns the use of an amorphous transparent conductive oxide (a-TCO), whose performance is on par with the classical indium tin oxide (ITO) films as a transparent contact in organic light emitting diodes (OLEDs). The main advantage of indium zinc oxide (IZO) films relies on their amorphous structure and high mobility that turns them likely to be used with high conductivity and high transmittance even at the infrared region. The mobility of IZO films (47.8 cm2 {\textperiodcentered} V-1 {\textperiodcentered} s-1) surpasses the one exhibited by ITO films (26.4 cm2 {\textperiodcentered} V-1 {\textperiodcentered} s-1), which along with its smoother surface and better current distribution plays an important role on OLEDs performance. Besides their similar turn-on voltage, the devices using IZO anodes exhibit higher power efficiency than the ITO ones, which is 66, 18, and 62\% for orange, green, and blue OLEDs, respectively. These results suggest that IZO can potentially be applied as an anode in full color displays based on OLEDs. {\textcopyright} 2011 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/ppap.201000149}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79953847269\&partnerID=40\&md5=8ce6df97172f6160719319f9eb4225ad}, author = {Gon{\c c}alves, G.a , Grasso, V.b , Barquinha, P.a , Pereira, L.a , Elamurugu, E.a , Brignone, M.b , Martins, R.a , Lambertini, V.b ,} } @article {Martins2000275, title = {Role of soldering parameters on the electrical performances presented by Cu-Sn-Cu joints used in power diodes}, journal = {Materials Science and Engineering A}, volume = {288}, number = {2}, year = {2000}, note = {

cited By 1

}, pages = {275-279}, abstract = {

The effects of Sn thickness electrodeposited over Cu on the structural and morphological performance of the joints formed were investigated. The electrical stability of the joints formed was analyzed under extreme aggressive conditions. Results indicated that the proposed soldering technology greatly satisfied the demands concerning soldering specifications.

}, doi = {10.1016/S0921-5093(00)00871-6}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034272895\&partnerID=40\&md5=80ab0d0cb20cf94ac28fdb70bd6aa899}, author = {Martins, R.a , Ferreira, J.a , Gon{\c c}alves, C.a , Nunes, P.a , Fortunato, E.a , Marv{\~a}o, A.P.b , Martins, J.I.c} } @article {Barquinha20081905, title = {The role of source and drain material in the performance of GIZO based thin-film transistors}, journal = {Physica Status Solidi (A) Applications and Materials Science}, volume = {205}, number = {8}, year = {2008}, note = {

cited By 23

}, pages = {1905-1909}, abstract = {

Indium tin oxide (ITO) has been used as the prefered electrode material for the emerging area of transparent electronics, namely for thin-film transistors (TFTs) based on oxide semiconductors. This work pretends to investigate different materials to replace ITO in inverted-staggered TFTs based on gallium-indium-zinc oxide (GIZO), one of the most promissing oxide semiconductors for TFTs. The analyzed electrode materials are indium-zinc oxide (IZO), Ti, Mo and Ti/Au. Devices are analyzed with special focus on the contact resistance fundamentals, including the extraction of source/ drain series resistances and TFTs intrinsic parameters, such as intrinsic mobility (p\) and intrinsic threshold voltage (V Ti). The obtained contact resistance values are between 10 kΩ and 20 kΩ, and the best devices have field effect mobility ((μ FE) close to 25 cm 2/V s and on/off ratio close to 10 8. {\textcopyright} 2008 WILEY-VCH Verlag GmbH \& Co. KGaA.

}, doi = {10.1002/pssa.200778940}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-54249108508\&partnerID=40\&md5=a771682ecd692c490e5c28e4a3b8f77e}, author = {Barquinha, P.a , Vila, A.b , Gon{\c c}alves, G.a , Pereira, L.a , Martins, R.a , Morante, J.b , Fortunate, E.a} } @article {Pereira2004112, title = {Role of substrate on the growth process of polycrystalline silicon thin films by low-pressure chemical vapour deposition}, journal = {Materials Science Forum}, volume = {455-456}, year = {2004}, note = {

cited By 0

}, pages = {112-115}, abstract = {

This paper deals with the role the substrate on the structure of undoped and n-doped polycrystalline silicon (poly-Si) films produced by Low Pressure Chemical Vapour Deposition (LPCVD). The structural and electrical properties of the films deposited on glass, glass covered with molybdenum (Mo), oxidised crystalline silicon and oxidised crystalline silicon covered with Mo were analysed using X-ray diffraction and Spectroscopic Ellipsometry, dark conductivity and Hall effect measurements. Undoped poly-Si films deposited over Mo present modifications in the crystalline structure relatively to those deposited on the other substrates. The presence of Mo changes the preferential growth orientation, enhancing the Si {111} grains orientation, leading to more compact films. The electrical measurements also confirm that the films grown on Mo substrates present better characteristics. Some differences are also observed during the initial growth stages when using glass or oxidised silicon. Very thin n-doped films present a less effective doping effect when deposited on oxidised silicon than the ones deposited on glass substrates.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-3142707953\&partnerID=40\&md5=c9267d26c3ca44b987d794e9bc9646a2}, author = {Pereira, L., {\'A}guas, H., Raniero, L., Martins, R.M.S., Fortunate, E., Martins, R.} } @article {Fortunato19962702, title = {Role of the collecting resistive layer on the static characteristics of a 1D a-Si:H thin film position sensitive detector}, journal = {Review of Scientific Instruments}, volume = {67}, number = {8}, year = {1996}, note = {

cited By 13

}, pages = {2702-2707}, abstract = {

The aim of this work is to present an analytical model able to interpret the role of the thin collecting resistive layer on the static performances exhibited by 1D amorphous silicon hydrogenated p-i-n thin film position sensitive detectors. The data obtained show that the devices present a linearity and a spatial resolution, of respectively, better than 99\% and 20 μm for a spatial detection limit of about 80 mm, highly dependent on the characteristics exhibited by the collecting resistive layer that should have sheet resistivities in the range of 10 to 103 Ω/sq, as predicted by the model proposed. {\textcopyright} 1996 American Institute of Physics.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030216709\&partnerID=40\&md5=6449c77f3ffdb5e3cb4247b8d03e770c}, author = {Fortunato, E., Martins, R.} } @article {Cabrita2002559, title = {Role of the density of states in the colour selection of the collection spectrum of amorphous silicon-based Schottky photodiodes}, journal = {Key Engineering Materials}, volume = {230-232}, year = {2002}, note = {

cited By 0

}, pages = {559-562}, abstract = {

This work deals with the study of the role of intra-gap density of states on the colour selection of the collection spectrum of glass/ITO/a-Six:C1-x:H/Al Schottky photodiodes. In order to optimise the voltage colour selection and to study the influence of intragap density of states in the final device performances, different undoped a-Six:C1-x:H films (1 μm thick) have been produced in a conventional Plasma Enhanced Chemical Vapour Deposition (PECVD) system using silane and a controlled mixtures of silane and methane as gas sources. The properties of the films were analysed by dark conductivity measurements, infrared spectroscopy, visible spectroscopy and constant photocurrent method (CPM), to determine the valence controllability and to correlate the silicon carbide layer composition with the performances of the devices. The performances obtained concerning the spectral response of the devices were correlated with the carbon content and the density of states of the a-Six:C1-x:H films.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036436608\&partnerID=40\&md5=623b1d01752f06b7a1d1c616675ff0fb}, author = {Cabrita, A., Pereira, L., Brida, D., Silva, V., Ferreira, I., Fortunato, E., Martins, R.} } @article {Martins1998901, title = {Role of the deposition conditions on the properties presented by nanocrystallite silicon films produced by hot wire}, journal = {Journal of Non-Crystalline Solids}, volume = {227-230}, number = {PART 2}, year = {1998}, note = {

cited By 11

}, pages = {901-905}, abstract = {

The aim of this work is to study the role of hydrogen dilution and filament temperature on the properties of nanocrystalline silicon thin films (undoped and doped) produced by the hot wire technique. These deposition parameters are correlated to the film{\textquoteright}s structure, composition and electro-optical properties with special emphasis on boron doped nanocrystalline silicon carbide reported here. {\textcopyright} 1998 Elsevier Science B.V. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032064398\&partnerID=40\&md5=db1fb43a6d45152aeda593bcda733fbe}, author = {Martins, R., Ferreira, I., Fernandes, F., Fortunato, E.} } @article {Martins1997259, title = {Role of the deposition parameters in the uniformity of films produced by the plasma-enhanced chemical vapour deposition technique}, journal = {Philosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties}, volume = {76}, number = {3}, year = {1997}, note = {

cited By 6

}, pages = {259-272}, abstract = {

The objective of this work is to present an analytical model able to interpret the experimental dependence of the uniformity of films produced by the plasma-enhanced chemical vapour deposition technique on the deposition parameters (discharge pressure, gas flow temperature and rf power density). The model proposed is based on the Navier-Stokes equations applied to a gas flow considered to be quasi-incompressible and quasi-inviscous, whenever the Mach number is below 0{\textperiodcentered}3. This condition leads to the establishment of the proper quasisteady-state gas flow equations, and the corresponding equations of energy and momentum balance ascribed to the mass profile of the species formed, under the presence of a low-rf-power plasma density, are able to predict the uniformity distribution of the film over the entire deposited substrate area.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0342478341\&partnerID=40\&md5=2ab85d8478085bcd75dc19791a2006d1}, author = {Martins, R., Ma{\c c}arico, A., Ferreira, I., Fidalgo, J., Fortunato, E.} } @article {Ferreira2001141, title = {Role of the gas pressure and hydrogen dilution on the properties of large area nanocrystalline p-type silicon films produced by hot wire technique}, journal = {Materials Science and Engineering C}, volume = {15}, number = {1-2}, year = {2001}, note = {

cited By 0

}, pages = {141-144}, abstract = {

This paper reports results on the role of high hydrogen dilution (above 80\%) on the electro-optical and structural properties of boron doped silicon films produced by hot wire chemical vapor deposition (HW-CVD) technique, keeping constant the filament temperature. The structural, compositional, morphological, electrical and optical properties achieved show that the films present excellent homogeneity over the entire 10 x 10 cm deposited area. These results were obtained for films produced at gas pressures below 66.5 Pa, in spite of the high flow rate used. {\textcopyright} 2001 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0928-4931(01)00250-8}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034853144\&partnerID=40\&md5=38a6e4683744096c5cdf9a6b9923dd61}, author = {Ferreira, I., Cabrita, A., Braz Fernandes, F., Fortunato, E., Martins, R.} } @article {Martins200025, title = {Role of the gas temperature and power to gas flow ratio on powder and voids formation in films grown by PECVD technique}, journal = {Vacuum}, volume = {56}, number = {1}, year = {2000}, note = {

cited By 20

}, pages = {25-30}, abstract = {

This paper deals with the study of the role of gas temperature and of the ratio of r.f. power to gas flow on the particle{\textquoteright}s formation in amorphous silicon films grown by plasma enhanced chemical vapour deposition technique, by monitoring the plasma impedance behaviour under different process conditions. The aim is to determine in which conditions the particles formed do not deteriorate the performances of the films grown or even can lead to an improvement of the properties of the films deposited. The results achieved show the existence of two main boundary regions (β- and θ-regions) separating the so-called α-regime (no powder formed) from the γ-regime (powder formed). Those regions are reached either by heating the gas, changing the gas pressure or using high power to gas flow ratios. In the β-region the probability of incorporating nanoparticles in the films is low and the films exhibit properties similar to those of the ones grown in the α-regime, with a low density of voids incorporated. In the θ-region small nanoparticles can be incorporated leading to films with density of states below 5{\texttimes}1015 cm-3, widened Urbach energies and photosensitivities about two orders of magnitude larger than that of conventional amorphous silicon grown in the α-regime. {\textcopyright} 2000 Elsevier Science Ltd.

}, doi = {10.1016/S0042-207X(99)00158-X}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033886444\&partnerID=40\&md5=98539ac1cae515cc9744055a86da02c0}, author = {Martins, R., Silva, V., Ferreira, I., Domingues, A., Fortunato, E.} } @article {Martins2000272, title = {Role of the gas temperature and power to gas flow ratio on powder formation and properties of films grown by the PECVD technique}, journal = {Materials Science and Engineering B: Solid-State Materials for Advanced Technology}, volume = {69}, year = {2000}, note = {

cited By 6

}, pages = {272-277}, abstract = {

This paper deals with the study of the role of gas temperature and of the ratio of r.f. power to gas flow on the particle{\textquoteright}s formation in amorphous silicon films grown by the plasma enhanced chemical vapour deposition technique, by monitoring the plasma impedance behaviour under different process conditions. The results achieved show the existence of two main boundary regions separating the so-called α-regime (no powder formed) from the γ-regime (powder formed). Those regions are reached either by heating the gas, changing the gas pressure or using high power to gas flow ratios, corresponding to the establishment of a balance between the plasma resistance and the plasma reactance. In the β-region the probability to incorporate nanoparticles in the films is low and the films exhibit photosensitivity{\textquoteright}s of about 105 with density of states determined by the constant photocurrent method below 6{\texttimes}1015 cm-3 with Urbach energies below 50 meV. In the θ-region small nanoparticles can be incorporated leading to films with density of states below 3{\texttimes}1015 cm-3, with Urbach energies above 50 meV and photosensitivity{\textquoteright}s above 106, about two orders of magnitude larger than that of conventional amorphous silicon grown in the α-regime.

}, doi = {10.1016/S0921-5107(99)00307-4}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033895960\&partnerID=40\&md5=7a91bd106467457a0d3b6d0b471b2f68}, author = {Martins, R., Silva, V., Ferreira, I., Domingues, A., Fortunato, E.} } @article {Ferreira1999690, title = {Role of the hot wire filament temperature on the structure and morphology of the nanocrystalline silicon p-doped films}, journal = {Applied Surface Science}, volume = {144-145}, year = {1999}, note = {

cited By 7

}, pages = {690-696}, abstract = {

Nanocrystalline p-doped silicon films were deposited at low substrate temperatures (around 200{\textdegree}C) in a hot wire reactor. In this paper we present the results on the role of the hydrogen dilution and filament temperature on the film{\textquoteright}s structure, composition, morphology and transport properties. The film{\textquoteright}s structure changes from honeycomb-like to a granular needle shape as the filament temperature changes from about 2000{\textdegree}C and hydrogen dilution 87\%, to values above 2100{\textdegree}C and hydrogen dilution 90\%, respectively. The nanocrystalline silicon-based films produced have optical gaps varying from 1.6 to 1.95 eV, with conductivities up to 0.2 S cm-1 and grain sizes (obtained by X-ray diffraction) in the range of 10-30 nm. {\textcopyright} 1999 Elsevier Science B.V. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032647996\&partnerID=40\&md5=e622ef0150d01c94dafb520ea26ecf09}, author = {Ferreira, I., {\'A}guas, H., Mendes, L., Martins, R.} } @article {{\'A}guas2002220, title = {Role of the i layer surface properties on the performance of a-Si:H Schottky barrier photodiodes}, journal = {Sensors and Actuators, A: Physical}, volume = {99}, number = {1-2}, year = {2002}, note = {

cited By 2

}, pages = {220-223}, abstract = {

In this work, we study the influence of the hydrogenated amorphous silicon (a-Si:H) surface treatment on the J-V characteristics of a-Si:H/Pd Schottky barrier photodiodes. The a-Si:H surface were etched, thermally oxidised and wet oxidised by H2O2. The a-Si:H films were characterised by spectroscopic ellipsometry, were we found that all the oxidation techniques promote an increase of the surface oxide thickness that was confirmed by the increase of the barrier height. The highest barrier was achieved by the H2O2 oxidation where a value of 1.17 eV was found. As a result of the barrier height increase, the dark reverse current density decreases up to 10-10 A/cm2 and the signal to noise ratio increases up to 106. The open circuit voltage under AM1.5 illumination conditions also increases from 0.4 to 0.5 V. These results reveal the importance of the a-Si:H surface preparation prior to metallization to improve the Schottky photodiodes properties. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0924-4247(01)00892-5}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037198095\&partnerID=40\&md5=60ab192ed01f9ff46a623df0c76a8eac}, author = {{\'A}guas, H., Fortunato, E., Martins, R.} } @article {{\'A}guas2002587, title = {Role of the i-layer thickness in the performance of a-Si:H Schottky barrier photodiodes}, journal = {Key Engineering Materials}, volume = {230-232}, year = {2002}, note = {

cited By 0

}, pages = {587-590}, abstract = {

In this work we present the current/voltage characteristics of Si:H/Pd Schottky structures using high quality, low defect density amorphous silicon (a-Si:H) deposited by a non-conventional, modified triode PECVD method. This new configuration allows the deposition of compact and high quality a-Si:H with a photosensitivity of 107, yielding films with low bulk defects. AFM measurements also revealed that these films have a very smooth surface allowing a low defect interface between the metal and the a-Si:H. As a result, we show that by using these a-Si:H films and by proper control of the i-layer thickness the reverse dark current of the diode can be highly reduced achieving signal to noise ratio of 106, surpassing the results usually achieved by p-i-n structures.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036434959\&partnerID=40\&md5=77ba296f6b2c92661886596f29c42ee0}, author = {{\'A}guas, H., Fortunato, E., Pereira, L., Silva, V., Martins, R.} } @article {Martins1999158, title = {Role of the resistive layer on the performances of 2D a-Si:H thin film position sensitive detectors}, journal = {Thin Solid Films}, volume = {337}, number = {1-2}, year = {1999}, note = {

cited By 18

}, pages = {158-162}, abstract = {

The aim of this work is to present an analytical model which can to interpret the role of the collecting resistive layer on the static performances exhibited by 2D amorphous silicon hydrogenated p-i-n thin film position sensitive detectors. In addition, experimental results concerning the device linearity and spatial resolution are presented and checked against the predicted values of the analytical model proposed. {\textcopyright} 1999 Elsevier Science S.A. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000320596\&partnerID=40\&md5=3d47090b75eba563c94ddd9a9ecfa70f}, author = {Martins, R.a b , Fortunato, E.a b} } @article {{\'A}guas2004183, title = {Role of the rf frequency on the structure and composition of polymorphous silicon films}, journal = {Journal of Non-Crystalline Solids}, volume = {338-340}, number = {1 SPEC. ISS.}, year = {2004}, note = {

cited By 1

}, pages = {183-187}, abstract = {

In this work we present results of structural composition and morphological characteristics of polymorphous silicon (pm-Si:H) films deposited by PECVD at 13.56 and 27.12 MHz. In addition, the role of the excitation frequency on the growth rate will be also analyzed. The results show that by using the 27.12 MHz excitation frequency the hydrogen dilution in the plasma needed to produce pm-Si:H can be reduced by more than 50\% as well as the rf power density, leading to an increase on the growth rate to values higher than 3 {\r A}/s. Spectroscopic ellipsometry and Raman spectroscopy show that the 27.12 MHz pm-Si:H films are more ordered than the pm-Si:H films produced at 13.56 MHz, while the infrared spectroscopy show that the SiH2 concentration in the films is strongly reduced. AFM measurements reveal that the films produced at 27.12 MHz films are more structured, presenting also higher roughness. {\textcopyright} 2004 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2004.02.049}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-2942588869\&partnerID=40\&md5=c93941b69091ccf87327d3ea6bdc63cc}, author = {{\'A}guas, H.a , Raniero, L.a , Pereira, L.a , Viana, A.S.b , Fortunato, E.a , Martins, R.a} } @article {Pimentel20061448, title = {Role of the thickness on the electrical and optical performances of undoped polycrystalline zinc oxide films used as UV detectors}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 6

}, pages = {1448-1452}, abstract = {

In this paper we present the effect of thickness on the electrical and optical properties of intrinsic/nondoped zinc oxide thin films deposited at room temperature by radio frequency magnetron sputtering, able to be used as a semiconductor material on electronic devices, like for example ozone gas sensors and ultraviolet detectors. These films are polycrystalline with a c-axis preferential orientation parallel to the substrate. The films present a resistivity that varies from 5.0 {\texttimes} 104 Ω cm to 1.0 {\texttimes} 109 Ω cm with an optical visible transmittance of 85\%. The sensor response exceeds more than five orders of magnitude when exposed to UV light recovering to the initial state in the presence of ozone. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2006.02.022}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33745470865\&partnerID=40\&md5=6faafaadec1a6452643e3782861a6aec}, author = {Pimentel, A.C., Gon{\c c}alves, A., Marques, A., Martins, R., Fortunato, E.} } @article {{\'A}guas20102547, title = {Role of trimethylboron to silane ratio on the properties of p-type nanocrystalline silicon thin film deposited by radio frequency plasma enhanced chemical vapour deposition}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {10}, number = {4}, year = {2010}, note = {

cited By 3

}, pages = {2547-2551}, abstract = {

Trimethylboron (TMB) has been receiving attention as a valid alternative to diborane and methane mixtures for the deposition of p-type silicon films for applications in optoelectronic devices such as solar cells. In this paper we report on p-type hydrogenated nanocrystalline silicon carbide (nc-Si:C:H) films produced by standard 13.56 MHz plasma enhanced chemical vapour deposition technique, using TMB as gas source, under high hydrogen dilution (98\%) and using high deposition pressures (3 Torr). The films obtained were characterized by spectroscopic ellipsometry (SE), Raman spectroscopy (RS), and electrical measurements to determine their optical, structural and electrical properties. We achieved conductivities as high as 8.3 (Ω cm) -1, one of the highest values of conductivity published to date using TMB with standard rf-PECVD. Spectroscopic ellipsometry modeling revealed that the films growth mechanism proceeds through a sub-surface layer mechanism that leads to the formation of nanocrystalline silicon. Copyright {\textcopyright} 2010 American Scientific Publishers All rights reserved.

