Papers by Author: Leandro Raniero

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Authors: Leandro Raniero, Hugo Águas, Luís Pereira, Elvira Fortunato, Isabel Ferreira, Rodrigo Martins
Authors: Rodrigo Martins, Hugo Águas, Isabel Ferreira, Elvira Fortunato, Leandro Raniero, Pere Roca i Cabarrocas
Authors: Leandro Raniero, Rodrigo Martins, Hugo Águas, S. Zang, Isabel Ferreira, Luís Pereira, Elvira Fortunato, L. Boufendi
Authors: N. Nedev, G. Beshkov, Elvira Fortunato, S.S. Georgiev, T. Ivanov, Leandro Raniero, Shibin Zhang, Rodrigo Martins
Authors: Rodrigo Martins, Daniel Costa, Hugo Águas, Fernanda Soares, António Marques, Isabel Ferreira, P.M.R. Borges, Sergio Pereira, Leandro Raniero, Elvira Fortunato
Abstract: This work aims to report results of the spatial and frequency optical detection limits of integrated arrays of 32 one-dimensional amorphous silicon thin film position sensitive detectors with nip or MIS structure, under continuous and pulsed laser operation conditions. The arrays occupy a total active area of 45 mm2 and have a plane image resolution better than 15 m with a cut-off frequency of about 6.8 kHz. The non-linearity of the array components varies with the frequency, being about 1.6% for 200 Hz and about 4% for the cut-off frequency (6.8 kHz).
Authors: Hugo Águas, Luís Pereira, Leandro Raniero, Elvira Fortunato, Rodrigo Martins
Authors: Elvira Fortunato, Alexandra Gonçalves, António Marques, Ana Pimentel, Pedro Barquinha, Hugo Águas, Luís Pereira, Leandro Raniero, Gonçalo Gonçalves, Isabel Ferreira, Rodrigo Martins
Abstract: In this paper we report some of the recent advances in transparent thin film oxide semiconductors, specifically zinc oxide (ZnO), produced by rf magnetron sputtering at room temperature with multifunctional properties. By controlling the deposition parameters it is possible to produce undoped material with electronic semiconductor properties or by doping it to get either n-type or p-type semiconductor behavior. In this work we refer our experience in producing n-type doping ZnO as transparent electrode to be used in optoelectronic applications such as solar cells and position sensitive detectors while the undoped ZnO can be used as UV photodetector or ozone gas sensor or even as active layer of fully transparent thin film transistors.
Authors: Leandro Raniero, Alexandra Gonçalves, Ana Pimentel, Shibin Zhang, Isabel Ferreira, Paula M. Vilarinho, Elvira Fortunato, Rodrigo Martins
Abstract: In this work we studied the influence of the power density of hydrogen plasma on electrical and optical properties (Hall mobility, free carrier concentration, sheet resistance, optical transmittance and a.c. impedance) of indium zinc oxide films, aiming to determine their chemical stability. This is an important factor for the optimization of amorphous/nanocrystalline p-i-n hydrogenated silicon (a/nc-Si:H) solar cells, since they should remain chemically highly stable during the p layer deposition. To perform this work the transparent conductive oxide was exposed to hydrogen plasma at substrate temperature of 473 K, 87 Pa of pressure and 20 sccm of hydrogen flow. The results achieved show that IZO films were reduced for all plasma conditions used, which leads mainly to a decrease on films transmittance. For the lowest power density used in the first minute of plasma exposition the transmittance of the IZO films decreases about 29%.
Authors: Luís Pereira, Hugo Águas, Leandro Raniero, Rui Miguel S. Martins, Elvira Fortunato, Rodrigo Martins
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