@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 {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 {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 {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 {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 {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 {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 {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} } @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.} } @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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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.} } @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} } @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 {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 {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 {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 {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 {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 {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 {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 {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 {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} } @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 {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 {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 {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} } @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} } @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 {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 {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 {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 {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 {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 {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,} } @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.} }