}, doi = {10.1166/jnn.2010.1434}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77954980837\&partnerID=40\&md5=af5335b2536fe611fc75bb38dbdb34d3}, author = {{\'A}guas, H.a b , Filonovich, S.A.a , Bernacka-Wojcik, I.b , Fortunato, E.a , Martins, R.a b} } @article {Martins2005135, title = {Room temperature dc and ac electrical behaviour of undoped ZnO films under UV light}, journal = {Materials Science and Engineering B: Solid-State Materials for Advanced Technology}, volume = {118}, number = {1-3}, year = {2005}, note = {

cited By 14

}, pages = {135-140}, abstract = {

This paper studies the dc and ac impedance behaviour of undoped ZnO thin films produced by spray pyrolysis and rf magnetron sputtering under UV light illumination, at room temperature, emphasising the role that the crystallite size, structure, surface morphology and the state of surface have on the electrical responsivities obtained. The results achieved show that the sputtered films with crystal sizes of about 4 nm exhibit dc electrical UV responsivities of 108. On the other hand, the spray pyrolysis films exhibit the lowest dc responsivities, due the high crystal sizes and state of surface contamination, to which very good capacitance responses were obtained, mainly due to the degree of porosity exhibit by these films when produced at low temperatures. Based on that, a two-phase electrical model is proposed to explain the set of behaviours observed. {\textcopyright} 2005 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.mseb.2004.12.089}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-15344347211\&partnerID=40\&md5=669b234334873e308248e83aca1baebb}, author = {Martins, R., Igreja, R., Ferreira, I., Marques, A., Pimentel, A., Gon{\c c}alves, A., Fortunato, E.} } @article {Pei2009, title = {Room-temperature cosputtered HfO2 - Al2 O3 multicomponent gate dielectrics}, journal = {Electrochemical and Solid-State Letters}, volume = {12}, number = {10}, year = {2009}, note = {

cited By 15

}, pages = {G65-G68}, abstract = {

Hafnium oxide-aluminum oxide (HfAlO) dielectric films were cosputtered using HfO2 and Al2 O3 targets, and their properties are studied in comparison with pure HfO2 films. The X-ray diffraction studies confirmed that the HfO2 films are nanocrystalline with a monoclinic phase. The as-deposited HfAlO films with a chemical composition of (HfO2) 0.86 (Al2 O3) 0.14 are amorphous even after annealing at 500{\textdegree}C. Further, the cosputtered films show a slight reduction in leakage current. The leakage current density may be significantly reduced below 3{\texttimes} 10-10 A cm-2 at an electric field of 0.25 MV/cm when applying the proper radio-frequency bias to the substrate. {\textcopyright} 2009 The Electrochemical Society.

}, doi = {10.1149/1.3186643}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-68949163562\&partnerID=40\&md5=ff269fe01cc97fe08929f33f7c7e9d29}, author = {Pei, Z.L.a , Pereira, L.a , Gonalves, G.a , Barquinha, P.a , Franco, N.b , Alves, E.b , Rego, A.M.B.c , Martins, R.a , Fortunato} } @article {Martins2009308, title = {Selective floating gate non-volatile paper memory transistor}, journal = {Physica Status Solidi - Rapid Research Letters}, volume = {3}, number = {9}, year = {2009}, note = {

cited By 18

}, pages = {308-310}, abstract = {

Here we report the performance of a selective floating gate (V GS) n-type non-volatile memory paper field-effect transistor. The paper dielectric exhibits a spontaneous polarization of about 1 mCm-2 and GIZO and IZO amorphous oxides are used respectively as the channel and the gate layers. The drain and source regions are based in continuous conductive thin films that promote the integration of fibres coated with the active semiconductor. The floating memory transistor writes, reads and erases the stored information with retention times above 14500 h, and is selective (for VGS \> 5 {\textpm} 0.1 V). That is, to erase stored information a symmetric pulse to the one used to write must be utilized, allowing to store in the same space different information. {\textcopyright} 2009 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/pssr.200903268}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-73949092995\&partnerID=40\&md5=d088f25c8d03adf11ca177f3be290acf}, author = {Martins, R., Barquinha, P., Pereira, L., Correia, N., Gon{\c c}alves, G., Ferreira, I., Fortunato, E.} } @article {Malik1998333, title = {Selective optical sensors from 0.25 to 1.1 μm based on metal oxide-semiconductor heterojunctions}, journal = {Sensors and Actuators, A: Physical}, volume = {68}, number = {1-3}, year = {1998}, note = {

cited By 2

}, pages = {333-337}, abstract = {

We present a set of high-efficiency optical sensors for the spectral range from 0.25 to 1.1 μm based on metal oxide-semiconductor heterostructures using different substrates: GaP, GaSe, AlxGa1 - xAs, GaAs and Si. A set of several transparent conductive metal oxide films such as indium, tin and zinc oxides fabricated by the spray pyrolysis method and its doping procedure has been investigated. The results show that heavily doped indium and tin oxide films are preferable as the active transparent conductive electrode in heterojunction surface-barrier structures. The fabricated sensors exhibit several features such as process simplicity, high quantum efficiency, uniformity of sensitivity over the active area and a high response speed. Such sensors can be used for precision measurements in different scientific and technical applications. {\textcopyright} 1998 Elsevier Science S.A. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0041636166\&partnerID=40\&md5=a7bb9b1879a438951598073743fc0f69}, author = {Malik, A.a , S{\^e}co, A.b , Fortunato, E.c , Martins, R.c} } @article {Malik1998333, title = {Selective optical sensors from 0.25 to 1.1 μm based on metal oxide-semiconductor heterojunctions}, journal = {Sensors and Actuators, A: Physical}, volume = {68}, number = {1 -3 pt 2}, year = {1998}, note = {

cited By 1

}, pages = {333-337}, abstract = {

We present a set of high-efficiency optical sensors for the spectral range from 0.25 to 1.1 μm based on metal oxide-semiconductor heterostructures using different substrates: GaP, GaSe, AlxGa1-xAs, GaAs and Si. A set of several transparent conductive metal oxide films such as indium, tin and zinc oxides fabricated by the spray pyrolysis method and its doping procedure has been investigated. The results show that heavily doped indium and tin oxide films are preferable as the active transparent conductive electrode in heterojunction surface-barrier structures. The fabricated sensors exhibit several features such as process simplicity, high quantum efficiency, uniformity of sensitivity over the active area and a high response speed. Such sensors can be used for precision measurements in different scientific and technical applications.

}, doi = {10.1016/S0924-4247(98)00035-1}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032097777\&partnerID=40\&md5=2f5873dd1b0115ffbf0d5243a04a02b8}, author = {Malik, Alexander, Seco, Ana, Fortunato, Elvira, Martins, Rodrigo} } @article {Ferreira2010332, title = {Self-rechargeable paper thin-film batteries: Performance and applications}, journal = {IEEE/OSA Journal of Display Technology}, volume = {6}, number = {8}, year = {2010}, note = {

cited By 20

}, pages = {332-335}, abstract = {

This paper reports on the use of cellulose paper simultaneously as electrolyte, separation of electrodes, and physical support of a rechargeable battery. The deposition on both faces of a paper sheet of metal or metal oxides thin layers with different electrochemical potentials, respectively as anode and cathode, such as Cu and Al, lead to an output voltage of 0.70 V and a current density that varies between 150 nA/cm2 and 0.5 mA/cm2, subject to the paper composition, thickness and the degree of OHx species adsorbed in the paper matrix. The electrical output of the paper battery is independent of the electrodes thickness but strongly depends on the atmospheric relative humidity (RH), with a current density enhancement by more than 3 orders of magnitude when RH changes from 60\% to 85\%. Besides flexibility, low cost, low material consumption, environmental friendly, the power output of paper batteries can be adapted to the desired voltagecurrent needed, by proper integration. A 3-V prototype was fabricated to control the ON/OFF state of a paper transistor. {\textcopyright} 2006 IEEE.

}, doi = {10.1109/JDT.2010.2056672}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955610885\&partnerID=40\&md5=48450478673e187c3ba17546c987abf0}, author = {Ferreira, I., Br{\'a}s, B., Correia, N., Barquinha, P., Fortunato, E., Martins, R.} } @article {Malik1998359, title = {Silicon active optical sensors: From functional photodetectors to smart sensors}, journal = {Sensors and Actuators, A: Physical}, volume = {68}, number = {1-3}, year = {1998}, note = {

cited By 1

}, pages = {359-364}, abstract = {

We have developed new types of functional and smart optical silicon sensors, based on ITO/multichannel insulator/silicon structures, which are able to execute electronic functions such as amplifying the photocurrent (without avalanche multiplication), transforming the input optical signal into a radio frequency output signal and transforming the analogue input optical signal to a digital output form, without external active electronic components. These new functional optical sensors allow a substantial simplification of the registration of optical signals as well as of the electronic scheme to be used. {\textcopyright} 1998 Elsevier Science S.A. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0042638115\&partnerID=40\&md5=9927513cbc9d4e139a4930fe9e87a946}, author = {Malik, A., Martins, R.} } @article {Malik1998359, title = {Silicon active optical sensors: from functional photodetectors to smart sensors}, journal = {Sensors and Actuators, A: Physical}, volume = {68}, number = {1 -3 pt 2}, year = {1998}, note = {

cited By 2

}, pages = {359-364}, abstract = {

We have developed new types of functional and smart optical silicon sensors, based on ITO/multichannel insulator/silicon structures, which are able to execute electronic functions such as amplifying the photocurrent (without avalanche multiplication), transforming the input optical signal into a radio frequency output signal and transforming the analogue input optical signal to a digital output form, without external active electronic components. These new functional optical sensors allow as substantial simplification of the registration of optical signals as well as of the electronic scheme to be used.

}, doi = {10.1016/S0924-4247(98)00068-5}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032098016\&partnerID=40\&md5=f87c4cd64f52a7dbc1f96d110197b0f5}, author = {Malik, Alexander, Martins, Rodrigo} } @article {Ferreira20018, title = {Silicon carbide alloys produced by hot wire, hot wire plasma-assisted and plasma-enhanced CVD techniques}, journal = {Applied Surface Science}, volume = {184}, number = {1-4}, year = {2001}, note = {

cited By 14

}, pages = {8-19}, abstract = {

In this work, we report the optical and compositional properties of hydrogenated amorphous silicon carbide (a-SiC:H) thin films produced by plasma-enhanced chemical vapor deposition (PE-CVD), hot wire CVD (HW-CVD) and hot wire plasma-assisted CVD (HWPA-CVD) processes. The optical band gap of a-SiC:H films was controlled from 1.85 to 3.5 eV by varying the percentage of ethylene in the silane gas mixture from 3 to 100\%. Adding a rf plasma to the hot wire process the carbon gas source dissociation is implemented leading to an increase in bulk carbon incorporation. This evidence is proved by the enhancement of the peak ascribed to the SiC stretching vibration mode, the reduction of the peak related to the SiH wagging modes, the decrease in the refractive index and the increase of optical band gap. The influence of hydrogen gas dilution on the properties of the films obtained by the different methods is also reported. {\textcopyright} 2001 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0169-4332(01)00663-8}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035852240\&partnerID=40\&md5=78e05151413ab58ebfc057fce5715bff}, author = {Ferreira, I.a , Costa, M.E.V.b , Pereira, L.a , Fortunato, E.a , Martins, R.a , Ramos, A.R.c , Silva, M.F.c} } @article {Cabrita2001437, title = {Silicon carbide photodiodes: Schottky and PINIP structures}, journal = {Applied Surface Science}, volume = {184}, number = {1-4}, year = {2001}, note = {

cited By 5

}, pages = {437-442}, abstract = {

This work deals with the study of the role of intra-gap density of states and films composition on the colour selection of the collection spectrum of glass/ITO/a-Six:C1-x:H/Al Schottky photodiodes produced in a conventional plasma-enhanced chemical vapour deposition (PECVD) system using as gas sources silane and a controlled mixtures of silane and methane. To do so, properties of the films were investigated, especially the one concerning the determination of the valence controllability of the films produced and the density of bulk states. Besides that, a PINIP device was also produced, using the a-Six:C1-x:layer that lead to the best Schottky diode performances. {\textcopyright} 2001 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0169-4332(01)00531-1}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035852235\&partnerID=40\&md5=e0f9c6ef8da20d190f429a9bbae54470}, author = {Cabrita, A., Pereira, L., Brida, D., Lopes, A., Marques, A., Ferreira, I., Fortunato, E., Martins, R.} } @article {Silva2004120, title = {Silicon etching in CF4/O2 and SF6 atmospheres}, journal = {Materials Science Forum}, volume = {455-456}, year = {2004}, note = {

cited By 2

}, pages = {120-123}, abstract = {

The aim of this work is to present a process able to allow a fast method to clean plasma enhanced chemical vapour deposition (PECVD) systems used to produce amorphous silicon films and their alloys, and a proper device patterning when required. In this work we propose to study CF4/O2 or SF6 as etchant gases at room temperature to perform cleaning and films patterning. The aim is to select the process that leads to a faster cleaning process without formation of residual contaminants or to anisotropic patterning of very thin layers. The influence of some plasma parameters, such as pressure (p), power (P) and flow (f) for the etchant gases used will be also analysed.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17144451306\&partnerID=40\&md5=96ca2169250b0db030a416759c85ae10}, author = {Silva, A., Raniero, L., Ferreira, E., {\'A}guas, H., Pereira, L., Fortunato, E., Martins, R.} } @article {Martins200121, title = {Silicon films produced by PECVD under powder formation conditions}, journal = {Materials Science Forum}, volume = {382}, year = {2001}, note = {

cited By 0

}, pages = {21-28}, abstract = {

The process conditions of growing thin silicon films by plasma enhanced chemical vapour deposition (PECVD) were presented. The plasma impedance was found to monitor the powders in the PECVD systems and good quality silicon films were grown close to the plasma regime where the powders were formed. The silicon films exhibited properties which were interpreted based on a two-phase model where silicon nanostructures were embedded in a disordered network.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035689049\&partnerID=40\&md5=18fffe34e1537e6bd368da111f6932da}, author = {Martins, R., {\'A}guas, H., Silva, V., Ferreira, I., Cabrita, A., Fortunato, E.} } @article {Martins2002219, title = {Silicon nanostructure thin film materials}, journal = {Vacuum}, volume = {64}, number = {3-4}, year = {2002}, note = {

cited By 2

}, pages = {219-226}, abstract = {

This paper deals with the growth process of nanostructured silicon films produced by chemical vapour deposition technique, at or close to the γ-regime where powders are formed. There, besides the set of chemical reactions undertaken by the species decomposed on the growth surface, the importance of the physics of the plasma in managing the powders and on the final film performances will be shown. To identify the plasma region where Si nanoaggregates are formed, we propose the use of a new parameter that translates the energy coupling of the rf power to the species of the gas flow, per pressure range of the process. By doing so we could establish an excellent correlation between this ratio and the plasma parameters such as peak to peak rf voltage and plasma impedance, or with the films defect density and their transport properties. Apart from that, we also show that high compact Si nanoclusters could be grown under moderate ion bombardment. Finally, to allow the growth at high rates of controlled silicon nanostructures, a three cycling process based on hot wire chemical vapour deposition and plasma assisting the hot wire technique will be discussed. {\textcopyright} 2002 Elsevier Science Ltd. All rights reserved.

}, doi = {10.1016/S0042-207X(01)00339-6}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-8444248193\&partnerID=40\&md5=a24b10de9fdcab00d623c7ed69840533}, author = {Martins, R., {\'A}guas, H., Silva, V., Ferreira, I., Cabrita, A., Fortunato, E.} } @article {{\'A}guas20114620, title = {Silicon thin film solar cells on commercial tiles}, journal = {Energy and Environmental Science}, volume = {4}, number = {11}, year = {2011}, note = {

cited By 35

}, pages = {4620-4632}, abstract = {

Nanostructured silicon single junction thin film solar cells were deposited on commercial red clay roof tiles with engobe surfaces and earthenware wall tiles with glazed surfaces, with a test area of 24 mm 2. We studied the influence of the type of substrate tile, back contact, buffer layer and SiO x passivation layer on the optoelectronic performance of the solar cells. Despite the fact that typical micrometre-sized defects on the surfaces of the tiles and the porous nature of the ceramic substrates make deposition of homogeneous thin films on them quite challenging, we have been able to achieve a cell efficiency of 5\% and a quantum efficiency of 80\% on non-fully optimized cells on commercial tiles. The method is industrially employable utilizing pre-existing plasma-enhanced chemical vapour deposition technologies. The cost-effectiveness and industrial feasibility of the technique are discussed. Our study shows that photovoltaic tiles can combine energy generation with architectural aesthetics leading to significant implications for advancement in building integrated photovoltaics. {\textcopyright} 2011 The Royal Society of Chemistry.

