Publications

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Submitted
Branquinho, Rita, Daniela Salgueiro, Lidia Santos, Pedro Barquinha, Luis Pereira, Rodrigo Martins, and Elvira Fortunato. "{Aqueous Combustion Synthesis of Aluminum Oxide Thin Films and Application as Gate Dielectric in GZTO Solution-Based TFTs}." {ACS APPLIED MATERIALS & INTERFACES}. {6} (Submitted): {19592-19599}. Abstract

{Solution processing has been recently considered as an option when trying to reduce the costs associated with deposition under vacuum. In this context, most of the research efforts have been centered in the development of the semiconductors processes nevertheless the development of the most suitable dielectrics for oxide based transistors is as relevant as the semiconductor layer itself. In this work we explore the solution combustion synthesis and report on a completely new and green route for the preparation of amorphous aluminum oxide thin films; introducing water as solvent. Optimized dielectric layers were obtained for a water based precursor solution with 0.1 M concentration and demonstrated high capacitance, 625 nF cm(-2) at 10 kHz, and a permittivity of 7.1. These thin films were successfully applied as gate dielectric in solution processed gallium-zinc-tin oxide (GZTO) thin film transistors (TFTs) yielding good electrical performance such as subthreshold slope of about 0.3 V dec(-1) and mobility above 1.3 cm(2) V-1 s(-1).}

Santos, Lidia, Joana P. Neto, Ana Crespo, Daniela Nunes, Nuno Costa, Isabel M. Fonseca, Pedro Barquinha, Luis Pereira, Jorge Silva, Rodrigo Martins, and Elvira Fortunato. "{WO3 Nanoparticle-Based Conformable pH Sensor}." {ACS APPLIED MATERIALS & INTERFACES}. {6} (Submitted): {12226-12234}. Abstract

{pH is a vital physiological parameter that can be used for disease diagnosis and treatment as well as in monitoring other biological processes. Metal/metal oxide based pH sensors have several advantages regarding their reliability, miniaturization, and cost-effectiveness, which are critical characteristics for in vivo applications. In this work, WO3 nanoparticles were electrodeposited on flexible substrates over metal electrodes with a sensing area of 1 mm(2). These sensors show a sensitivity of -56.7 +/- 1.3 mV/pH, in a wide pH range of 9 to 5. A proof of concept is also demonstrated using a flexible reference electrode in solid electrolyte with a curved surface. A good balance between the performance parameters (sensitivity), the production costs, and simplicity of the sensors was accomplished, as required for wearable biomedical devices.}

Zanarini, Simone, Nadia Garino, Jijeesh Ravi Nair, Carlotta Francia, Pawel Jerzy Wojcik, Luis Pereira, Elvira Fortunato, Rodrigo Martins, Silvia Bodoardo, and Nerino Penazzi. "{Contrast Enhancement in Polymeric Electrochromic Devices Encompassing Room Temperature Ionic Liquids}." {INTERNATIONAL JOURNAL OF ELECTROCHEMICAL SCIENCE}. {9} (Submitted): {1650-1662}. Abstract

{We report the preparation and spectro-electrochemical characterization of electrochromic devices (ECD) combining inkjet-printed WO3 as cathode and electro-deposited V2O5 as anode. ECD were prepared for the first time with an optimized formulation of gel polymer electrolyte based on Bisphenol A ethoxylate dimethacrylate and Poly(ethylene glycol) methyl ether methacrylate (BEMA/PEGMA) encompassing the Room Temperature Ionic Liquid (RTIL, 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) as solvent. The UV-VIS spectrum of ECD was recorded at different potentials during Li+ insertion and de-insertion; additionally the Percent Trasmittance (T%) of ECD vs. time was investigated during repeated bleaching and coloring cycles allowing thus the estimation of switching times and device stability. Due to the lower ionic conductivity and the apparent superior solvent permeability within WO3 active layer, RTIL containing ECD showed slower switching times, but higher contrast with respect to the similar ones with EC/DEC as solvent. These results indicate that the ECD containing environment-friendly RTIL electrolytes are suitable for applications requiring high contrast, high safety and moderately fast switching times.}

