Nandy, S., G. Goncalves, J. V. Pinto, T. Busani, V. Figueiredo, L. Pereira, R. F. Paiva Martins, and E. Fortunato,
"Current transport mechanism at metal-semiconductor nanoscale interfaces based on ultrahigh density arrays of p-type NiO nano-pillars",
Nanoscale, vol. 5, issue 23, pp. 11699-11709, 2013.
AbstractThe 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.
Nayak, P. K., J. V. Pinto, G. Goncalves, R. Martins, and E. Fortunato,
"Environmental, Optical, and Electrical Stability Study of Solution-Processed Zinc-Tin-Oxide Thin-Film Transistors",
Journal of Display Technology, vol. 7, issue 12, pp. 640-643, 2011.
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Nunes, D., L. Santos, P. Duarte, A. Pimentel, J. V. Pinto, P. Barquinha, P. A. Carvalho, E. Fortunato, and R. Martins,
"Room Temperature Synthesis of Cu2O Nanospheres: Optical Properties and Thermal Behavior",
Microscopy and Microanalysis, vol. 21, issue 01, pp. 11, 2015.
AbstractThe present work reports a simple and easy wet chemistry synthesis of cuprous oxide (Cu2O) nanospheres at room temperature without surfactants and using different precursors. Structural characterization was carried out by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy coupled with focused ion beam and energy-dispersive X-ray spectroscopy. The optical band gaps were determined from diffuse reflectance spectroscopy. The photoluminescence behavior of the as-synthesized nanospheres showed significant differences depending on the precursors used. The Cu2O nanospheres were constituted by aggregates of nanocrystals, in which an on/off emission behavior of each individual nanocrystal was identified during transmission electron microscopy observations. The thermal behavior of the Cu2O nanospheres was investigated with in situ X-ray diffraction and differential scanning calorimetry experiments. Remarkable structural differences were observed for the nanospheres annealed in air, which turned into hollow spherical structures surrounded by outsized nanocrystals. FAU - Nunes, Daniela
Gonçalves, A., J. Resende, A. C. Marques, J. V. Pinto, D. Nunes, A. Marie, R. Gonçalves, L. Pereira, R. Martins, and E. Fortunato,
"Smart optically active VO nanostructured layers applied in roof-type ceramic tiles for energy efficiency",
Solar Energy Materials & Solar Cells, vol. 150, pp. 1-9, 2016.
Santos, R., J. Loureiro, A. Nogueira, E. Elangovan, J. V. Pinto, J. P. Veiga, T. Busani, E. Fortunato, R. Martins, and I. Ferreira,
"Thermoelectric properties of V2O5 thin films deposited by thermal evaporation",
Applied Surface Science, vol. 282, pp. 590-594, 2013.
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Nunes, D., T. R. Calmeiro, S. Nandy, J. V. Pinto, A. Pimentel, P. Barquinha, P. A. Carvalho, J. C. Walmsley, E. Fortunato, and R. Martins,
"{Charging effects and surface potential variations of Cu-based nanowires}",
Thin Solid Films: Elsevier B.V., pp. 1–9, 2015.
AbstractThe presentwork reports charging effects and surface potential variations in pure copper, cuprous oxide and cu- pric oxide nanowires observed by electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM). The copper nanowires were produced by wet synthesis, oxidation into cuprous oxide nanowires was achieved throughmicrowave irradiation and cupric oxide nanowireswere obtained via furnace annealing in at- mospheric conditions. Structural characterization of the nanowireswas carried out byX-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. During the EFM experiments the electrostatic field of the positive probe charged negatively the Cu-based nanowires, which in turn polarized the SiO2 dielectric substrate. Both the probe/nanowire capacitance as well as the sub- strate polarization increased with the applied bias. Cu2O and CuO nanowires behaved distinctively during the EFMmeasurements in accordancewith their band gap energies. Thework functions(WF) of the Cu-based nano- wires, obtained by KPFM measurements, yieldedWFCuO N WFCu N WFCu2O
Kardarian, K., D. Nunes, P. {Maria Sberna}, A. Ginsburg, D. A. Keller, J. {Vaz Pinto}, J. Deuermeier, A. Y. Anderson, A. Zaban, R. Martins, and E. Fortunato,
"{Effect of Mg doping on Cu2O thin films and their behavior on the TiO2/Cu2O heterojunction solar cells}",
Solar Energy Materials and Solar Cells, vol. 147, pp. 27–36, apr, 2016.
AbstractAbstract The present work shows the effect of magnesium doping on structural, optoelectrical and electrical properties of Cu2O thin films prepared by spray pyrolysis. The variation in the concentration of Mg shows significant impact on the final thin film properties, whereas the film doped with 0.5 at{%} of Mg exhibited major property improvements in comparison with the undoped thin film and among the other concentrations tested. This condition was further applied for the deposition of an absorber layer in a heterojunction solar cell array with a gradient in thicknesses of active layers to investigate the impact of changing thicknesses on the PV parameters of the solar cell. TiO2 was used as a window layer and the 0.5 at{%} Cu2O doped film as an absorber layer. The produced heterojunction solar cell array was further exposed to a rapid thermal annealing treatment. The I–V measurements show an open circuit voltage of up to 365 mV and a short circuit current density, which is dependent on absorber layer thickness, and reaches to a maximum value of 0.9 mA/cm2.
Morais, A. R. C., J. V. Pinto, D. Nunes, L. B. Roseiro, M. C. Oliveira, E. Fortunato, and R. Bogel-Łukasik,
"{Imidazole: Prospect Solvent for Lignocellulosic Biomass Fractionation and Delignification}",
ACS Sustainable Chemistry {&} Engineering: American Chemical Society, dec, 2015.
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