}, doi = {10.1039/c1ee02303a}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-80055063571\&partnerID=40\&md5=25991e3f08ca3f29f63bbba6d275b2d0}, author = {{\'A}guas, H., Ram, S.K., Ara{\'u}jo, A., Gaspar, D., Vicente, A., Filonovich, S.A., Fortunato, E., Martins, R., Ferreira, I.} } @article {Zhang20063001, title = {Silicon thin films prepared in the transition region and their use in solar cells}, journal = {Solar Energy Materials and Solar Cells}, volume = {90}, number = {18-19}, year = {2006}, note = {

cited By 17

}, pages = {3001-3008}, abstract = {

Diphasic silicon films (nc-Si/a-Si:H) have been prepared by a new regime of plasma enhanced chemical vapour deposition in the region adjacent of phase transition from amorphous to microcrystalline state. Comparing to the conventional amorphous silicon (a-Si:H), the nc-Si/a-Si:H has higher photoconductivity (σph), better stability, and a broader light spectral response range in the longer wavelength range. It can be found from Raman spectra that there is a notable improvement in the medium range order. The blue shift for the stretching mode and red shift for the wagging mode in the IR spectra also show the variation of the microstructure. By using this kind of film as intrinsic layer, a p-i-n junction solar cell was prepared with the initial efficiency of 8.51\% and a stabilized efficiency of 8.01\% (AM1.5, 100 mw/cm2) at room temperature. {\textcopyright} 2006.

}, doi = {10.1016/j.solmat.2006.06.006}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33748460114\&partnerID=40\&md5=e460851dd99637e129bb518a324cabe0}, author = {Zhang, S.a b , Liao, X.b , Raniero, L.a , Fortunato, E.a , Xu, Y.b , Kong, G.b , {\'A}guas, H.a , Ferreira, I.a , Martins, R.a} } @article {Contreras201529938, title = {Simulated and real sheet-of-light 3D object scanning using a-Si: H thin film PSD arrays}, journal = {Sensors (Switzerland)}, volume = {15}, number = {12}, year = {2015}, note = {

cited By 0

}, pages = {29938-29949}, abstract = {

AMATLAB/SIMULINK software simulation model (structure and component blocks) has been constructed in order to view and analyze the potential of the PSD (Position Sensitive Detector) array concept technology before it is further expanded or developed. This simulation allows changing most of its parameters, such as the number of elements in the PSD array, the direction of vision, the viewing/scanning angle, the object rotation, translation, sample/scan/simulation time, etc. In addition, results show for the first time the possibility of scanning an object in 3D when using an a-Si:H thin film 128 PSD array sensor and hardware/software system. Moreover, this sensor technology is able to perform these scans and render 3D objects at high speeds and high resolutions when using a sheet-of-light laser within a triangulation platform. As shown by the simulation, a substantial enhancement in 3D object profile image quality and realism can be achieved by increasing the number of elements of the PSD array sensor as well as by achieving an optimal position response from the sensor since clearly the definition of the 3D object profile depends on the correct and accurate position response of each detector as well as on the size of the PSD array. {\textcopyright} 2015 by the authors; licensee MDPI, Basel, Switzerland.

}, doi = {10.3390/s151229779}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949008497\&partnerID=40\&md5=cb7ee4e14e445e49b0cc18f493cb3d6d}, author = {Contreras, J.a , Tornero, J.a , Ferreira, I.b , Martins, R.b , Gomes, L.c , Fortunato, E.b} } @article {Fantoni1999381, title = {Simulation of hydrogenated amorphous and microcrystalline silicon optoelectronic devices}, journal = {Mathematics and Computers in Simulation}, volume = {49}, number = {4-5}, year = {1999}, note = {

cited By 47

}, pages = {381-401}, abstract = {

This paper is concerned with the modelling and simulation of amorphous and microcrystalline silicon optoelectronic devices. The physical model and its mathematical formulation are extensively described. Its numerical reduction is also discussed together with the presentation of a computer program dedicated to the simulation of the electrical behaviour of such devices. This computer program, called ASCA (Amorphous Silicon Solar Cells Analysis), is capable of simulating, on one- and two-dimensional domains, the internal electrical behaviour of multi-layer structures, homojunctions and heterojunctions under simple or complex spectra illumination and externally applied biases. The applications of the simulator presented in this work are the analysis of μc/a-Si:H p-i-n photovoltaic cell in thermal equilibrium and illuminated by monochromatic light and the AMI.5 solar spectrum, with and without polarisation. We also study the appearance within the device of lateral components of the electric field and current density vectors when the illumination is not uniform. {\textcopyright} 1999 IMACS/Elsevier Science B.V. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0346156099\&partnerID=40\&md5=79f60684be0b8fd9b2f8d1b48c91969f}, author = {Fantoni, A.a , Vieira, M.b , Martins, R.a} } @article {Neves2012204, title = {Sintering behavior of nano- and micro-sized ZnO powder targets for rf magnetron sputtering applications}, journal = {Journal of the American Ceramic Society}, volume = {95}, number = {1}, year = {2012}, note = {

cited By 14

}, pages = {204-210}, abstract = {

In this work, the nonisothermal sintering behavior of as-received commercial high purity ZnO micrometric (m-ZnO), submicrometric (sm-ZnO) and nanometric (n-ZnO) powders was studied. The sintering behavior for sputtering target production was evaluated by changing the green density of samples from 62\% of theoretical density (TD) to 35\%. We observed that for n-ZnO powder, the maximum shrinkage rate (MSR) temperature (T MSR) was not affected by the green density, and that it was reached at lower temperatures (\~{}710{\textdegree}C) compared with m-ZnO and sm-ZnO powders. For these powders, the temperature of MSR increased from 803{\textdegree}C to 934{\textdegree}C and from 719{\textdegree}C to 803{\textdegree}C as TD changed from 62\% to 35\% TD, respectively. Small grain size (\~{}0.560 μm) and high density targets were obtained for n-ZnO when sintered at temperatures below the T MSR. Heating rate from 1{\textdegree}C to 15{\textdegree}C/min led to lower activation energy for n-ZnO (\~{}201 {\textpm} 3 kJ/mol) than for the submicrometric (sm-ZnO) (\~{}332 {\textpm} 20 kJ/mol) and micrometric (m-ZnO) (\~{}273 {\textpm} 9 kJ/mol) powders. Using the model proposed by Bannister and Woolfrey, an n value of 0.75 was found, which was correlated with a combination of viscous flow and volume diffusion mechanisms that should control the initial stage of n-ZnO sintering. No significant differences were observed for n-ZnO powder in terms of density when the size of targets (scale-up effect) was increased, while in the case of m-ZnO and sm-ZnO, a delay in the densification was observed, which was related to the higher sinterability of n-ZnO powder. Two inches ZnO ceramic targets with different particle sizes and final densities were used in an rf magnetron sputtering system to produce ZnO films under the same deposition conditions. Films with thickness around 100 nm and good uniformity were produced using those targets, and no variation was observed in the optical and morphological properties. However, low electrical resistivity (1.4 Omega;{\textperiodcentered}cm) films were obtained with n-ZnO targets, which could be explained in terms of a nonstoichiometric Zn:O composition of the started powders. {\textcopyright} 2011 The American Ceramic Society.

}, doi = {10.1111/j.1551-2916.2011.04874.x}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84855354511\&partnerID=40\&md5=2890599511310a79642ad1fe29a7277d}, author = {Neves, N.a b , Barros, R.a b , Antunes, E.a , Ferreira, I.b , Calado, J.a , Fortunato, E.b , Martins, R.b} } @article {Vicente201513226, title = {Solar cells for self-sustainable intelligent packaging}, journal = {Journal of Materials Chemistry A}, volume = {3}, number = {25}, year = {2015}, note = {

cited By 3

}, pages = {13226-13236}, abstract = {

Nowadays there is a strong demand for intelligent packaging to provide comfort, welfare and security to owners, vendors and consumers by allowing them to know the contents and interact with the goods. This is of particular relevance for low cost, fully disposable and recyclable products, such as identification tags and medical diagnostic tests, and devices for analysis and/or quality control in food and pharmaceutical industries. However, the increase of complexity and processing capacity requires continuous power and can be addressed by the combined use of a small disposable battery, charged by a disposable solar cell, which is able to work under indoor lighting. Herein, we show a proof-of-concept of the pioneering production of thin-film amorphous silicon (a-Si:H) solar cells with an efficiency of 4\% by plasma enhanced chemical vapour deposition (PECVD) on liquid packaging cardboard (LPC), which is commonly used in the food and beverage industries. Such accomplishment put us one step closer to this revolution by providing a flexible, renewable and extremely cheap autonomous energy packaging system. Moreover, such Si thin films take advantage of their good performance at low-light levels, which also makes them highly desirable for cheap mobile indoor applications. {\textcopyright} The Royal Society of Chemistry.

}, doi = {10.1039/c5ta01752a}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84934898328\&partnerID=40\&md5=d75c88a2279ce4111a533cdf7fa52300}, author = {Vicente, A.a , {\'A}guas, H.a , Mateus, T.a , Ara{\'u}jo, A.a , Lyubchyk, A.a , Siitonen, S.b , Fortunato, E.a , Martins, R.a} } @article {Grey2016, title = {Solid State Electrochemical WO3 Transistors with High Current Modulation}, journal = {Advanced Electronic Materials}, volume = {2}, number = {9}, year = {2016}, note = {

cited By 0

}, abstract = {

In this paper, the role of electrode architecture (conventional and interdigital), device structure (vertical or planar), and tungsten oxide (WO3) channel thickness on the electro-optical performances of room temperature sputtered electrochromic transistors (EC-Ts) is reported. A larger number of electro-reducible tungsten sites in thicker WO3 films provide improved optical density and coloration efficiency. However, overall transistor performance is found to suffer in planar EC-Ts with the conventional electrode architecture, where the step to planar interdigital electrodes leaves the devices to be almost insensitive to WO3 thickness. Vertical structures result in improved device properties and stability, given to the shorter distance between gate electrode and semiconductor and to the encapsulation effect provided by such structures. These devices show an On{\textendash}Off ratio of 5 {\texttimes} 106 and a transconductance (g m) of 3.59 mS, for gate voltages (V G) between -2 and 2 V, which to the authors{\textquoteright} knowledge are the best values ever reported for electrochemical transistors. The simple and low-cost processing together with the electrical/optical performances well supported into a comprehensive analysis of device physics opens doors for a wide range of new applications in display technologies, biosensors, fuel cells, or electrochemical logic circuits. {\textcopyright} 2016 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim

}, doi = {10.1002/aelm.201500414}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987719072\&partnerID=40\&md5=440ccb8b52c18ce3a47d246638880577}, author = {Grey, P., Pereira, L., Pereira, S., Barquinha, P., Cunha, I., Martins, R., Fortunato, E.} } @article {Ferreira20111099, title = {Solid-state paper batteries for controlling paper transistors}, journal = {Electrochimica Acta}, volume = {56}, number = {3}, year = {2011}, note = {

cited By 13

}, pages = {1099-1105}, abstract = {

A commercial sheet of paper based on natural cellulose fibers acting as permeable membrane with thin film metal cathode (Cu) and anode (Al) layers in each face was used to produce paper batteries that could be interconnected in series and rechargeable using water as electrolyte. Their electrical characteristics and the set of electrochemical reactions that support the experimental behavior observed are described in this paper. A series of integrated batteries able to supply a voltage of about 3 V and a current ranging from 0.7 μA to 25 μA in cells with sizes of 1.2 cm {\texttimes} 3.0 cm for a relative humidity in the range of 50-65\% were produced in a single sheet of paper, and successfully applied to control the ON/OFF gate state of paper transistors. {\textcopyright} 2010 Elsevier Ltd. All rights reserved.

}, doi = {10.1016/j.electacta.2010.10.018}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-78650517602\&partnerID=40\&md5=aa4fb219b54cf44c931ec6f13392fb68}, author = {Ferreira, I.a , Br{\'a}s, B.a , Martins, J.I.b , Correia, N.a , Barquinha, P.a , Fortunato, E.a , Martins, R.a} } @article {Liu2016, title = {Solution-Processed Alkaline Lithium Oxide Dielectrics for Applications in n- and p-Type Thin-Film Transistors}, journal = {Advanced Electronic Materials}, volume = {2}, number = {9}, year = {2016}, note = {

cited By 0

}, abstract = {

High-k alkaline lithium oxide (LiOx) thin films are fabricated by spin-coating method. The LiOx thin films are annealed at different temperatures and characterized by various techniques. An optimized LiOx dielectric is achieved at an annealing temperature of 300 {\textdegree}C and exhibits wide bandgap of ≈5.5 eV, smooth surface, relatively permittivity of ≈6.7, and low leakage current density. The as-fabricated LiOx thin films are integrated, as gate dielectrics, in both n-channel indium oxide (In2O3) and p-channel cupric oxide (CuO) transistors. The optimized In2O3/LiOx thin-film transistor (TFT) exhibits high performance and high stability, such as Ion/Ioff of 107, electron mobility of 5.69 cm2 V-1 s-1, subthreshold swing of 70 mV dec-1, negligible hysteresis, and threshold voltage shift of 0.1 V under bias stress for 1.5 h. Meanwhile, the p-channel CuO TFT based on LiOx dielectric shows high Ion/Ioff of 105 and hole mobility of 1.72 cm2 V-1 s-1. All the electrical performances are achieved at an ultra-low operating voltage of 2 V. Considering the simple procedure, the moderate annealing temperature, and the low power consumption merits, these outstanding characteristics represent a significant advance toward the development of battery compatible and portable electronics. {\textcopyright} 2016 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim

}, doi = {10.1002/aelm.201600140}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978872985\&partnerID=40\&md5=4aa037be9fb7e08f7c4b9f1de20ecc93}, author = {Liu, A.a b c , Liu, G.a b c , Zhu, C.a b c , Zhu, H.a b c , Fortunato, E.d , Martins, R.d , Shan, F.a b c} } @article {Jiang2016, title = {Solution-processed high-k magnesium oxide dielectrics for low-voltage oxide thin-film transistors}, journal = {Applied Physics Letters}, volume = {109}, number = {18}, year = {2016}, note = {

cited By 0

}, abstract = {

Solution-processed metal-oxide thin films with high dielectric constants (k) have been extensively studied for low-cost and high-performance thin-film transistors (TFTs). In this report, MgO dielectric films were fabricated using the spin-coating method. The MgO dielectric films annealed at various temperatures (300, 400, 500, and 600 {\textdegree}C) were characterized by using thermogravimetric analysis, optical spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and atomic-force microscopy. The electrical measurements indicate that the insulating properties of MgO thin films are improved with an increase in annealing temperature. In order to clarify the potential application of MgO thin films as gate dielectrics in TFTs, solution-derived In2O3 channel layers were separately fabricated on various MgO dielectric layers. The optimized In2O3/MgO TFT exhibited an electron mobility of 5.48 cm2/V s, an on/off current ratio of 107, and a subthreshold swing of 0.33 V/dec at a low operation voltage of 6 V. This work represents a great step toward the development of portable and low-power consumption electronics. {\textcopyright} 2016 Author(s).

}, doi = {10.1063/1.4966897}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994337318\&partnerID=40\&md5=ce830c0cac38dd9b895cbc3873ea8bf0}, author = {Jiang, G.a b c , Liu, A.a b c , Liu, G.a b c , Zhu, C.a b c , Meng, Y.a b c , Shin, B.d , Fortunato, E.e , Martins, R.e , Shan,} } @article {Santos2015638, title = {Solvothermal synthesis of gallium-indium-zinc-oxide nanoparticles for electrolyte-gated transistors}, journal = {ACS Applied Materials and Interfaces}, volume = {7}, number = {1}, year = {2015}, note = {

cited By 5

}, pages = {638-646}, abstract = {

Solution-processed field-effect transistors are strategic building blocks when considering low-cost sustainable flexible electronics. Nevertheless, some challenges (e.g., processing temperature, reliability, reproducibility in large areas, and cost effectiveness) are requirements that must be surpassed in order to achieve high-performance transistors. The present work reports electrolyte-gated transistors using as channel layer gallium-indium-zinc-oxide nanoparticles produced by solvothermal synthesis combined with a solid-state electrolyte based on aqueous dispersions of vinyl acetate stabilized with cellulose derivatives, acrylic acid ester in styrene and lithium perchlorate. The devices fabricated using this approach display a ION/IOFF up to 1 {\texttimes} 106, threshold voltage (VTh) of 0.3-1.9 V, and mobility up to 1 cm2/(V s), as a function of gallium-indium-zinc-oxide ink formulation and two different annealing temperatures. These results validates the usage of electrolyte-gated transistors as a viable and promising alternative for nanoparticle based semiconductor devices as the electrolyte improves the interface and promotes a more efficient step coverage of the channel layer, reducing the operating voltage when compared with conventional dielectrics gating. Moreover, it is shown that by controlling the applied gate potential, the operation mechanism of the electrolyte-gated transistors can be modified from electric double layer to electrochemical doping. {\textcopyright} 2014 American Chemical Society.

}, doi = {10.1021/am506814t}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84921313308\&partnerID=40\&md5=31f1fc2e89db74f2e5dc5bc01d68692c}, author = {Santos, L., Nunes, D., Calmeiro, T., Branquinho, R., Salgueiro, D., Barquinha, P., Pereira, L., Martins, R., Fortunato, E.} } @article {Elangovan20081359, title = {Some studies on highly transparent wide band gap indium molybdenum oxide thin films rf sputtered at room temperature}, journal = {Thin Solid Films}, volume = {516}, number = {7}, year = {2008}, note = {

cited By 14

}, pages = {1359-1364}, abstract = {

Transparent wide band gap indium molybdenum oxide (IMO) thin films were rf sputtered on glass substrates at room temperature. The films were studied as a function of sputtering power (ranging 40-180~W) and sputtering time (ranging 2.5-20~min). The film thickness was varied in the range 50-400~nm. The as-deposited films were characterized by their structural (XRD), morphological (AFM), electrical (Hall Effect measurements) and optical (visible-NIR spectroscopy) properties. XRD studies revealed that the films are amorphous for the sputtering power <= 100~W and the deposition time <= 5~min, and the rest are polycrystalline with a strong reflection from (222) plane showing a preferential orientation. A minimum bulk resistivity of 2.65 {\texttimes} 10- 3~Ω cm and a maximum carrier concentration of 4.16 {\texttimes} 1020~cm- 3 are obtained for the crystalline films sputtered at 180~W (10~min). Whereas a maximum mobility (19.5 ~cm2 V- 1 s- 1) and average visible transmittance (\~{} 85\%) are obtained for the amorphous films sputtered at 80~W and 100~W respectively for 10~min. A minimum transmittance (\~{} 18\%) was obtained for the crystalline films sputtered at 180~W (\~{} 305~nm thick). The optical band gap was found varying between 3.75 and 3.90~eV for various sputtering parameters. The obtained results are analyzed and corroborated with the structure of the films. {\textcopyright} 2007 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2007.03.155}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-38649096325\&partnerID=40\&md5=08725280ed2e7fb8948e68116b9f80af}, author = {Elangovan, E.a , Marques, A.a , Viana, A.S.b , Martins, R.a , Fortunato, E.a} } @article {Fernandes20083410, title = {Spectral response characterization of a-Si:H-based MIS-type photosensors}, journal = {Physica Status Solidi (C) Current Topics in Solid State Physics}, volume = {5}, number = {10}, year = {2008}, note = {

cited By 1

}, pages = {3410-3413}, abstract = {

This paper reports on a method and a test setup developed to measure the transient dark current and the spectral response characteristics of a-Si:H MIS photosensors. Using this method the segmented-gate/SiNx/a Si:H/n +/ITO structures have been characterized under different biasing conditions. The dependences of the dark and light signals on the refresh pulse amplitude, offset voltage and pulse width were measured and analyzed. It is found that the amplitude of the time-dependent component of the leakage current associated with charge trapping at the insulator-semiconductor interface can be significantly reduced by adjusting the offset voltage. The observed bias dependence of the spectral response characteristics is explained by analyzing the charge carrier transport in the absorption layer at different wavelengths of the incident light. {\textcopyright} 2008 WILEY-VCH Verlag GmbH \& Co. KGaA.