Schmeisser, Dieter, Joerg Haeberle, Pedro Barquinha, Diana Gaspar, Luis Pereira, Rodrigo Martins, and Elvira Fortunato. "{Electronic structure of amorphous ZnO films}." {PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 11, NO 9-10}. Eds. M. {Godlewski, and A. } Zakrzewski. Vol. {11}. {Physica Status Solidi C-Current Topics in Solid State Physics}, {11}. Submitted. {1476-1480}. Abstract

{We use resonant photoemission spectroscopy (resPES) to study the electronic properties of amorphous ZnO (a-ZnO) layers. We report on the core levels, the valence band (VB) PES data, and the X-ray absorption (XAS) data which we use for the conduction band (CB) density of states. From these results we are able to derive the partial density of states (pDOS) of O2p and Zn4s4p states in the VB and CB, respectively as well as a band scheme. At the O1s resonance we observe a band of localized defect states which is located between the Fermi energy and the CBM. At the Zn2p edge the XAS data indicate that localized Zn4s4p states are involved in the DOS starting already at the Fermi energy. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim}

2013
Nandy, Suman, Gonçalo Gonçalves, Joana Vaz Pinto, Tito Busani, Vitor Figueiredo, Lu\'ıs Pereira, Rodrigo Ferrão {Paiva Martins}, and Elvira Fortunato. "{Current transport mechanism at metal-semiconductor nanoscale interfaces based on ultrahigh density arrays of p-type NiO nano-pillars.}." Nanoscale. 5 (2013): 11699-709. AbstractWebsite

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'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.