}, doi = {10.1002/pssc.200778924}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77951181245\&partnerID=40\&md5=5a66e1cfb0b4a2db12a85a94df17bcad}, author = {Fernandes, M.a , Vygranenko, Y.a , Fantoni, A.a , Martins, R.b , Vieira, M.a} } @article {Raniero2004293, title = {Spectral response of large area amorphous silicon solar cells}, journal = {High Temperature Material Processes}, volume = {8}, number = {2}, year = {2004}, note = {

cited By 0

}, pages = {293-299}, abstract = {

In this work we report the study of spectral response on large area amorphous silicon solar cells (30{\texttimes}40 cm2), deposited through plasma enhanced chemical vapour deposition technique (PECVD) at excitation frequencies of 27.12MHz. To perform this work, the solar cells were split in units of area of 0.126 cm2, which allows determining the device homogeneity over all the entire solar cell. Emphasis of this work is put the role of thickness and optical band gap of p-doped layer on the collection efficiency, spectral response, current density-voltage curves under standard condition and spectroscopy impedance. The results show that high transparent p-doped layer can be deposited at 42mW/cm2, which allows increasing the collection efficiency in 45\%, at the blue region. The spectroscopy impedance performed showed to be efficient in analyzing the device shunt resistance, interfaces role on the device performances and the behaviour of the device depletion region, for the range of frequencies analysed.

}, doi = {10.1615/HighTempMatProc.v8.i2.130}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-22544467484\&partnerID=40\&md5=a4ef8ae106dcfffeb8720aa5d1e07f60}, author = {Raniero, L., Martins, N., Canhola, P., Pereira, S., Ferreira, I., Fortunato, E., Martins, R.} } @article {{\'A}guas2003345, title = {Spectroscopic ellipsometry study of amorphous silicon anodically oxidised}, journal = {Thin Solid Films}, volume = {427}, number = {1-2}, year = {2003}, note = {

cited By 8

}, pages = {345-349}, abstract = {

In this work, spectroscopic ellipsometry was used to characterise oxide films produced by anodic oxidation of amorphous silicon using an ethylene glycol (0.04 M KNO3) solution. The data obtained show that the growth of the oxide is not only a function of the voltage applied, but also of the current density and of the time process. An empiric model based on a power law is proposed for the growth of the oxide using, as parameters, the voltages and the time process. The oxide produced shows porosity of approximately 12\%, which can be reduced down to 6\% under well-controlled growth conditions. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0040-6090(02)01220-8}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037416725\&partnerID=40\&md5=6da64e396151535f91290e465055bb6f}, author = {{\'A}guas, H., Gon{\c c}alves, A., Pereira, L., Silva, R., Fortunato, E., Martins, R.} } @article {{\'A}guas2008880, title = {Spectroscopic ellipsometry study of Co-doped TiO 2 films}, journal = {Physica Status Solidi (A) Applications and Materials Science}, volume = {205}, number = {4}, year = {2008}, note = {

cited By 4

}, pages = {880-883}, abstract = {

Co-doped TiO 2 films were characterized by spectroscopic ellipsometry to determine their thickness, deposition rate and optical properties as function of substance temperature and background gas composition. To fit the data we used a combination of a single Tauc-Lorentz oscillator with the Drude free electron model to take in account the free electrons present in the film. The Co doping and addition of H 2 to the gas phase during film growth cause the formation of a titanium oxide which containsfree electrons that absorb the energy of the red part of the spectrum, causing k to increase. The n of the film at 1.5 eV is about 2.3 eV. The fittings also show that the n of films decreases and k increase at the surface. This can be related to a segregation of Co to the surface, which in some cases, of high substrate temperature and high H 2 flow during deposition, can lead to and even higher concentration of free electrons at the surface. {\textcopyright} 2008 WILEY-VCH Verlag GmbH \& Co. KGaA.

}, doi = {10.1002/pssa.200777843}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-54949141872\&partnerID=40\&md5=bfd6a3a0a043ba48c83fdb9ccbc0d678}, author = {{\'A}guas, H.a , Popovici, N.b , L Pereiraa , Conde, O.b , Branford, W.R.c , Cohen, L.F.c , Fortunato, E.a , Martins, R.a} } @article {Pereira20061204, title = {Spectroscopic ellipsometry study of nickel induced crystallization of a-Si}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 7

}, pages = {1204-1208}, abstract = {

The aim of this work is to present a spectroscopic ellipsometry study focused on the annealing time effect on nickel metal induced crystallization of amorphous silicon thin films. For this purpose silicon layers with 80 and 125 nm were used on the top of which a 0.5 nm Ni thick layer was deposited. The ellipsometry simulation using a Bruggemann Effective Medium Approximation shows that films with 80 nm reach a crystalline fraction of 72\% after 1 h annealing, appearing to be full crystallized after 2 h. No significant structural improvement is detected for longer annealing times. On the 125 nm samples the crystalline volume fraction after 1 h is only around 7\%, requiring 5 h to get a similar crystalline fraction than the one achieved with the thinner film. This means that the time required for full crystallization will be strongly determined by the Si layer thickness. Using a new fitting approach the Ni content within the films was also determined by SE and related to the silicon film thickness. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2006.02.018}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33745450387\&partnerID=40\&md5=3ada3b8a7e26fbad064de6800a3cad02}, author = {Pereira, L.a , {\'A}guas, H.a , Beckers, M.b , Martins, R.M.S.b , Fortunato, E.a , Martins, R.a} } @article {Parthiban2009, title = {Spray deposited molybdenum doped indium oxide thin films with high near infrared transparency and carrier mobility}, journal = {Applied Physics Letters}, volume = {94}, number = {21}, year = {2009}, note = {

cited By 18

}, abstract = {

Molybdenum doped (0-1 at. \%) indium oxide thin films with high near infrared (NIR) transparency and carrier mobility were deposited on Corning-1737 glass substrates at 400 {\textdegree}C by spray pyrolysis experimental technique. Films with mobility as high as \~{}149 cm2 /V s were obtained when annealed in vacuum at 550 {\textdegree}C, which also possess carrier concentration of \~{}1{\texttimes} 1020 cm-3 and resistivity as low as \~{}4.0{\texttimes} 10-4 cm. Further, both the average visible transmittance (500-800 nm) and the average NIR transmittance are \>83\%. This clearly shows that the transmittance is extended well into the NIR region. {\textcopyright} 2009 American Institute of Physics.

}, doi = {10.1063/1.3142424}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-66549084470\&partnerID=40\&md5=872d35754efd291fbe162af9da170a26}, author = {Parthiban, S.a , Ramamurthi, K.a , Elangovan, E.b , Martins, R.b , Fortunato, E.b} } @article {Pereira20092149, title = {Sputtered multicomponent amorphous dielectrics for transparent electronics}, journal = {Physica Status Solidi (A) Applications and Materials Science}, volume = {206}, number = {9}, year = {2009}, note = {

cited By 14

}, pages = {2149-2154}, abstract = {

In this work, we present the structural and electrical properties of HfO 2, HfO 2 +SiO 2, and HfO 2 +Al 2O 3 dielectric composite layers deposited by sputtering without any intentional substrate heating. The films were deposited on glass and 〈100〉 crystalline silicon (c-Si) substrates from ceramic targets by using argon (Ar) and oxygen (O 2) as sputtering and reactive gases, respectively. The incorporation of SiO 2 and Al 2O 3 into hafnia was obtained by co-sputtering and itwas controlled by adjusting the ratio of r.f. power applied between the targets. The HfO 2 films present a microcrystalline structure, when deposited at room temperature (RT). The lowest leakage current in c-Si MIS (Metal-Insulator- Semiconductor) structures (below 10 9A/cm 2 at 10V on films with a thickness around 180 nm) was obtained for an Ar/O 2 ratio of 14:1 sccm, and further increase in O 2 flow does not enhance the electrical characteristics. The codeposition of SiO 2 or Al 2O 3 with hafnia has a strong influence on the structure of the resulting films since they become amorphous. The leakage current in MISstructures incorporating these multi-component dielectrics is reduced at least by a factor of 2, which is accompanied by an increase on the band gap. The dielectric constant is decreased due to the lower values for SiO 2 and Al 2O 3. {\textcopyright} 2009 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/pssa.200881799}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-70349151333\&partnerID=40\&md5=b94a3dc15d7c2447577885c04eef5b8c}, author = {Pereira, L.a , Barquinha, P.a , Gon{\c c}alves, G.a , Vil{\`a}, A.b , Olziersky, A.b , Morante, J.b , Fortunato, E.a , Martins, R.a} } @article {Pereira200469, title = {Sputtering preparation of silicon nitride thin films for gate dielectric applications}, journal = {Materials Science Forum}, volume = {455-456}, year = {2004}, note = {

cited By 0

}, pages = {69-72}, abstract = {

Silicon nitride films were produced on glass and crystalline silicon substrates using r.f. magnetron sputtering to select the best process conditions (substrate temperature, gas pressure and r.f. power) to grow dielectrics for device applications such as low temperature thin film transistors, where special care has to be taken concerning the film{\textquoteright}s compactness and bulk defects. The films produced were analysed by different techniques such as ultra violet - visible - near infrared spectroscopy Fourier transformed infrared spectroscopy and capacitance measurements, aiming to correlate the films properties with its composition and degree of compactness. The role of the deposition pressure is notorious since films deposited at high pressures are more compact, presenting low oxygen incorporation after deposition. The increase of the substrate temperature up to 373 {\textdegree}K has the same effect, not changing the film{\textquoteright}s amorphous structure. These data will be discussed aiming to produce films with the required compactness and stoichiometry to grow very thin insulating layers (\<10 nm) to be used in MIS structures or devices like thin film transistors.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17144442271\&partnerID=40\&md5=d9bafec17045138904fdde243b1962b5}, author = {Pereira, L., {\'A}guas, H., Igreja, R., Martins, R.M.S., Nedev, N., Raniero, L., Fortunato, E., Martins, R.} } @article {Martins19961202, title = {Static and dynamic resolution of 1D thin film position sensitive detector}, journal = {Journal of Non-Crystalline Solids}, volume = {198-200}, number = {PART 2}, year = {1996}, note = {

cited By 5

}, pages = {1202-1206}, abstract = {

The aim of this work is to present a model to interpret the static and the dynamic detection and resolution limits of 1D thin film position sensitive detectors based on p-i-n a-Si:H devices. The model can determine the device characteristics that influence the spatial limits and the response time of the device.

}, doi = {10.1016/0022-3093(96)00113-5}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030563563\&partnerID=40\&md5=572b87c526f988ceb1b0cf7e4efc4c3b}, author = {Martins, R., Fortunato, E.} } @article {Martins1995143, title = {Static behaviour of thin-film position-sensitive detectors based on p-i-n a-Si:H devices}, journal = {Sensors and Actuators: A. Physical}, volume = {51}, number = {2-3}, year = {1995}, note = {

cited By 0

}, pages = {143-151}, abstract = {

The aim of this work is to provide the basis for the interpretation of the lateral photoeffect in p-i-n a-Si:H one-dimensional thin-film position-sensitive detectors (1D TFPSDs) under steady state, through an analytical model. The experimental data recorded in 1D TFPSD devices with different characteristics are compared with the predicted curves and the obtained correlations are discussed. {\textcopyright} 1996.

}, doi = {10.1016/0924-4247(95)01213-3}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029403161\&partnerID=40\&md5=62398d30f170086d9d3bbedb25d7d023}, author = {Martins, R., Fortunato, E.} } @article {Ferreira2013174, title = {Strongly photosensitive and fluorescent F8T2 electrospun fibers}, journal = {Macromolecular Materials and Engineering}, volume = {298}, number = {2}, year = {2013}, note = {

cited By 2

}, pages = {174-180}, abstract = {

Electrospun fibers of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-bithiophene] (F8T2) with exceptional electro-optical performance are obtained. The I/T characteristics measured in fibers with 7-15 μm diameter and 1 mm length show a semiconductor behavior; their thermal activation energy is 0.5 eV and the dark conductivity at RT is 5 {\texttimes} 10-9 (Ω cm)-1. Besides exhibiting a photosensitivity of about 60 under white light illumination with a light power intensity of 25 mW {\textperiodcentered} cm-2, the fibers also attain RT photoluminescence in the cyan, yellow, and red wavelength range under ultraviolet, blue, and green light excitation, respectively. Optical microscope images of F8T2 reveal homogeneous electrospun fibers, which are in good agreement with the uniformly radial fluorescence observed. The production of electrospun fibers from poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-bithiophene] (F8T2) obtained without a carrier polymer is reported. The obtained fibers are shown to have properties suitable for organic fiber photovoltaic and sensors applications. Copyright {\textcopyright} 2013 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/mame.201200009}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84873640727\&partnerID=40\&md5=a936ceb2510b94b51e41dd4b0cb82712}, author = {Ferreira, I.a , Baptista, A.C.a , Leit{\~a}o, J.P.b , Soares, J.b , Fortunato, E.a , Martins, R.a , Borges, J.P.a} } @article {Alves20091274, title = {Structural and optical properties of nitrogen doped ZnO films}, journal = {Vacuum}, volume = {83}, number = {10}, year = {2009}, note = {

cited By 8

}, pages = {1274-1278}, abstract = {

Zinc oxide is getting an enormous attention due to its potential applications in a variety of fields such as optoelectronics, spintronics and sensors. The renewed interest in this wide band gap oxide semiconductor relies on its direct high energy gap (Eg \~{} 3.437 eV at low temperatures) and large exciton binding energy. However to reach the stage of device production the difficulty to produce in a reproducible way p-type doping must be overcome. In this study we discuss the structural and optical properties of ZnO films doped with nitrogen, a potential p-type dopant. The films were deposited by magnetron sputtering using different conditions and substrates. The composition and structural properties of the films were studied combining X-ray diffraction (XRD), Rutherford backscattering (RBS), and heavy ion elastic recoil detection analysis (HI-ERDA). The results show an improvement of the quality of the films deposited on sapphire with increasing radio-frequency (RF) power with a preferentially growth along the c-axis. The ERDA analysis reveals the presence of H in the films and a homogeneous composition over the entire thickness. The photoluminescence of annealed samples evidences an improvement on the optical quality as identified by the well structured near band edge recombination. {\textcopyright} 2009 Elsevier Ltd. All rights reserved.

}, doi = {10.1016/j.vacuum.2009.03.022}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67349258288\&partnerID=40\&md5=055c51ce6efa482f28c9da1291fec8a2}, author = {Alves, E.a , Franco, N.a , Barradas, N.P.a , Munnik, F.b , Monteiro, T.c , Peres, M.c , Wang, J.d , Martins, R.d , Fortunato, E.} } @article {Fernandes200255, title = {Structural characterisation of NiTi thin film shape memory alloys}, journal = {Sensors and Actuators, A: Physical}, volume = {99}, number = {1-2}, year = {2002}, note = {

cited By 0

}, pages = {55-58}, abstract = {

Currently, microactuators are being developed using shape memory alloys (SMAs), which allow simple design geometries and provide large work outputs in restricted space. Several techniques have been used to produce NiTi shape memory alloy thin films, but from the practical point of view, only the sputter deposition method has succeeded so far. Vacuum evaporation of NiTi binary alloy entails the potential problem of the evaporation rates of each component not being the same due to differences in vapour pressure. Aiming to study the possible applications of SMAs to microfabrication, NiTi thin films were produced at CENIMAT by sputter and vacuum evaporation using raw materials from different sources. The films were analysed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) at room temperature, as well as in situ high temperature, in order to characterise the temperature ranges at which the different structural transformations occur. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0924-4247(01)00898-6}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037197289\&partnerID=40\&md5=0656458ec27af3ef3e11e1e31c970a07}, author = {Fernandes, F.M.Braz, Martins, R., Teresa Nogueira, M., Silva, R.J.C., Nunes, P., Costa, D., Ferreira, I., Martins, R.} } @article {Nunes2002599, title = {Structural characterisation of zinc oxide thin films produced by spray pyrolysis}, journal = {Key Engineering Materials}, volume = {230-232}, year = {2002}, note = {

cited By 4

}, pages = {599-602}, abstract = {

In this work, we present a study of the effect of temperature, type and concentration of the dopant on the structural characteristics of ZnO thin films produced by spray pyrolysis; the crystallite size has been determined from profile peak shape analysis. These results are compared to the electrical characterisation performed on these materials. The effect of the dopant on the properties of ZnO thin films depends on its characteristics, mainly its ionic radius. Al, Ga and In have been studied as dopants, the best one being In, since it leads to the lowest resistivity.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036436630\&partnerID=40\&md5=a1fc5601fd1094332e76790353c38704}, author = {Nunes, P., Braz Fernandes, F.M., Silva, R.J.C., Fortunato, E., Martins, R.} } @article {Parthiban20101554, title = {Structural, optical and electrical properties of indium-molybdenum oxide thin films prepared by spray pyrolysis}, journal = {Physica Status Solidi (A) Applications and Materials Science}, volume = {207}, number = {7}, year = {2010}, note = {

cited By 0

}, pages = {1554-1557}, abstract = {

Molybdenum doped indium oxide (IO) thin films were deposited on the Coring F1737 glass substrates at 400 {\textdegree}C by spray pyrolysis technique. TheModoping was varied between 0 and 4 at.\%. The films were characterized by their structural, electrical and optical properties. The films are confirmed to be cubic bixbyite In 2O 3 with a strongest orientation along (222) for 0.5 at.\% Mo, which is shifted to (400) plane when the Mo doping is increased to >=1.2 at.\%. The films deposited with 0.5 at.\% Mo showed high mobility of ̃90 cm 2/Vs, resistivity of ̃6.8{\texttimes}10 -4ωcm and carrier concentration of ̃1.01{\texttimes} 1020 cm -3 with \>̃73\% transmittance in the visible range between 500 and 800 nm. The transmittance is well extended into near infrared region.

}, doi = {10.1002/pssa.200983745}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955650024\&partnerID=40\&md5=f0b018108d1795c625f980d6c070bb4e}, author = {Parthiban, S.a , Elangovan, E.b , Ramamurthi, K.a , Goncalves, G.b , Martins, R.b , Fortunato, E.b} } @article {Santos2015, title = {Structure and morphologic influence of WO3 nanoparticles on the electrochromic performance of dual-phase a -WO3/WO3 inkjet printed films}, journal = {Advanced Electronic Materials}, volume = {1}, number = {1-2}, year = {2015}, note = {

cited By 5

}, abstract = {

The optimization of tungsten trioxide (WO3) nanoparticles produced via hydrothermal synthesis for application in electrochromic (EC) devices is reported. The structure and morphology of the nanoparticles are controlled by changing the acidity of the aqueous solvent added to the sol-gel precursor (peroxopolytungstic acid) during synthesis. Orthorhombic hydrated WO3 nanorods or monoclinic WO3 nanoslabs are obtained when HCl is added, while synthesis only in aqueous medium results in a mixture of both types of polymorphs. Dual-phase thin films are processed by inkjet printing deposition of the nanoparticles in flexible polyethylene terephthalate substrate with indium tin oxide coating (ITO PET) followed by the deposition of the precursor solution. When compared with purely amorphous tungsten oxide films, the dual phase ones present higher optical densities and improved capacity, and cyclability stability. The best results, obtained for orthorhombic hydrated nanoparticles (ortho -WO3 {\textperiodcentered}0.33H2 O), are due to its high surface area and improved conductivity. Additionally, the ex situ X-ray diffraction (XRD) lithiation studies show evidence of a higher distortion of the monoclinic when compared with the orthorhombic crystallographic structure, which contribute to the inferior EC performance. These results validate the use of inkjet printing deposition with low processing temperatures for EC dual-phase thin films containing optimized nanoparticles which are compatible with low-cost substrates. {\textcopyright} 2015 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/aelm.201400002}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973172254\&partnerID=40\&md5=cbd9c9806751d46bca66f99a18e07c3f}, author = {Santos, L.a , Wojcik, P.a , Pinto, J.V.a , Elangovan, E.b , Viegas, J.b , Pereira, L.a , Martins, R.a , Fortunato, E.a} } @article {Martins1997249, title = {Structure, composition and electro-optical properties of n-type amorphous and microcrystalline silicon thin films}, journal = {Philosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties}, volume = {76}, number = {3}, year = {1997}, note = {

cited By 5

}, pages = {249-258}, abstract = {

This paper deals with the structure, composition and electro-optical characteristics of n-type amorphous and microcrystalline silicon thin films produced by plasma-enhanced chemical vapour deposition in a hydrogenhelium mixture. In addition, special emphasis is given to the role that hydrogen incorporation plays in the film{\textquoteright}s properties and in the characteristics of n-type microcrystalline films presenting simultaneously optical gaps of about 2{\textperiodcentered}3 eV (controlled by the hydrogen content in the film), a dark conductivity of 6-5S cm-1 and a Hall mobility of about 0{\textperiodcentered}86 cm2 V-1 s-1, the highest combined values for n-type microcrystalline silicon films, as far as we know.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-5844325540\&partnerID=40\&md5=be5eed20e14af737b3c546b30d1787f5}, author = {Martins, R., Ma{\c c}arico, A., Vieira, M., Ferreira, I., Fortunato, E.} } @article {Alves20131, title = {Study and characterization of a novel polymer electrolyte based on agar doped with magnesium triflate}, journal = {Molecular Crystals and Liquid Crystals}, volume = {570}, number = {1}, year = {2013}, note = {

cited By 4

}, pages = {1-11}, abstract = {

In the present work one host natural matrix - agar - has been doped with magnesium triflate (Mg(CF3SO3)2) with the goal of developing electrolytes for the fabrication of solid-state devices. The resulting samples have been represented by the notation Agar nMg(CF3SO3)2, where n represents the percentage of the magnesium triflate salt proportion in the electrolyte samples. The samples investigated, with n between 0.00\% and 37.56\%, have been obtained as transparent and thin films. The samples have been characterized by conductivity measurements, thermal analysis, cyclic voltammetry, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The agar-based electrolytes were also tested as ionic conductor in an electrochromic device with the following configuration: glass/indium tin oxide (ITO)/WO 3/agar-based electrolyte/CeO2-TiO2/ITO/glass. {\textcopyright} 2013 Copyright Taylor and Francis Group, LLC.

}, doi = {10.1080/15421406.2012.703041}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84873373103\&partnerID=40\&md5=250060e87814655ad220460c4aa1bc7f}, author = {Alves, R.D.a , Rodrigues, L.C.a , Andrade, J.R.b , Pawlicka, A.b , Pereira, L.c , Martins, R.c , Fortunato, E.c , Silva, M.M.a} } @article {Meng1995673, title = {Study of annealed indium tin oxide films prepared by rf reactive magnetron sputtering}, journal = {Vacuum}, volume = {46}, number = {7}, year = {1995}, note = {

cited By 75

}, pages = {673-680}, abstract = {

Tin doped indium oxide (ITO) films were deposited on glass substrates by rf reactive magnetron sputtering using a metallic alloy target (In-Sn, 90-10). The post-deposition annealing has been done for ITO films in air and the effect of annealing temperature on the electrical, optical and structural properties of ITO films was studied. It has been found that the increase of the annealing temperature will improve the film electrical properties. The resistivity of as deposited film is about 1.3 {\texttimes} 10-1 gW*cm and decreases down to 6.9 {\texttimes} 10-3 Ω*cm as the annealing temperature is increased up to 500 {\textdegree}C. In addition, the annealing will also increase the film surface roughness which can improve the efficiency of amorphous silicon solar cells by increasing the amount of light trapping. {\textcopyright} 1995.

}, doi = {10.1016/0042-207X(94)00150-2}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029346777\&partnerID=40\&md5=8b31614b759b012fa8a14e31182ca4bd}, author = {Meng, L.-j., Ma{\c c}arico, A., Martins, R.} } @article {Gon{\c c}alves200683, title = {Study of electrochromic devices incorporating a polymer gel electrolyte component}, journal = {Materials Science Forum}, volume = {514-516}, number = {PART 1}, year = {2006}, note = {

cited By 1

}, pages = {83-87}, abstract = {

Electrochromic materials have attracted considerable attention during the last two decades as a consequence of their potential application in several different types of optical devices. Examples of these devices include intelligent windows and time labels. In this paper the authors describe results obtained with thin tungsten oxide films produced at room temperature by rf magnetron sputtering under an argon and oxygen atmosphere on transparent conductive oxide coated glass substrates. To protect the surface of the electrochromic film, prevent water absorption and obtain a good memory effect under open circuit voltages, a layer of Ta2O5 was deposited over the WO3 films. In this study, the effect of different electrolyte compositions on the open circuit memory of optical devices has been characterized. The best results were obtained for electrochromic devices with polymer gel p(TMC)3LiC1O4 and p(TMC)8LiClO 4 electrolytes. These prototype devices present an overall transmittance of \~{}75\% in their bleached state and after coloration 40.5 and 52.5\% respectively. These devices also show memory effect and an optical density considered satisfactory for some electrochromic applications.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-37849035931\&partnerID=40\&md5=052c76ced32246a0b57e6d48b24f8ab2}, author = {Gon{\c c}alves, A.a c , Gon{\c c}alves, G.a , Fortunato, E.a , Marques, A.a c , Pimentel, A.a , Martins, R.a , Silva, M.b , Smith, M.b , B} } @article {Gon{\c c}alves2012791, title = {Study of electrochromic devices with nanocomposites polymethacrylate hydroxyethylene resin based electrolyte}, journal = {Polymers for Advanced Technologies}, volume = {23}, number = {4}, year = {2012}, note = {

cited By 8

}, pages = {791-795}, abstract = {

This paper reports the application of a polymethacrylate hydroxyethylene resin based electrolyte in electrochromic (EC) devices. The electrolyte is characterized by electrochemical impedance spectroscopy, visible spectroscopy, TGA, DSC, and DRX and tested as an ionic conductor in an EC device with the following configuration: Substrate/IZO/WO 3/Polymer Electrolyte/(CeO 2)TiO 2/IZO/Substrate. The electrolyte presents an ionic conductivity of 10 -7S/cm at room temperature and TGA analysis show that electrolyte is thermally degraded at 200{\textdegree}C. The EC device based on this polymethacrylate hydroxyethylene resin electrolyte system shows memory effect and exhibits an excellent optical density. {\textcopyright} 2011 John Wiley \& Sons, Ltd.

}, doi = {10.1002/pat.1966}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84858291863\&partnerID=40\&md5=82054ad7b77f6003f665907760ff242a}, author = {Gon{\c c}alves, A.a , Costa, C.a c , Pereira, S.a , Correia, N.a , Silva, M.M.b , Barbosa, P.C.b , Rodrigues, L.C.b , Henriques, I.c} } @article {{\'A}guas20081215, title = {Study of environmental degradation of silver surface}, journal = {Physica Status Solidi (C) Current Topics in Solid State Physics}, volume = {5}, number = {5}, year = {2008}, note = {

cited By 3

}, pages = {1215-1218}, abstract = {

To evaluate the evolution of a dark film formation on silver surface objects, several coupons were catalogued and place inside a museum, located in an urban area. The changes on these samples were measured by spectroscopic ellipsometry, in periods of months. This technique allows the reduction of the coupons exposure time, in several months, due to its high sensitivity to surface modifications, with acceptable results for the evaluation of its degradation. The thicknesses of the degradation layers and the optical properties of silver oxide, chloride and sulphide reference samples were determined using a mixture of Tauc-Lorentz and Drude models. The composition of the silver corrosion layer was determined by fitting the layer using a Bruggeman Effective Medium Approximation (BEMA) of the three products plus voids. It was found that the thickness of the layer depends in the placement of the coupons, namely, inside or outside displayers. The average film thickness after 6 months was of 180 {\r A} and 280 {\r A}, inside and outside the displayers, respectively. The main compounds found in the layers were the silver chlorides and sulphides, which composition changed with the thickness of the layer, and the exposition time. {\textcopyright} 2008 Wiley-VCH Verlag GmbH \& Co. KGaA.

}, doi = {10.1002/pssc.200777842}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77951105817\&partnerID=40\&md5=53ae29e6e2ac274cc303abb7625fc424}, author = {{\'A}guas, H., Silva, R.J.C., Viegas, M., Pereira, L., Fortunato, E., Martins, R.} } @article {Zhang200618, title = {The study of high temperature annealing of a-SiC:H films}, journal = {Materials Science Forum}, volume = {514-516}, number = {PART 1}, year = {2006}, note = {

cited By 0

}, pages = {18-22}, abstract = {

A series of amorphous silicon carbide films were prepared by plasma enhanced chemical vapor deposition technique on (100) silicon wafers by using methane, silane, and hydrogen as reactive resources. A very thin (around 15 {\r A}) gold film was evaporated on the half area of the a-SiC:H films to investigate the metal induced crystallization effect. Then the a-SiC:H films were annealed at 1100{\textdegree}C for 1 hour in the nitrogen atmosphere. Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), and scanning electron microscopy (SEM) were employed to analyze the microstructure, composition and surface morphology of the films. The influences of the high temperature annealing on the microstructure of a-SiC:H film and the metal induced metallization were investigated.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-37849042787\&partnerID=40\&md5=5d3bdff9010ec23186195b993f01d998}, author = {Zhang, S.a , Hu, Z.a , Raniero, L.a , Liao, X.b , Ferreira, I.a , Fortunato, E.a , Vilarinho, P.c , Perreira, L.a , Martins, R.a} } @article {Raniero20061945, title = {Study of nanostructured silicon by hydrogen evolution and its application in p-i-n solar cells}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 14

}, pages = {1945-1948}, abstract = {

Nanostructured silicon films were deposited on the amorphous to microcrystalline transition region by plasma enhanced chemical vapor deposition, using an rf frequency of 27.12 MHz. Micro-Raman spectroscopy data show that in the transition region the peaks typically associated with amorphous silicon are slightly shifted towards higher wavenumber and become narrow, which could be explained by the short range order improvement or by the incorporation of very small Si nanocrystallites. The hydrogen evolution spectra from samples deposited in this region show two peaks, one at low temperature (LT) and the other at high temperature (HT), around 698 K and 840 K, respectively. These peaks represent activation energies of 87 (LT) and 135 (HT) kJ/mol, respectively, as deduced from the so-called Kissinger{\textquoteright}s method. The solar cells fabricated using i-layers produced in this transition region show good performances, with current density = 14.96 mA/cm2, short circuit voltage = 0.95 V, and fill factor = 0.67, which leads to efficiencies of 9.52\%. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2006.02.015}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33744523006\&partnerID=40\&md5=48f25098f3f3b982f5eb9da0e38f92af}, author = {Raniero, L., Ferreira, I., Pereira, L., {\'A}guas, H., Fortunato, E., Martins, R.} } @article {Raniero20061880, title = {Study of nanostructured/amorphous silicon solar cell by impedance spectroscopy technique}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 18

}, pages = {1880-1883}, abstract = {

This work deals with the study of nanostructured/amorphous silicon solar cell deposited by plasma enhanced chemical vapor deposition at 27.12 MHz by impedance spectroscopy. The solar cell studied present fill factor of 0.67, open circuit voltage of 0.94 V and short-circuit current density of 14.48 mA/cm2, which leads to the efficiency of 9.12\%. The impedance spectroscopy analysis was performed under dark and illumination conditions. The data obtained were used to define an electrical equivalent circuit model able to explain the role of the different solar cell components, including the interfaces, on the solar cell performance. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2006.02.023}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33745470255\&partnerID=40\&md5=2e0a7d28bb772e2a390f43ed38bd314e}, author = {Raniero, L., Fortunato, E., Ferreira, I., Martins, R.} } @article {{\'A}guas2000475, title = {Study of the effect of different plasma-enhanced chemical vapour deposition reactor configurations on the properties of hydrogenated amorphous silicon thin films}, journal = {Philosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties}, volume = {80}, number = {4}, year = {2000}, note = {

cited By 12

}, pages = {475-486}, abstract = {

In this work we present a study performed in a plasma-enhanced chemical vapour deposition reactor, where different rf electrode configurations were used with the aim of achieving conditions that lead to growth of highly uniform amorphous silicon films, with the required electronic quality, at high growth rates. This study consists in determining the plasma characteristics under different electrode configurations, in an argon plasma, using as diagnostic tools a Langmuir probe and impedance probe. These results were correlated with the hydrogenated amorphous silicon films produced, thereby allowing us to establish the best electrode configuration to grow electronic-grade-quality amorphous silicon films.

}, doi = {10.1080/014186300255122}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034175284\&partnerID=40\&md5=8a75b1f36ef95bdb8f756b9511373cde}, author = {{\'A}guas, H., Silva, V., Ferreira, I., Fortunato, E., Martins, R.} } @article {Lopes2002357, title = {Study of the sensing mechanism of SnO2 thin-film gas sensors using hall effect measurements}, journal = {Key Engineering Materials}, volume = {230-232}, year = {2002}, note = {

cited By 1

}, pages = {357-360}, abstract = {

Hall effect measurements are one of the most powerful techniques for obtaining information about the conduction mechanism in polycrystalline semiconductor materials, which is the basis for understanding semiconductor gas sensors. In order to investigate the correlation between the microscopic characteristics and the macroscopic performances exhibited by undoped tin oxide gas sensors deposited by spray pyrolysis, Hall effect measurements were performed at different temperatures, from room temperature up to 500 K, and in the presence of two different atmospheres, air and methane. From these measurements, it was possible to infer the potential barrier and its dependence with the used atmosphere. The obtained results were analysed in terms of the oxygen mechanism at grain boundaries on the basis of the grain boundary-trapping model. In the presence of methane gas, the electrical resistivity decreases due to the lowering of the inter-grain boundary barrier height.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036432225\&partnerID=40\&md5=4fac5ab5a508bad2f6a93846618e74ba}, author = {Lopes, A., Nunes, P., Vilarinho, P., Monteiro, R., Fortunato, E., Martins, R.} } @article {Barquinha200668, title = {A study on the electrical properties of ZnO based transparent TFTs}, journal = {Materials Science Forum}, volume = {514-516}, number = {PART 1}, year = {2006}, note = {

cited By 1

}, pages = {68-72}, abstract = {

The purpose of this work is to present in-depth electrical characterization on transparent TFTs, using zinc oxide produced at room temperature as the semiconductor material. Some of the studied aspects were the relation between the output conductance in the post-pinch-off regime and width-to-length ratios, the gate leakage current, the semiconductor/insulator interface traps density and its relation with threshold voltage. The main point of the analysis was focused on channel mobility. Values extracted using different methodologies, like effective, saturation and average mobility, are presented and discussed regarding their significance and validity. The evolution of the different types of mobility with the applied gate voltage was investigated and the obtained results are somehow in disagreement with the typical behavior found on classical silicon based MOSFETs, which is mainly attributed to the completely different structures of the semiconductor materials used in the two situations: while in MOSFETS we have monocrystalline silicon, our transparent TFTs use poly/nanocrystalline zinc oxide with grain sizes of about 10 nm.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-37849054243\&partnerID=40\&md5=06197e90df02671fbbc2d8beddabb256}, author = {Barquinha, P., Fortunato, E., Gon{\c c}alves, A., Pimentel, A., Marques, A., Pereira, L., Martins, R.} } @article {Bregman19892628, title = {Substrate effect on the electrical properties of a-Si:H thin films and its modification by diffusion-blocking interlayers}, journal = {Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films}, volume = {7}, number = {4}, year = {1989}, note = {

cited By 1

}, pages = {2628-2631}, abstract = {

Electrical dark conductivity (σd) and surface composition of undoped and doped a-Si:H thin films have been investigated, using coplanar I-V as a function of temperature and Auger electron spectroscopy (AES). The films were prepared by rf glow discharge deposition on standard soda-lime glass and on alkali-free glass substrates. Comparing these two sets of substrates for undoped films, we find that σd of the films deposited on soda-lime glass substrates at room temperature is higher by more than two orders of magnitude, their activation energy is lower by about a factor of 3, and their photosensitivity (σph/σd) is lower by two orders of magnitude than that of the films deposited on alkali-free glass substrates. We suggest that Na ions, leached from the glass into the a-Si:H overlayer play a significant role in determining the film conductivity by creating electrically active donorlike states. This conclusion is supported by similar measurements on p- and n-type a-Si:H films on the same substrates and by AES results. Films of a-Si:H, grown on thin a-Si:C:H interlayers on soda-lime glass, showed very low Na concentrations and low dark conductivities as found by AES and electrical measurements, respectively. The role of the a-Si:C:H interlayers as diffusion barriers is discussed. {\textcopyright} 1989, American Vacuum Society. All rights reserved.

}, doi = {10.1116/1.575808}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-80055052298\&partnerID=40\&md5=33d14f72a46491a6b0eea033ecc7c72c}, author = {Bregman, J.a , Gordon, J.a , Shapira, Y.a , Fortunato, E.b , Martins, R.b , Guimaraes, L.b} } @article {Deuermeier2016, title = {Substrate reactivity as the origin of Fermi level pinning at the Cu2O/ALD-Al2O3 interface}, journal = {Materials Research Express}, volume = {3}, number = {4}, year = {2016}, note = {

cited By 1

}, abstract = {

The reduction of aCu2O layer on copper by exposure toTMAduring the atomic layer deposition of Al2O3 has recently been reported. (Gharachorlou et al 2015 ACS Appl. Mater. Interfaces 7 16428-16439). The study presented here analyzes a similar process, leading to the reduction of a homogeneous Cu2O thin film, which allows for additional observations. Angle-resolved in situ X-ray photoelectron spectroscopy confirms the localization of metallic copper at the interface. The evaluation of binding energy shifts reveals the formation of aCu2O/Cu Schottky barrier, which gives rise to Fermi level pinning in Cu2O. An initial enhancement of the ALD growth per cycle (GPC) is only observed for bulk Cu2O samples and is thus related to lattice oxygen, originating from regions lying deeper than just the first few layers of the surface. The oxygen out-take from the substrate is limited to the first few cycles, which is found to be due to a saturated copper reduction, rather than the oxygen diffusion barrier of Al2O3. {\textcopyright} 2016 IOP Publishing Ltd.