Parthiban, Shanmugam, Elamurugu Elangovan, Pradipta K. Nayak, Alexandra Gonçalves, Daniela Nunes, Lu\'ıs Pereira, Pedro Barquinha, Tito Busani, Elvira Fortunato, and Rodrigo Martins. "{Performances of Microcrystalline Zinc Tin Oxide Thin-Film Transistors Processed by Spray Pyrolysis}." 9 (2013): 825-831. Abstract
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Branquinho, Rita, Joana V. Pinto, Tito Busani, Pedro Barquinha, Luis Pereira, Pedro Viana Baptista, Rodrigo Martins, and Elvira Fortunato. "{Plastic Compatible Sputtered Ta O Sensitive Layer for Oxide Semiconductor TFT Sensors}." 9 (2013): 723-728. Abstract
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a.M. Ramos, S. Pereira, M. T. Cidade, G. Pereira, R. Branquinho, L. Pereira, R. Martins, and E. Fortunato. "{Preparation and characterization of cellulose nanocomposite hydrogels as functional electrolytes}." Solid State Ionics. 242 (2013): 26-32. AbstractWebsite
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2012
Pereira, Lu\'ıs, Pedro Barquinha, Gonçalo Gonçalves, Elvira Fortunato, and Rodrigo Martins. "{Multicomponent dielectrics for oxide TFT}." Eds. Ferechteh H. Teherani, David C. Look, and David J. Rogers. Vol. 8263. 2012. 826316–16. Abstract
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Martins, R., V. Figueiredo, R. Barros, P. Barquinha, G. Gonçalves, L. Pereira, I. Ferreira, and E. Fortunato. "{P-type oxide-based thin film transistors produced at low temperatures}." Eds. Ferechteh H. Teherani, David C. Look, and David J. Rogers. Vol. 8263. 2012. 826315–15. Abstract
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Baquinha, Pedro, Rodrigo Martins, Luis Pereira, and Elvira Fortunato Transparent Oxide Electronics. Wiley, 2012.
2011
Martins, Rodrigo, Arokia Nathan, Raquel Barros, Lu\'ıs Pereira, Pedro Barquinha, Nuno Correia, Ricardo Costa, Arman Ahnood, Isabel Ferreira, and Elvira Fortunato. "{Complementary metal oxide semiconductor technology with and on paper.}." Advanced materials (Deerfield Beach, Fla.). 23 (2011): 4491-6. AbstractWebsite
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Nolan, M. G., J. A. Hamilton, S. O’Brien, G. Bruno, L. Pereira, E. Fortunato, R. Martins, I. M. Povey, and M. E. Pemble. "{The characterisation of aerosol assisted CVD conducting, photocatalytic indium doped zinc oxide films}." Journal of Photochemistry and Photobiology A: Chemistry. 219 (2011): 10-15. AbstractWebsite
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Martins, R., B. Brás, I. Ferreira, L. Pereira, P. Barquinha, N. Correia, R. Costa, T. Busani, A. Gonçalves, A. Pimentel, and E. Fortunato. "{Away from silicon era: the paper electronics}." Eds. Ferechteh H. Teherani, David C. Look, and David J. Rogers. Vol. 7940. 2011. 79400P–10. Abstract
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Gonçalves, Gonçalo, Valentina Grasso, Pedro Barquinha, Lu\'ıs Pereira, Elangovan Elamurugu, Mauro Brignone, Rodrigo Martins, Vito Lambertini, and Elvira Fortunato. "{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}." Plasma Processes and Polymers. 8 (2011): 340-345. AbstractWebsite
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2010
Martins, R., L. Pereira, P. Barquinha, N. Correia, G. Gonçalves, I. Ferreira, C. Dias, and E. Fortunato. "{Floating gate memory paper transistor}." Eds. Ferechteh H. Teherani, David C. Look, Cole W. Litton, and David J. Rogers. Vol. 7603. 2010. 760314–11. Abstract
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Pereira, L., H. Águas, L. Gomes, P. Barquinha, E. Fortunato, and R. Martins. "{Nanostructured Silicon Based Thin Film Transistors Processed in the Plasma Dark Region}." Journal of Nanoscience and Nanotechnology. 10 (2010): 2938-2943. AbstractWebsite
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Gonçalves, G., P. Barquinha, L. Pereira, N. Franco, E. Alves, R. Martins, and E. Fortunato. "{High Mobility a-IGO Films Produced at Room Temperature and Their Application in TFTs}." Electrochemical and Solid-State Letters. 13 (2010): H20. AbstractWebsite
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Olziersky, Antonis, Pedro Barquinha, Anna Vilà, Luís Pereira, Gonçalo Gonçalves, Elvira Fortunato, Rodrigo Martins, and Juan R. Morante. "{Insight on the SU-8 resist as passivation layer for transparent Ga[sub 2]O[sub 3]–In[sub 2]O[sub 3]–ZnO thin-film transistors}." Journal of Applied Physics. 108 (2010): 064505. AbstractWebsite
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Barquinha, Pedro, Luis Pereira, Gonçalo Gonçalves, Danjela Kuscer, Marija Kosec, Anna Vilà, Antonis Olziersky, Juan Ramon Morante, Rodrigo Martins, and Elvira Fortunato. "{Low-temperature sputtered mixtures of high-$ąppa$ and high bandgap dielectrics for GIZO TFTs}." Journal of the Society for Information Display. 18 (2010): 762. AbstractWebsite
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2009
Pereira, Lu\'ıs, Pedro Barquinha, Gonçalo Gonçalves, Anna Vilà, Antonis Olziersky, Joan Morante, Elvira Fortunato, and Rodrigo Martins. "{Sputtered multicomponent amorphous dielectrics for transparent electronics}." physica status solidi (a). 206 (2009): 2149-2154. AbstractWebsite
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Fortunato, E., L. Pereira, P. Barquinha, I. Ferreira, R. Prabakaran, G. Gonçalves, A. Gonçalves, and R. Martins. "{Oxide semiconductors: Order within the disorder}." Philosophical Magazine. 89 (2009): 2741-2758. AbstractWebsite
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Bernardo, Gabriel, Gonçalo Gonçalves, Pedro Barquinha, Quirina Ferreira, Graça Brotas, Lu\'ıs Pereira, Ana Charas, Jorge Morgado, Rodrigo Martins, and Elvira Fortunato. "{Polymer light-emitting diodes with amorphous indium-zinc oxide anodes deposited at room temperature}." Synthetic Metals. 159 (2009): 1112-1115. AbstractWebsite
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Fortunato, E., A. Gonçalves, A. Pimentel, P. Barquinha, G. Gonçalves, L. Pereira, I. Ferreira, and R. Martins. "{Zinc oxide, a multifunctional material: from material to device applications}." Applied Physics A. 96 (2009): 197-205. AbstractWebsite
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Fortunato, E., Nuno Correia, Pedro Barquinha, Cláudia Costa, Lu\'ıs Pereira, Gonçalo Gonçalves, and Rodrigo Martins. "{Paper field effect transistor}." Eds. Ferechteh H. Teherani, Cole W. Litton, and David J. Rogers. Vol. 7217. 2009. 72170K–11. Abstract
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