}, doi = {10.1088/2053-1591/3/4/046404}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84965078708\&partnerID=40\&md5=c38e23a8046a47a1649b8d681d4ec18a}, author = {Deuermeier, J.a b , Bayer, T.J.M.b d , Yanagi, H.c , Kiazadeh, A.a , Martins, R.a , Klein, A.b , Fortunato, E.a} } @article {{\'A}guas20051088, title = {Super linear position sensitive detectors using MIS structures}, journal = {Optical Materials}, volume = {27}, number = {5}, year = {2005}, note = {

cited By 11

}, pages = {1088-1092}, abstract = {

This work reports on the fabrication process and performances presented by metal insulator semiconductor (MIS) linear position sensitive detectors (PSD) with an active length of 6 cm. The use of long sensitive areas allows the PSD to achieve higher resolution without the need of a highly accurate light spot integration mechanism. The PSD is built in a multilayered structure consisting of Cr/a-Si:H (n+ doped)/a-Si:H (intrinsic)/SiOx (passivation layer)/Au, where the active a-Si:H layers were deposited by a modified triode plasma enhanced chemical vapour deposition (MTPECVD), which allows the deposition of highly electronic grade material with a low (≈ {\texttimes} 1015 cm-3) defect density inferred by CPM. The sensor linearity and sensitivity shows dependence on the sensor width to length ratio and on the value of load resistance. Sensitivities of more than 30 mV/cm were achieved with linearity near 99\%. Besides that, this type of MIS structure allows an improved spectral response near the UV region and has the maximum response at 540 nm. {\textcopyright} 2004 Published by Elsevier B.V.

}, doi = {10.1016/j.optmat.2004.08.067}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-13544275669\&partnerID=40\&md5=0687681e0c5516f739c681629e8927a6}, author = {{\'A}guas, H., Pereira, L., Costa, D., Fortunato, E., Martins, R.} } @article {Fortunato2003127, title = {Surface modification of a new flexible substrate based on hydroxypropylcellulose for optoelectronic applications}, journal = {Thin Solid Films}, volume = {442}, number = {1-2}, year = {2003}, note = {

cited By 9

}, pages = {127-131}, abstract = {

In this paper, we present the preliminary results concerning the deposition of highly transparent and conductive gallium-doped zinc oxide (GZO) deposited on transparent flexible substrate based on cellulose derivatives. Prior to the deposition of the GZO film, the surface of the polymer have been coated with a thin silicon dioxide (SiO2) layer deposited by thermal evaporation assisted by an electron gun. By doing this surface treatment, we succeeded in depositing highly conductive and transparent GZO with an electrical resistivity of 2.0 {\texttimes} 10-3 Ω cm and an average optical transmittance in the visible part of the spectrum (400-700 nm) of 70\% by r.f. magnetron sputtering at room temperature. Besides the optoelectronic properties, the films are mechanically stable with a polycrystalline structure with a strong preferred (002) orientation, parallel to the substrate. {\textcopyright} 2003 Elsevier B.V. All rights reserved.

}, doi = {10.1016/S0040-6090(03)00959-3}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0141748211\&partnerID=40\&md5=6bd45abbe1536770902b58fddb415c3c}, author = {Fortunato, E., Godinho, M.H., Santos, H., Marques, A., Assun{\c c}{\~a}o, V., Pereira, L., {\'A}guas, H., Ferreira, I., Martins, R.} } @article {Mei2002155, title = {Synthesis, characterization, and processing of cordierite-glass particles modified by coating with an alumina precursor}, journal = {Journal of the American Ceramic Society}, volume = {85}, number = {1}, year = {2002}, note = {

cited By 6

}, pages = {155-160}, abstract = {

The surfaces of cordierite and glass particles were modified by coating them with an alumina precursor using a precipitation process in the presence of urea. Scanning electron microscopy (SEM), high-resolution transmission electron microscopy, X-ray diffraction, electrophoresis, and rheological measurements were used to characterize the coated powders. SEM and transmission electron microscopy morphologies of the coated powders revealed that amorphous and homogeneous coatings have been formed around the particles. The morphology of the coated powders showed a coiled wormlike surface. The coating Al2O3 layer dominated the surface properties of the coated glass and cordierite powders. The influence of the coating layer on the processing ability of cordierite-based glass-ceramics substrates by tape casting was studied in aqueous media. It could be concluded that the coating of the powders facilitates the processing and yields green and sintered tapes with denser, more homogeneous microstructures compared with the uncoated powders.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036346830\&partnerID=40\&md5=1d6c31c9990a13c7977f4309d04bcc1c}, author = {Mei, S., Yang, J., Monteiro, R., Martins, R., Ferreira, J.M.F.} } @article {Martins1993671, title = {Tailoring defects on amorphous silicon pin devices}, journal = {Journal of Non-Crystalline Solids}, volume = {164-166}, number = {PART 2}, year = {1993}, note = {

cited By 13

}, pages = {671-674}, abstract = {

This paper deals with a new model and structure able to tailor defects in pin devices. The model assumes the usual density of states profile, including donor and acceptor like states inside the mobility gap and has the capability to simulate the transient and steady state device behavior. The new structure is based in two interfacial defectous layers, located at the junctions, acting as "gettering" centers to tailor the defects. The role of the interlayer and its thickness on device performances will be also discussed. {\textcopyright} 1993.

}, doi = {10.1016/0022-3093(93)91087-J}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027906850\&partnerID=40\&md5=820421f6a25492df214107ec99a3bab0}, author = {Martins, R., Fantoni, A., Vieira, M.} } @article {Wojcik20151696, title = {Tailoring nanoscale properties of tungsten oxide for inkjet printed electrochromic devices}, journal = {Nanoscale}, volume = {7}, number = {5}, year = {2015}, note = {

cited By 4

}, pages = {1696-1708}, abstract = {

This paper focuses on the engineering procedures governing the synthesis of tungsten oxide nanocrystals and the formulation of printable dispersions for electrochromic applications. By that means, we aim to stress the relevancy of a proper design strategy that results in improved physicochemical properties of nanoparticle loaded inks. In the present study inkjet printable nanostructured tungsten oxide particles were successfully synthesized via hydrothermal processes using pure or acidified aqueous sol-gel precursors. Based on the proposed scheme, the structure and morphology of the nanoparticles were tailored to ensure the desired printability and electrochromic performance. The developed nanomaterials with specified structures effectively improved the electrochemical response of printed films, resulting in 2.5 times higher optical modulation and 2 times faster coloration time when compared with pure amorphous films. {\textcopyright} The Royal Society of Chemistry 2015.

}, doi = {10.1039/c4nr05765a}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84921745348\&partnerID=40\&md5=a13a8ccc218497e339a2b91f1d570e9b}, author = {Wojcik, P.J., Santos, L., Pereira, L., Martins, R., Fortunato, E.} } @article {Grigore1999409, title = {Thermodynamic properties of ternary aqueous electrolyte solutions}, journal = {Physics and Chemistry of Liquids}, volume = {37}, number = {4}, year = {1999}, note = {

cited By 0

}, pages = {409-428}, abstract = {

In previous papers the mean excess chemical potential, μ1(E), in ternary systems of the type I sulphate + II sulphate + H2O, at 25{\textdegree}C was determined. Results obtained for systems with CuSO4(I), and ZnSO4(I) respectively, pointed out an obvious disparity between their behaviours. They show the existence of some important association phenomena partially accounting for the substantial deviations from ideal behaviour. The ternary sulphate systems (CuSO4 + Me(I,II)SO4 + H2O; ZnSO4 + Me(I,II)SO4 + H2O) studied were characterized against the binaries of the same ionic strength, experimental data being obtained using both e.m.f. and spectrophotometric methods. Deviations from the ideal behaviour were discussed in terms of thermodynamic excess functions and association constants. A comparative study between the results obtained with the two above mentioned methods is presented. In previous papers the mean excess chemical potential, μ1 E, in ternary systems of the type I sulphate+II sulphate+H2O, at 25 {\textdegree}C was determined. Results obtained for systems with CuSO4(I), and ZnSO4(I) respectively, pointed out an obvious disparity between their behaviours. They show the existence of some important association phenomena partially accounting for the substantial deviations from ideal behaviour. The ternary sulphate systems (CuSO4+MeI, IISO4+H2O; ZnSO4+MeI, IISO4+H2O) studied were characterized against the binaries of the same ionic strength, experimental data being obtained using both e.m.f. and spectrophotometric methods. Deviations from the ideal behaviour were discussed in terms of thermodynamic excess functions and association constants. A comparative study between the results obtained with the two above mentioned methods is presented.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033379283\&partnerID=40\&md5=7b7aba93774abf157a0b942086554bdb}, author = {Grigore, L.a , Meghea, A.b , Grigore, O.c , Martins, R.a} } @article {Santos2013590, title = {Thermoelectric properties of V2O5 thin films deposited by thermal evaporation}, journal = {Applied Surface Science}, volume = {282}, year = {2013}, note = {

cited By 19

}, pages = {590-594}, abstract = {

This work reports the structural, optical, electrical and thermoelectric properties of vanadium pentoxide (V2O5) thin films deposited at room temperature by thermal evaporation on Corning glass substrates. A post-deposition thermal treatment up to 973 K under atmospheric conditions induces the crystallization of the as-deposited amorphous films with an orthorhombic V2O5 phase with grain sizes around 26 nm. As the annealing temperature rises up to 773 K the electrical conductivity increases. The films exhibit thermoelectric properties with a maximum Seebeck coefficient of -218 μV/K and electrical conductivity of 5.5 (Ω m) -1. All the films show NIR-Vis optical transmittance above 60\% and optical band gap of 2.8 eV. {\textcopyright} 2013 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.apsusc.2013.06.016}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84880928318\&partnerID=40\&md5=4699a3dca129783c1ef8bae6257fc631}, author = {Santos, R., Loureiro, J., Nogueira, A., Elangovan, E., Pinto, J.V., Veiga, J.P., Busani, T., Fortunato, E., Martins, R., Ferreir} } @article {Baptista20112742, title = {Thin and flexible bio-batteries made of electrospun cellulose-based membranes}, journal = {Biosensors and Bioelectronics}, volume = {26}, number = {5}, year = {2011}, note = {

cited By 13

}, pages = {2742-2745}, abstract = {

The present work proposes the development of a bio-battery composed by an ultrathin monolithic structure of an electrospun cellulose acetate membrane, over which was deposited metallic thin film electrodes by thermal evaporation on both surfaces. The electrochemical characterization of the bio-batteries was performed under simulated body fluids like sweat and blood plasma [salt solution - 0.9\% (w/w) NaCl]. Reversible electrochemical reactions were detected through the cellulose acetate structure. Thus, a stable electrochemical behavior was achieved for a bio-battery with silver and aluminum thin films as electrodes. This device exhibits the ability to supply a power density higher than 3μWcm-2.Finally, a bio-battery prototype was tested on a sweated skin, demonstrating the potential of applicability of this bio-device as a micropower source. {\textcopyright} 2010 Elsevier B.V.

}, doi = {10.1016/j.bios.2010.09.055}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-78650620172\&partnerID=40\&md5=ca3fd77344c151d6407e00a5f6d06a09}, author = {Baptista, A.C.a , Martins, J.I.b , Fortunato, E.a , Martins, R.a , Borges, J.P.a , Ferreira, I.a} } @article {Fortunato19943784, title = {Thin film position sensitive detector based on amorphous silicon p-i-n diode}, journal = {Review of Scientific Instruments}, volume = {65}, number = {12}, year = {1994}, note = {

cited By 35

}, pages = {3784-3786}, abstract = {

The application of hydrogenated amorphous silicon (a-Si:H) to optoelectronic devices are now well established as a viable low cost technology and is presently receiving much interest. Taking advantage of the properties of a-Si:H based devices, single and dual axis large area (up to 80{\texttimes}80 mm 2) thin film position sensitive detectors (TFPSD) based on a-Si:H p-i-n diodes have been developed, produced by plasma enhanced chemical vapor deposition. In this study, the main optoelectronic properties presented by the TFPSD as well as their behavior under operation conditions, concerning its linearity and signal to noise ratio, are reported. {\textcopyright} 1994 American Institute of Physics.

}, doi = {10.1063/1.1144507}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001457335\&partnerID=40\&md5=395797faedacff2a232621f8118be023}, author = {Fortunato, E., Lavareda, G., Vieira, M., Martins, R.} } @article {Cabrita2001443, title = {Thin film position sensitive detectors based on pin amorphous silicon carbide structures}, journal = {Applied Surface Science}, volume = {184}, number = {1-4}, year = {2001}, note = {

cited By 11

}, pages = {443-447}, abstract = {

The performances of silicon carbide position sensitive detectors in relation to position color selection applications were presented. The devices were deposited on glass substrates coated with a transparent conductive oxide layer based on indium tin oxide film (ITO). On top of the ITP layer a pin structure produced by plasma enhanced chemical vapor deposition technique was deposited. The set of data achieved indicated that the undoped silicon carbide layers presented a low density of states, which explained high dark conductivity values obtained and the type of performances recorded on the PSD devices produced.

}, doi = {10.1016/S0169-4332(01)00532-3}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035852220\&partnerID=40\&md5=de19a97f8d94f6c3dc257ae7c8a44d48}, author = {Cabrita, A., Figueiredo, J., Pereira, L., {\'A}guas, H., Silva, V., Brida, D., Ferreira, I., Fortunato, E., Martins, R.} } @article {{\'A}guas20153592, title = {Thin Film Silicon Photovoltaic Cells on Paper for Flexible Indoor Applications}, journal = {Advanced Functional Materials}, volume = {25}, number = {23}, year = {2015}, note = {

cited By 7

}, pages = {3592-3598}, abstract = {

The present development of non-wafer-based photovoltaics (PV) allows supporting thin film solar cells on a wide variety of low-cost recyclable and flexible substrates such as paper, thereby extending PV to a broad range of consumer-oriented disposable applications where autonomous energy harvesting is a bottleneck issue. However, their fibrous structure makes it challenging to fabricate good-performing inorganic PV devices on such substrates. The advances presented here demonstrate the viability of fabricating thin film silicon PV cells on paper coated with a hydrophilic mesoporous layer. Such layer can not only withstand the cells production temperature (150 C), but also provide adequate paper sealing and surface finishing for the cell{\textquoteright}s layers deposition. The substances released from the paper substrate are continuously monitored during the cell deposition by mass spectrometry, which allows adapting the procedures to mitigate any contamination from the substrate. In this way, a proof-of-concept solar cell with 3.4\% cell efficiency (41\% fill factor, 0.82 V open-circuit voltage and 10.2 mA cm-2 short-circuit current density) is attained, opening the door to the use of paper as a reliable substrate to fabricate inorganic PV cells for a plethora of indoor applications with tremendous impact in multi-sectorial fields such as food, pharmacy and security. {\textcopyright} 2015 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/adfm.201500636}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84931268053\&partnerID=40\&md5=dfb55cbfad2d3fca62fa3665d4471360}, author = {{\'A}guas, H.a , Mateus, T.a , Vicente, A.a , Gaspar, D.a , Mendes, M.J.a , Schmidt, W.A.b , Pereira, L.a , Fortunato, E.a , Martins} } @article {{\'A}guas2015, title = {Thin Film Silicon Photovoltaic Cells on Paper for Flexible Indoor Applications}, journal = {Advanced Functional Materials}, year = {2015}, note = {

cited By 3; Article in Press

}, abstract = {

The present development of non-wafer-based photovoltaics (PV) allows supporting thin film solar cells on a wide variety of low-cost recyclable and flexible substrates such as paper, thereby extending PV to a broad range of consumer-oriented disposable applications where autonomous energy harvesting is a bottleneck issue. However, their fibrous structure makes it challenging to fabricate good-performing inorganic PV devices on such substrates. The advances presented here demonstrate the viability of fabricating thin film silicon PV cells on paper coated with a hydrophilic mesoporous layer. Such layer can not only withstand the cells production temperature (150 {\textdegree}C), but also provide adequate paper sealing and surface finishing for the cell{\textquoteright}s layers deposition. The substances released from the paper substrate are continuously monitored during the cell deposition by mass spectrometry, which allows adapting the procedures to mitigate any contamination from the substrate. In this way, a proof-of-concept solar cell with 3.4\% cell efficiency (41\% fill factor, 0.82 V open-circuit voltage and 10.2 mA cm-2 short-circuit current density) is attained, opening the door to the use of paper as a reliable substrate to fabricate inorganic PV cells for a plethora of indoor applications with tremendous impact in multi-sectorial fields such as food, pharmacy and security. {\textcopyright} 2015 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/adfm.201500636}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84929093558\&partnerID=40\&md5=e14701874348344ba9e13e19d768f60d}, author = {{\'A}guas, H.a , Mateus, T.a , Vicente, A.a , Gaspar, D.a , Mendes, M.J.a , Schmidt, W.A.b , Pereira, L.a , Fortunato, E.a , Martins} } @article {Fortunato1998421, title = {Thin films applied to integrated optical position-sensitive detectors}, journal = {Thin Solid Films}, volume = {317}, number = {1-2}, year = {1998}, note = {

cited By 3

}, pages = {421-424}, abstract = {

We have developed a linear thin film position-sensitive detector with 128 elements, based on p.i.n. a-Si:H devices. The incorporation of this sensor into an optical inspection camera makes possible the acquisition of three-dimensional information of an object, using laser triangulation methods. The main advantages of this system, when compared with the conventional charge-coupled devices, are the low complexity of hardware and software used, and that the information can be continuously processed (analogic detection). In this paper, we present the most significant characteristics of the singular one-dimensional thin film position-sensitive detectors that form part of the linear array with 128 sensors. {\textcopyright} 1998 Elsevier Science S.A.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032051033\&partnerID=40\&md5=d2e635546a9565c5b654203a403f5d00}, author = {Fortunato, E., Soares, F., Lavareda, G., Martins, R.} } @article {Fortunato19981230, title = {Thin oxide interface layers in a-Si:H MIS structures}, journal = {Journal of Non-Crystalline Solids}, volume = {227-230}, number = {PART 2}, year = {1998}, note = {

cited By 9

}, pages = {1230-1234}, abstract = {

Pd-metal/insulator/semiconductor based on hydrogenated amorphous silicon were produced by plasma enhanced chemical vapour deposition with two different oxidised surfaces: thermal in ambient air and chemical with hydrogen peroxide. The diode characteristics have been investigated using dark and light current as f(v) measurements in the temperature range from 300 K to 380 K, from which it was possible to infer the electron barrier height. The data obtained show that the incorporation of a thin insulator layer between the semiconductor and the metal improves the performances of the devices by preventing the formation of suicides at the interface. Apart from that we also show that the MIS structures with the thermal oxide presents {\textquoteright}better{\textquoteright} performances than the ones with the chemical oxide due to the type of interface states and of the oxide charges associated with the interface between the insulator and the semiconductor. {\textcopyright} 1998 Elsevier Science B.V. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032068749\&partnerID=40\&md5=49aa5b265f177734a9bdc5ec9653e0c4}, author = {Fortunato, E., Malik, A., Martins, R.} } @article {deNijs1991339, title = {A thin SiO layer as a remedy for the indium reduction at the In2O3/μc-Si:C:H interface}, journal = {Applied Surface Science}, volume = {52}, number = {4}, year = {1991}, note = {

cited By 5

}, pages = {339-342}, abstract = {

The reduction of the In2O3 caused by the deposition of μc-Si:C:H by means of plasma-enhanced CVD, is considerably diminished if a thin (50 {\r A}) silicon monoxide layer is applied as a diffusion barrier. The amount of reduced indium diminishes by a factor three while the amount of silicon oxide is also less, although SiO was added on purpose. First results on an amorphous silicon In2O3/pi junction show that the SiO layer benefits the opto-electrical characteristics. {\textcopyright} 1991.

}, doi = {10.1016/0169-4332(91)90077-W}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0026395801\&partnerID=40\&md5=90cd16b8ea0b4ba24c789fa47753abd3}, author = {de Nijs, J.M.M.a , Carvalho, C.b , Santos, M.b , Martins, R.b} } @article {Elangovan20111391, title = {Thin-film transistors based on indium molybdenum oxide semiconductor layers sputtered at room temperature}, journal = {IEEE Electron Device Letters}, volume = {32}, number = {10}, year = {2011}, note = {

cited By 6

}, pages = {1391-1393}, abstract = {

Thin-film transistors (TFTs) were fabricated using a 20-nm-thick indium molybdenum oxide (IMO) semiconductor layer at room temperature. The grazing incidence X-ray diffraction patterns confirmed that the deposited films are amorphous. The average transmittance (400-2500 nm) and the optical band gap are \~{}88\% and 3.95 eV, respectively. The TFTs fabricated on glass substrates showed a saturation mobility of 4.0 cm2/Vc s with an I ON/IOFF ratio of 2 {\texttimes} 103 and a threshold voltage of-1.1 V, which are encouraging preliminary results in order to develop IMO as high-performance semiconductor layer. {\textcopyright} 2011 IEEE.

}, doi = {10.1109/LED.2011.2162310}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-80053567839\&partnerID=40\&md5=757a63fef4d59d482f249522a6fddbca}, author = {Elangovan, E., Saji, K.J., Parthiban, S., Goncalves, G., Barquinha, P., Martins, R., Fortunato, E.} } @article {Fortunato2010, title = {Thin-film transistors based on p-type Cu2 O thin films produced at room temperature}, journal = {Applied Physics Letters}, volume = {96}, number = {19}, year = {2010}, note = {

cited By 65

}, abstract = {

Copper oxide (Cu2 O) thin films were used to produce bottom gate p-type transparent thin-film transistors (TFTs). Cu2 O was deposited by reactive rf magnetron sputtering at room temperature and the films exhibit a polycrystalline structure with a strongest orientation along (111) plane. The TFTs exhibit improved electrical performance such as a field-effect mobility of 3.9 cm2 /V s and an on/off ratio of 2{\texttimes} 102. {\textcopyright} 2010 American Institute of Physics.

}, doi = {10.1063/1.3428434}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77952959792\&partnerID=40\&md5=40d08de402d16256882deed5b7cf32b6}, author = {Fortunato, E.a , Figueiredo, V.a , Barquinha, P.a , Elamurugu, E.a , Barros, R.a b , Gonalves, G.a , Park, S.-H.K.c , Hwang, C.-} } @article {Pavan2015549, title = {TiO2/Cu2O all-oxide heterojunction solar cells produced by spray pyrolysis}, journal = {Solar Energy Materials and Solar Cells}, volume = {132}, year = {2015}, note = {

cited By 21

}, pages = {549-556}, abstract = {

Here we present for the first time a TiO2/Cu2O all-oxide heterojunction solar cell entirely produced by spray pyrolysis onto fluorine doped tin oxide (FTO) covered glass substrates, using silver as a back contact. A combinatorial approach was chosen to investigate the impact of the TiO2 window layer and the Cu2O light absorber thicknesses. We observe an open circuit voltage up to 350 mV and a short circuit current density which is strongly dependent of the Cu2O thickness, reaching a maximum of ~0.4 mA/cm2. Optical investigation reveals that a thickness of 300 nm spray pyrolysis deposited Cu2O is sufficient to absorb most photons with an energy above the symmetry allowed optical transition of 2.5 eV, indicating that the low current densities are caused by strong recombination in the absorber that consists of small Cu2O grains. {\textcopyright} 2014 Elsevier Ltd. All rights reserved.

}, doi = {10.1016/j.solmat.2014.10.005}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84908517773\&partnerID=40\&md5=44fb08ad9b940917039cd3b638700028}, author = {Pavan, M.a , R{\"u}hle, S.b , Ginsburg, A.b , Keller, D.A.b , Barad, H.-N.b , Sberna, P.M.c , Nunes, D.a , Martins, R.a , Anderson,} } @article {Barquinha2009, title = {Toward high-performance amorphous GIZO TFTs}, journal = {Journal of the Electrochemical Society}, volume = {156}, number = {3}, year = {2009}, note = {

cited By 171

}, pages = {H161-H168}, abstract = {

This work analyzes the role of processing parameters on the electrical performance of GIZO (Ga2 O3: In2 O3:ZnO) films and thin-film transistors (TFTs). Parameters such as oxygen partial pressure, deposition pressure, target composition, thickness, and annealing temperature are studied. Generally, better devices are obtained when low oxygen partial pressure is used. This is related to the damage induced by oxygen ion bombardment and very high film{\textquoteright}s resistivity when higher oxygen partial pressures are used. Low deposition pressures and targets with richer indium compositions led to films with high carrier concentration, resulting in transistors with field-effect mobility as high as \~{}80 cm2 Vs but poor channel conductivity modulation, becoming ineffective as switching devices. Nevertheless, it is demonstrated that reducing the GIZO thickness from 40 to 10 nm greatly enhances the switching behavior of those devices, due to the lower absolute number of free carriers and hence to their easier depletion. Annealing also proves to be crucial to control device performance, significantly modifying GIZO electrical resistivity and promoting local atomic rearrangement, being the optimal temperature determined by the as-produced films{\textquoteright} properties. For the best-performing transistors, even with a low annealing temperature (150{\textdegree}C), remarkable properties such as μFE =73.9 cm2 Vs, onoff ratio≈7{\texttimes} 107, VT ≈0.2 V, and S=0.29 Vdec are achieved. {\textcopyright} 2008 The Electrochemical Society.

}, doi = {10.1149/1.3049819}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-59349097224\&partnerID=40\&md5=56b6680c608990bc963bc5629d61e85b}, author = {Barquinha, P., Pereira, L., Gonalves, G., Martins, R., Fortunato, E.} } @article {Branquinho2015, title = {Towards environmental friendly solution-based ZTO/AlOx TFTs}, journal = {Semiconductor Science and Technology}, volume = {30}, number = {2}, year = {2015}, note = {

cited By 6

}, abstract = {

Solution based deposition has been recently considered as a viable option for low-cost flexible electronics. In this context research efforts have been increasingly centred on the development of suitable solution-processed materials for oxide based transistors. Nevertheless, the majority of synthetic routes reported require the use of toxic organic solvents. In this work we report on a new environmental friendly solution combustion synthesis route, using ethanol as solvent, for the preparation of indium/gallium free amorphous zinc-tin oxide (ZTO) thin film transistors (TFTs) including AlOx gate dielectric. The decomposition of ZTO and AlOx precursor solutions, electrical characterization and stability of solution processed ZTO/AlOx TFTs under gate-bias stress, in both air and vacuum atmosphere, were investigated. The devices demonstrated low hysteresis (ΔV=0.23 V), close to zero turn on voltage, low threshold voltage (VT=0.36 V) and a saturation mobility of 0.8 cm2 V-1 s-1 at low operation voltages. Ethanol based ZTO/AlOx TFTs are a promising alternative for applications in disposable, low cost and environmental friendly electronics. {\textcopyright} 2015 IOP Publishing Ltd.

}, doi = {10.1088/0268-1242/30/2/024007}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84921472053\&partnerID=40\&md5=a983e098d50d10a507ee19fc02467ceb}, author = {Branquinho, R., Salgueiro, D., Santa, A., Kiazadeh, A., Barquinha, P., Pereira, L., Martins, R., Fortunato, E.} } @article {Martins2000257, title = {Towards the improvement of the stability of a-Si:H pin devices}, journal = {Solar Energy}, volume = {69}, number = {SUPPLEMENT}, year = {2000}, note = {

cited By 4

}, pages = {257-262}, abstract = {

This paper deals with a new process to improve the stability of a-Si:H pin solar cells deposited in a single batch process by proper passivation of the interfaces. The process consists in removing partially a deposited sacrificial oxide layer grown between the p/i or i/n interfaces by SF6 etching. This layer is an absorber of defects and impurities that are introduced in the interfaces, mainly from the chamber walls and the substrate surface. The results achieved in laboratory samples lead to devices in which the fill factor and short circuit current density were improved respectively towards 75\% and 16.5 mA cm-2, with a final working efficiency of about 9.5\%. {\textcopyright} 2001 Elsevier Science Ltd. All rights reserved.

}, doi = {10.1016/S0038-092X(01)00063-9}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034429838\&partnerID=40\&md5=7a63b536bcd3b2bbf331f4166938724c}, author = {Martins, R., A̧guas, H., Ferreira, I., Fortunato, E., Guimares, L.} } @article {Grey2016, title = {Transistors: Solid State Electrochemical WO3 Transistors with High Current Modulation (Adv. Electron. Mater. 9/2016)}, journal = {Advanced Electronic Materials}, volume = {2}, number = {9}, year = {2016}, note = {

cited By 0

}, abstract = {n/a}, doi = {10.1002/aelm.201670049}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987784661\&partnerID=40\&md5=c7a8f6a1ec7cbb3011ea49301602eafb}, author = {Grey, P., Pereira, L., Pereira, S., Barquinha, P., Cunha, I., Martins, R., Fortunato, E.} } @article {Bahubalindruni20131001, title = {Transparent current mirrors with a-GIZO TFTs: Neural modeling, simulation and fabrication}, journal = {IEEE/OSA Journal of Display Technology}, volume = {9}, number = {12}, year = {2013}, note = {

cited By 8

}, pages = {1001-1006}, abstract = {

This paper characterizes transparent current mirrors with n-type amorphous gallium-indium-zinc-oxide (a-GIZO) thin-film transistors (TFTs). Two-TFT current mirrors with different mirroring ratios and a cascode topology are considered. A neural model is developed based on the measured data of the TFTs and is implemented in Verilog-A; then it is used to simulate the circuits with Cadence Virtuoso Spectre simulator. The simulation outcomes are validated with the fabricated circuit response. These results show that the neural network can model TFT accurately, as well as the current mirroring ability of the TFTs. {\textcopyright} 2005-2012 IEEE.

}, doi = {10.1109/JDT.2013.2275251}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84889249164\&partnerID=40\&md5=3b8e0243cc3de73d5ad318c02c8677d4}, author = {Bahubalindruni, P.G.a , Tavares, V.G.a , Barquinha, P.b , Duarte, C.a , De Oliveira, P.G.a , Martins, R.b , Fortunato, E.b} } @article {Besleaga2016270, title = {Transparent field-effect transistors based on AlN-gate dielectric and IGZO-channel semiconductor}, journal = {Applied Surface Science}, volume = {379}, year = {2016}, note = {

cited By 0

}, pages = {270-276}, abstract = {

The degradation of thin-film transistors (TFTs) caused by the self-heating effect constitutes a problem to be solved for the next generation of displays. Aluminum nitride (AlN) is a viable alternative for gate dielectric of TFTs due to its good thermal conductivity, matching coefficient of thermal expansion to indium-gallium-zinc-oxide, and excellent stability at high temperatures. Here, AlN thin films of different thicknesses were fabricated by a low temperature reactive radio-frequency magnetron sputtering process, using a low cost, metallic Al target. Their electrical properties have been thoroughly assessed. Furthermore, the 200 nm and 500 nm thick AlN layers have been integrated as gate-dielectric in transparent TFTs with indium-gallium-zinc-oxide as channel semiconductor. Our study emphasizes the potential of AlN thin films for transparent electronics, whilst the functionality of the fabricated field-effect transistors is explored and discussed. {\textcopyright} 2016 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.apsusc.2016.04.083}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964546688\&partnerID=40\&md5=2a508792d318a14568f54d2b4e02fa2f}, author = {Besleaga, C.a , Stan, G.E.a , Pintilie, I.a , Barquinha, P.b , Fortunato, E.b , Martins, R.b} } @article {Fortunato2010, title = {Transparent p-type SnOx thin film transistors produced by reactive rf magnetron sputtering followed by low temperature annealing}, journal = {Applied Physics Letters}, volume = {97}, number = {5}, year = {2010}, note = {

cited By 79

}, abstract = {

P-type thin-film transistors (TFTs) using room temperature sputtered SnOx (x\<2) as a transparent oxide semiconductor have been produced. The SnOx films show p-type conduction presenting a polycrystalline structure composed with a mixture of tetragonal Β-Sn and α -SnOx phases, after annealing at 200 {\textdegree}C. These films exhibit a hole carrier concentration in the range of ≈ 1016 - 1018 cm-3; electrical resistivity between 101 - 102 cm; Hall mobility around 4.8 cm2 /V s; optical band gap of 2.8 eV; and average transmittance ≈85\% (400 to 2000 nm). The bottom gate p-type SnOx TFTs present a field-effect mobility above 1 cm2 /V s and an ON/OFF modulation ratio of 103. {\textcopyright} 2010 American Institute of Physics.

}, doi = {10.1063/1.3469939}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955724774\&partnerID=40\&md5=cbb661d999c61eb5f039d93c58777d5d}, author = {Fortunato, E.a , Barros, R.a b , Barquinha, P.a , Figueiredo, V.a , Park, S.-H.K.c , Hwang, C.-S.c , Martins, R.a} } @article {Fortunato2002247, title = {Transparent, conductive ZnO:Al thin film deposited on polymer substrates by RF magnetron sputtering}, journal = {Surface and Coatings Technology}, volume = {151-152}, year = {2002}, note = {

cited By 49

}, pages = {247-251}, abstract = {

In this paper, we present the optical, electrical, structural and mechanical properties exhibited by aluminum-doped zinc oxide (ZnO:Al) thin films produced by RF magnetron sputtering on polymeric substrates (polyethylene terephthalate, PET; Mylar type D from Dupont{\textregistered}) with a standard thickness of 100 μm. The influence of the uniaxial tensile strain on the electrical resistance of these films was evaluated in situ for the first time during tensile elongation. In addition, the role of the thickness on the mechanical behavior of the films was also evaluated. The preliminary results reveal that the increase in electrical resistance is related to the number of cracks, as well as the crack width, which also depends on the film thickness. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, doi = {10.1016/S0257-8972(01)01660-7}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-8344229317\&partnerID=40\&md5=7af938a84d7352b2d306536eefb0adbb}, author = {Fortunato, E.a , Nunes, P.a , Marques, A.a , Costa, D.a , {\'A}guas, H.a , Ferreira, I.a , Costa, M.E.V.b , Godinho, M.H.a , Almeida} } @article {Martins2005, title = {Transport in high mobility amorphous wide band gap indium zinc oxide films}, journal = {Physica Status Solidi (A) Applications and Materials Science}, volume = {202}, number = {9}, year = {2005}, note = {

cited By 71

}, pages = {R95-R97}, abstract = {

This paper discusses the electron transport in the n-type amorphous indium-zinc-oxygen system produced at room temperature by rf magnetron sputtering, under different oxygen partial pressures. The data show that the transport is not band tail limited, as it happens in conventional disordered semiconductors, but highly dependent on its ionicity, which explains the very high mobilities (>= 60 cm 2 V -1 s -1) achieved. The room temperature dependence of the Hall mobility on the carrier concentration presents a reverse behaviour than the one observed in conventional crystalline/polycrystalline semiconductors, explained mainly by the presence of charged structural defects in excess of 4 {\texttimes} 10 10 cm -2 that scatter the electrons that pass through them. {\textcopyright} 2005 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/pssa.200521020}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-25444495236\&partnerID=40\&md5=165e5409e471b9da1daf5ae0b0ea6d1d}, author = {Martins, R., Barquinha, P., Pimentel, A., Pereira, L., Fortunato, E.} } @article {Martins1989486, title = {Transport in μc-Six:Cy:Oz:H films prepared by a TCDDC system}, journal = {Journal of Non-Crystalline Solids}, volume = {114}, number = {PART 2}, year = {1989}, note = {

cited By 11

}, pages = {486-488}, abstract = {

N- and p-type weakly absorbing and highly conductive microcrystalline thin μc-Six:Cy:Oz:H films, have been produced by a TCDDC (Two Consecutive Decomposition and Deposition Chamber) system1. The optoelectronic and structural results show that we are in the presence of a mixed phase of Si microcrystals (c-islands) embedded in a-Six:Cy:Oz:H (a-tissue). Based on that, we propose a model where transport mechanisms are explained by the potential fluctuations related to films heterogeneities. Thus, conduction is due to carriers that by tunneling or percolation "pass" or "go" trough the barriers and/or percolate randomly by the formed channels. {\textcopyright} 1989.

}, doi = {10.1016/0022-3093(89)90625-X}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024837634\&partnerID=40\&md5=d26c6c88b4ee39a0d3038f18b215022b}, author = {Martins, R.a , Willeke, G.b , Fortunato, E.a , Ferreira, I.a , Vieira, M.a , Santos, M.a , Ma{\c c}arico, A.a , Guimar{\~a}es, L.a} } @article {Fantoni19991709, title = {Transport properties in microcrystalline silicon solar cells under AM1.5 illumination analyzed by two-dimensional numerical simulation}, journal = {Solid-State Electronics}, volume = {43}, number = {9}, year = {1999}, note = {

cited By 4

}, pages = {1709-1714}, abstract = {

Microcrystalline silicon is a two-phase material. Its composition can be interpreted as a series of grains of crystalline silicon imbedded in an amorphous silicon tissue, with a high concentration of dangling bonds in the transition regions. In this paper, results for the transport properties of a μc-Si:H p-i-n junction obtained by means of two-dimensional numerical simulation are reported. The role played by the boundary regions between the crystalline grains and the amorphous matrix is taken into account and these regions are treated similar to a heterojunction interface. The device is analyzed under AM1.5 illumination and the paper outlines the influence of the local electric field at the grain boundary transition regions on the internal electric configuration of the device and on the transport mechanism within the μc-Si:H intrinsic layer.

}, doi = {10.1016/S0038-1101(99)00139-2}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033185603\&partnerID=40\&md5=1aab2b1f713983e2eccc5c6b7e7cec06}, author = {Fantoni, A.a , Vieira, M.b , Martins, R.a} } @article {Martins1996493, title = {Transport properties of doped silicon oxycarbide microcrystalline films produced by spatial separation techniques}, journal = {Solar Energy Materials and Solar Cells}, volume = {41-42}, year = {1996}, note = {

cited By 3

}, pages = {493-517}, abstract = {

This paper presents results of the role of the oxygen partial pressure used during the deposition process on the transport properties exhibited by doped microcrystalline silicon oxycarbide films produced by a Two Consecutive Decomposition and Deposition Chamber system, where a spatial separation between the plasma and the growth regions is achieved. This paper also presents the interpretative models of the optoelectronic behaviour observed in these films (highly conductive and transparent with suitable properties for optoelectronic applications) as well as the interpretation of the growth process that leads to film{\textquoteright}s microcrystallization.

}, doi = {10.1016/0927-0248(95)00096-8}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030173265\&partnerID=40\&md5=1a2ad13ec8eda6bf8f3eac5d004598dd}, author = {Martins, R.a , Vieira, M.b , Ferreira, I.a , Fortunato, E.a , Guimar{\~a}es, L.a} } @article {Fantoni1999109, title = {Transport properties of μc-Si:H analyzed by means of numerical simulation}, journal = {Thin Solid Films}, volume = {337}, number = {1-2}, year = {1999}, note = {

cited By 2

}, pages = {109-112}, abstract = {

Microcrystalline silicon is a two-phase material. Its composition can be interpreted as grains of crystalline silicon imbedded in an amorphous silicon tissue, with a high concentration of danglind bonds in the transition regions. In this paper, results obtained by means of numerical simulations about the transport properties of a μc-Si:H p-i-n junction are reported. The role played by the boundary regions between the crystalline grains and the amorphous matrix is taken in account, and these regions are treated similarly to a heterojunction interface. The influence of the local electric field at the grains boundary transition regions on the internal electric configuration of the device is outlined under illumination and applied external bias. {\textcopyright} 1999 Elsevier Science S.A. All rights reserved.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0346206471\&partnerID=40\&md5=9e8c7647f5378f6c1bf1d2365e46788c}, author = {Fantoni, A.a , Vieira, M.b , Martins, R.a} } @article {Fortunato1989120, title = {Tunneling in vertical μcSi/aSixCyOz:H/μcSi heterostructures}, journal = {Journal of Non-Crystalline Solids}, volume = {115}, number = {1-3}, year = {1989}, note = {

cited By 23

}, pages = {120-122}, abstract = {

In this paper we report by the first time tunneling tranport on vertical μcSi/aSixCyOz:H/μcSi (μcaμc) heterostructures produced in a Two consecutive Decomposition and Deposition Chamber system where a Negative Differential Conductance is observed even at room temperature. Giant bias anomalies are observed, that decrease with temperature. Tunneling spectroscopy data are also reported for samples measured at low temperatures. A qualitative information of the recorded data is obtained and related with main features of the heterostructure. Nevertheless in this stage is hard to take quantitative information. {\textcopyright} 1989.

}, doi = {10.1016/0022-3093(89)90380-3}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0024780126\&partnerID=40\&md5=959bda89683f08ae6554fb9668d55d98}, author = {Fortunato, E., Martins, R., Ferreira, I., Santos, M., Ma{\c c}arico, A., Guimar{\~a}es, L.} } @article {Fantoni19963154, title = {A two-dimensional numerical simulation of a non-uniformly illuminated amorphous silicon solar cell}, journal = {Journal of Physics D: Applied Physics}, volume = {29}, number = {12}, year = {1996}, note = {

cited By 16

}, pages = {3154-3159}, abstract = {

We present here a two-dimensional numerical simulation of a hydrogenated amorphous silicon p-i-n solar cell non-uniformly illuminated through the p-layer. This simulation is used to show the effect of the presence of dark regions in the illuminated surface on the electrical behaviour of the device. The continuity equations for holes and electrons together with Poisson{\textquoteright}s equation, implemented with a recombination mechanism reflecting the amorphous structure of the material, are solved using standard numerical techniques over a rectangular domain. The results obtained reveal the appearance of a lateral component of the electric field and current density vectors inside the structure. The effect of such components is a lateral carrier flow of electrons inside the intrinsic layer and of holes inside the p-layer, resulting in leakage of the transverse current collected at the contacts and an increase in the series resistance.

}, doi = {10.1088/0022-3727/29/12/033}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0030414535\&partnerID=40\&md5=b0e9bb0fba3f294261f35823ac24e482}, author = {Fantoni, A.a , Vieira, M.a , Cruz, J.a , Schwarz, R.b , Martins, R.a} } @article {Ferreira1998140, title = {Undoped and doped crystalline silicon films obtained by Nd-YAG laser}, journal = {Thin Solid Films}, volume = {317}, number = {1-2}, year = {1998}, note = {

cited By 6

}, pages = {140-143}, abstract = {

In this paper, we present results of the role of laser beam energy and shot density on the electro-optical and structural properties of undoped and doped recrystallized amorphous silicon thin films, generated by pulsed Nd-YAG laser (λ = 532 nm). The data reveal that the structure and electrical characteristics of the recrystallized thin films are mainly dependent on the energy and shot density of the laser beam, while the morphology of the obtained films are mainly governed by the number of shots used. The data also show that the electrical conductivity of undoped and doped recrystallized films can be varied up to 6 orders of magnitude, by the proper choice of the recrystallization conditions. Doped samples with conductivities in the amorphous states in the range of 10-5 Ω-1 cm-1 present, after recrystallization, conductivities of about 300 Ω-1 cm-1. The SEM micro-chemical analysis also shows that the obtained crystalline grains are constituted by pure silicon. {\textcopyright} 1998 Elsevier Science S.A.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032049889\&partnerID=40\&md5=f276fd93d6911a0ebaf44d554e1f3ca8}, author = {Ferreira, I., Carvalho, J., Martins, R.} } @article {Danciu20136701, title = {Uniform arrays of ZnO 1D nanostructures grown on Al:ZnO seeds layers by hydrothermal method}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {13}, number = {10}, year = {2013}, note = {

cited By 3

}, pages = {6701-6710}, abstract = {

In obtaining uniform array of ZnO 1D nanostructures, especially using solution based methods, the thickness and the morphology of the epitaxial seeds layer are very important. The paper presents the effect of the thickness and the morphology of the Al:ZnO seeds layer on the morphology and properties of ZnO nanowires array grown by hydrothermal method. Compact and vertically aligned ZnO 1D nanostructures were obtained. Concentration of 0.02 M of zinc nitrate was found to be optimal for growing nanowires with diameters up to 50 nm and lengths between 1.5 and 2.5 microns. Using 0.04 M solution, nanorods with diameter between 50 and 100 nm were obtained. The correlation between the crystal structure and optical properties of ZnO nanowires is discussed. From electrical measurements on single nanowire, resistivity value of 9{\texttimes}10?2 cm was obtained. The I-V curves of single ZnO NWs show quasi diode characteristic when an e-beam is irradiating the NWs, and a typical semiconductive behaviour when the e-beam is turned off. Copyright {\textcopyright} 2013 American Scientific Publishers.

}, doi = {10.1166/jnn.2013.7773}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84888996811\&partnerID=40\&md5=56611a318b32c5fc6060f541cb67d134}, author = {Danciu, A.-I..a b , Musat, V.a , Busani, T.b , Pinto, J.V.b , Barros, R.b , Maria Rego, A.c , Maria Ferraria, A.c , Carvalho, P.} } @article {Gon{\c c}alves20061444, title = {UV and ozone influence on the conductivity of ZnO thin films}, journal = {Journal of Non-Crystalline Solids}, volume = {352}, number = {9-20 SPEC. ISS.}, year = {2006}, note = {

cited By 20

}, pages = {1444-1447}, abstract = {

Complex impedance measurements were used to analyze the influence of ultraviolet and ozone gas on the electronic behaviour of ZnO films grown by rf magnetron sputtering. The data show that UV exposure strongly increases the ac conductivity of the film at very low frequencies, and that after ozone exposure it recovers the original value. At high frequencies, however, UV-light exposure it does not change the conductivity but the ozone acts in the sense to decrease it. Two distinct mechanisms, related to two relaxation time distributions are clearly observed: they are superimposed in the virgin sample, but they split forming two semicircles in the z"(f) - z'(f) diagrams when the samples are treated with UV and/or ozone gas. A combination of the bruggeman effective medium approximation (BEMA) with the random free energy barrier model is used to fit the data and to explain the ac conductivity variation phenomena observed. {\textcopyright} 2006 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.jnoncrysol.2006.02.021}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33744532746\&partnerID=40\&md5=693ea91c83ffbf919424c34de4fa9d34}, author = {Gon{\c c}alves, G.a , Pimentel, A.a , Fortunato, E.a , Martins, R.a , Queiroz, E.L.b , Bianchi, R.F.b c , Faria, R.M.b} } @article {Malik19971425, title = {UV enhanced and solar blind photodetectors based on large-band-gap materials}, journal = {Materials Science Forum}, volume = {258-263}, number = {9993}, year = {1997}, note = {

cited By 1

}, pages = {1425-1430}, abstract = {

High quantum efficiency, UV-enhanced monocrystalline zinc sulphide optical sensors for precise radiometric and spectroscopic measurements have been developed by spray deposition of heavy fluorinedoped tin oxide thin films with carrier concentration near 1021 cm-3 onto the surface of zinc sulphide monocrystals as an alternative to the UV-enhanced silicon photodetectors as well as to new detectors based on SiC and GaN. The fabricated sensors have an unbiased internal quantum efficiency that was nearly 100\% from 250 to 320 nm, and the typical sensitivity at 290 nm is 0.15 A/W. The sensors were insensitive to solar radiation in earth{\textquoteright}s conditions and can be used as solar blind photodetectors for precision UV-measurements under direct solar illumination, both terrestrial and space applications.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0031339551\&partnerID=40\&md5=a9b74e54af21e69bbe281a13c57bca43}, author = {Malik, A., Martins, R.} } @article {Liu2015S75, title = {A water-induced high-k yttrium oxide dielectric for fully-solution-processed oxide thin-film transistors}, journal = {Current Applied Physics}, volume = {15}, year = {2015}, note = {

cited By 0

}, pages = {S75-S81}, abstract = {

In this work, we develop a simple and eco-friendly water-inducement method for high-k yttrium oxide (YOx) dielectric. To prepare YOx thin films at low temperature, yttrium nitrate and deionized water were used as the source materials. No toxic organic materials were required in the YOx coating process. The YOx thin film annealed at 350 {\textdegree}C showed a low leakage current density of 2 {\texttimes} 10-9 A/cm2 at 5 MV/cm and a large areal-capacitance of 448 nF/cm2 at 1 kHz. On the basis of its implementation as the gate dielectric, the fully-water-induced In2O3 TFT based on YOx exhibited a high field-effect mobility of 15.98 cm2/Vs, excellent subthreshold swing of 75 mV/dec, an on/off current ratio of 6 {\texttimes} 106, and a negligible hysteresis of 50 mV. The as-fabricated TFT operated at a low voltage (\~{}1.5 V) and showed high drain current drive capability, enabling oxide TFT with a water-induced high-k dielectric for use in backplane electronics for low-power mobile display applications. {\textcopyright} 2015 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.cap.2015.04.015}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84942369470\&partnerID=40\&md5=7ddc20cb4ad05fcafb6977a61be52dbc}, author = {Liu, A.a , Liu, G.a , Zhu, H.a , Meng, Y.a , Song, H.a , Shin, B.b , Fortunato, E.c , Martins, R.c , Shan, F.a} } @article {Fortunato2011336, title = {Where science fiction meets reality? With oxide semiconductors!}, journal = {Physica Status Solidi - Rapid Research Letters}, volume = {5}, number = {9}, year = {2011}, note = {

cited By 30

}, pages = {336-339}, abstract = {

Transparent electronics is today one of the most advanced topics for a wide range of device applications, where the key components are wide band gap semiconductors, where oxides of different origin play an important role, not only as passive components but also as active components similar to what we observe in conventional semiconductors. As passive components they include the use of these materials as dielectrics for a wide range of electronic devices and also as transparent electrical conductors for use in several optoelectronic applications, such as liquid crystal displays, organic light emitting diodes, solar cells, optical sensors etc. As active materials, they exploit the use of truly electronic semiconductors where the main emphasis is being put on transparent thin film transistors, light emitting diodes, lasers, ultraviolet sensors and integrated circuits among others. {\textcopyright} 2011 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim.

}, doi = {10.1002/pssr.201105246}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-80052303120\&partnerID=40\&md5=5938816c6f935173d6a0d10e478668f5}, author = {Fortunato, E., Martins, R.} } @article {Fortunato20042541, title = {Wide-bandgap high-mobility ZnO thin-film transistors produced at room temperature}, journal = {Applied Physics Letters}, volume = {85}, number = {13}, year = {2004}, note = {

cited By 415

}, pages = {2541-2543}, abstract = {

The fabrication of high field-effect mobility ZnO thin film transistor (ZnO-TFT) at room temperature by rf magnetron sputtering was discussed. The ZnO used was deposited onto borosilicate glass substrate with a thickness of 1 mm with 100 x 100 mm surface area, coated with a 200 nm sputtered ITO film. The hall mobilities of about 2 cm2 / V s and a carrier concentration of 3 x 1016cm-3 were measured for the films with lower resistivity. It was observed that the ZnO-TFT presented an average optical transmission of 80\% in the visibility part of the spectrum.

}, doi = {10.1063/1.1790587}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-7544247006\&partnerID=40\&md5=0c41fa8d326951414a9024ea10e40029}, author = {Fortunato, E.M.C., Barquinha, P.M.C., Pimentel, A.C.M.B.G., Gon{\c c}alves, A.M.F., Marques, A.J.S., Martins, R.F.P., Pereira, L.M.N.} } @article {Martins2008, title = {Write-erase and read paper memory transistor}, journal = {Applied Physics Letters}, volume = {93}, number = {20}, year = {2008}, note = {

cited By 59

}, abstract = {

We report the architecture and the performances of a memory based on a single field-effect transistor built on paper able to write-erase and read. The device is composed of natural multilayer cellulose fibers that simultaneously act as structural support and gate dielectric; active and passive multicomponent amorphous oxides that work as the channel and gate electrode layers, respectively, complemented by the use of patterned metal layers as source/drain electrodes. The devices exhibit a large counterclockwise hysteresis associated with the memory effect, with a turn-on voltage shift between 1 and -14.5 V, on/off ratio and saturation mobilities of about 104 and 40 cm 2 V-1 s-1, respectively, and estimated charge retention times above 14 000 h. {\textcopyright} 2008 American Institute of Physics.

}, doi = {10.1063/1.3030873}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-56849108223\&partnerID=40\&md5=71a735e4bcafc24b7081c29ed155f599}, author = {Martins, R., Barquinha, P., Pereira, L., Correia, N., Gonalves, G., Ferreira, I., Fortunato, E.} } @article {Nayak2010, title = {Zinc concentration dependence study of solution processed amorphous indium gallium zinc oxide thin film transistors using high-k dielectric}, journal = {Applied Physics Letters}, volume = {97}, number = {18}, year = {2010}, note = {

cited By 35

}, abstract = {

The effects of zinc concentration on the performance of solution processed amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFTs) have been investigated using high-k aluminum titanium oxide as gate dielectric. The x-ray diffraction results confirmed that all the IGZO channel layers are amorphous. The performance of a-IGZO TFTs were investigated in the linear regime operation. Highest linear field-effect mobility of 5.8 cm2 /V s with an Ion / Ioff ratio of 6{\texttimes} 107 and subthreshold swing of 0.28 V/dec were obtained for the a-IGZO (311) TFTs. The obtained performance of the a-IGZO TFTs is very promising for low-voltage display applications. {\textcopyright} 2010 American Institute of Physics.

}, doi = {10.1063/1.3514249}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-78649237787\&partnerID=40\&md5=d12b792241977ee232bbd55381319ee2}, author = {Nayak, P.K.a , Busani, T.a , Elamurugu, E.a , Barquinha, P.a , Martins, R.a , Hong, Y.b , Fortunato, E.a} } @article {Martins20041398, title = {Zinc oxide as an ozone sensor}, journal = {Journal of Applied Physics}, volume = {96}, number = {3}, year = {2004}, note = {

cited By 161

}, pages = {1398-1408}, abstract = {

A study of intrinsic zinc oxide thin film as ozone sensor based on the ultraviolet (UV) photoreduction and subsequent ozone re oxidation of zinc oxide as a fully reversible process was presented. It was found that the film described were produced by spray pyrolysis, dc and rf magnetron sputtering. The dc resistivity of the films changed more than eight orders of magnitude when exposed to an UV dose of 4 mW/cm2. Analysis shows that the porous and textured zinc oxide films produced by spray pyrolysis at low substrate exhibit an excellent ac impedance response.

}, doi = {10.1063/1.1765864}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-4143149691\&partnerID=40\&md5=919bc88728d4444b4959a05cf7182a2d}, author = {Martins, R.a , Fortunato, E.a , Nunes, P.a , Ferreira, I.a , Marques, A.a , Bender, M.b , Katsarakis, N.c , Cimalla, V.c , Kiria} } @article {O{\textquoteright}Brien20104515, title = {Zinc oxide thin films: Characterization and potential applications}, journal = {Thin Solid Films}, volume = {518}, number = {16}, year = {2010}, note = {

cited By 37

}, pages = {4515-4519}, abstract = {

Zinc oxide (ZnO) has attracted recent interest for a range of applications, including use as a transparent conductive oxide (TCO) and in gas sensor devices. This paper compares ZnO films grown using two methods designed for the production of thin films, namely sol-gel and aerosol assisted chemical vapour deposition (AACVD) for potential use in sensor and TCO applications. Materials produced by the sol-gel route were observed to be amorphous when annealed at 350 {\textdegree}C, but were crystalline when annealed at higher temperatures and had a relatively open grain structure when compared to the AACVD films. Electrical characterization showed that materials were highly resistive, but that their properties varied considerably when the measurements were performed in vacuum or in air. This behaviour was rapidly reversible and reproducible for room temperature measurement. In contrast materials grown by aerosol-assisted CVD were non-porous, polycrystalline and conductive. Measured electrical properties did not vary with changing measurement atmosphere. These differences are discussed in terms of the structural characterisation of the films and some comments are made regarding the suitability of both approaches for the growth of ZnO thin film sensor materials. {\textcopyright} 2009 Elsevier B.V. All rights reserved.

}, doi = {10.1016/j.tsf.2009.12.020}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955643143\&partnerID=40\&md5=8421fa714fc3e7a4b5934e61854f8593}, author = {O{\textquoteright}Brien, S.a , Nolan, M.G.a , {\c C}opuroglu, M.a , Hamilton, J.A.a , Povey, I.a , Pereira, L.b , Martins, R.b , Fortunato, E.b , Pem} } @article {Fortunato2009197, title = {Zinc oxide, a multifunctional material: From material to device applications}, journal = {Applied Physics A: Materials Science and Processing}, volume = {96}, number = {1}, year = {2009}, note = {

cited By 75

}, pages = {197-205}, abstract = {

In this paper we report on some of the recent advances in transparent thin film oxide semiconductors, specifically zinc oxide produced by radio frequency magnetron sputtering at room temperature, with multifunctional properties. By controlling the deposition parameters it is possible to produce undoped material with electronic semiconductor properties, or by doping it to get either n-type or p-type semiconductor behavior. In this work we refer to our experience in producing n-type doped zinc oxide as transparent electrode to be used in optoelectronic applications such as solar cells and position sensitive detectors, while the undoped zinc oxide can be used as active layer of fully transparent thin film transistors. {\textcopyright} 2009 Springer-Verlag.

}, doi = {10.1007/s00339-009-5086-5}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67349213281\&partnerID=40\&md5=77a3947bfe2712c237d1722700c32a40}, author = {Fortunato, E., Gon{\c c}alves, A., Pimentel, A., Barquinha, P., Gon{\c c}alves, G., Pereira, L., Ferreira, I., Martins, R.} } @article {Fortunato200412, title = {ZnO:Ga thin films produced by RF sputtering at room temperature: Effect of the power density}, journal = {Materials Science Forum}, volume = {455-456}, year = {2004}, note = {

cited By 4

}, pages = {12-15}, abstract = {

Ga-doped polycrystalline zinc oxide (GZO) thin films have been deposited at high growth rates by rf magnetron sputtering. The dependence of electrical, optical and morphological properties on the rf power density were investigated. The lowest resistivity of 1.9{\texttimes}10-4 Ωcm was obtained for a rf power density of 9 W/cm2 and an argon sputtering pressure of 0.15 Pa at room temperature. The films are polycrystalline with a hexagonal structure and a strong crystallographic c-axis orientation (002) perpendicular to the substrate surface. The films present an overall transmittance in the visible spectra of about 85\%. The low resistivity, accomplished with a high growth rate deposited at room temperature, enables the deposition of these films onto polymeric substrates for flexible optoelectronic devices and displays.

}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-3142674243\&partnerID=40\&md5=bbe3b4e7a763f097056a1711000d5067}, author = {Fortunato, E., Assun{\c c}{\~a}o, V., Marques, A., Gon{\c c}alves, A., {\'A}guas, H., Pereira, L., Ferreira, I., Fernandes, F.M.B., Silva, R.J.C.,} }