Fortunato, E., Martins R. "
Role of the collecting resistive layer on the static characteristics of 2D a-Si:H thin film position sensitive detector."
Materials Research Society Symposium - Proceedings. Vol. 507. 1999. 303-308.
AbstractThe aim of this work is to present an analytical model able to interpret the role of the thin collecting resistive layer on the static performances exhibited by 2D amorphous silicon hydrogenated pin thin film position sensitive detectors. In addition, experimental results concerning the device linearity and spatial resolution are presented and checked against the predicted values of the analytical model proposed.
Fortunato, E., Vieira Ferreira Carvalho Lavareda Martins M. L. C. "
Large area position sensitive detector based on amorphous silicon technology."
Materials Research Society Symposium Proceedings. Vol. 297. 1993. 981-986.
AbstractWe have developed a rectangular dual-axis large area Position Sensitive Detector (PSD), with 5 cm×5 cm detection area, based on PIN hydrogenated amorphous silicon (a-Si:H) technology, produced by Plasma Enhanced Chemical Vapor Deposition (PECVD). The metal contacts are located in the four edges of the detected area, two of them located on the back side of the ITO/PIN/Al structure and the others two located in the front side. The key factors of the detectors resolution and linearity are the thickness uniformity of the different layers, the geometry and the contacts location. Besides that, edge effects on the sensor's corner disturb the linearity of the detector. In this paper we present results concerning the linearity of the detector as well as its optoelectronic characteristics and the role of the i-layer thickness on the final sensor performances.
Fortunato, E., Nunes Marques Costa Águas Ferreira Costa Martins P. A. D. "
Highly conductive/transparent ZnO:Al thin films deposited at room temperature by rf magnetron sputtering."
Key Engineering Materials. 230-232 (2002): 571-574.
AbstractTransparent conducting ZnO:Al thin films have been deposited on polyester (Mylar type D, 100 μm thickness) substrates at room temperature by r.f. magnetron sputtering. The structural, optical and electrical properties of the deposited films have been studied. The samples are polycrystalline with a hexagonal wurtzite structure and a strong crystallographic c-axis orientation (002) perpendicular to the substrate surface. As deposited ZnO:Al thin films have an 85% transmittance in the visible and infra-red region and a resistivity as low as 3.6×10-2 Ωcm. The obtained results are comparable to those ones obtained on glass substrates, opening a new field for low cost, light weight, small volume, flexible and unbreakable large area optoelectronic devices.
Fortunato, E., Nunes Marques Costa Águas Ferreira Costa Martins P. A. D. "
Thin film metal oxide semiconductors deposited on polymeric substrates."
Materials Research Society Symposium - Proceedings. Vol. 666. 2001. F1131-F1136.
AbstractHighly textured transparent conducting ZnO:Al thin films have been prepared by r.f. magnetron sputtering. The films were deposited on polyester (Mylar type D, 100 μm thickness) and glass substrates at room temperature. Surface stylus profiling, X-ray diffraction, scanning electron microscopy, transmission electron microscope and Hall effect measurements as a function of temperature have been used to characterize the produced films. The samples are polycrystalline with a hexagonal wurtzke structure and a strong crystallographic c-axis orientation (002) perpendicular to the substrate surface (columnar structure). The ZnO:Al thin films with a resistivity as low 3.6×10-2 Ωcm have been obtained, as deposited.
Fortunato, E., Gonçalves Marques Assunção Ferreira Águas Pereira Martins A. A. V. "
Gallium zinc oxide coated polymeric substrates for optoelectronic applications."
Materials Research Society Symposium - Proceedings. Vol. 769. 2003. 291-296.
AbstractHighly transparent and conductive ZnO:Ga thin films were produced by rf magnetron sputtering at room temperature on polyethylene naphthalate substrates. The films present a good electrical and optical stability, surface uniformity and a very good adhesion to the polymeric substrates. The lowest resistivity obtained was 5×10-4 Ωcm with a sheet resistance of 15 Ω/sqr and an average optical transmittance in the visible part of the spectra of 80%. It was also shown that by passivating the polymeric surface with a thin SiO2 layer, the electrical and structural properties of the films are improved nearly by a factor of 2.
Fortunato, E.M.C., Brida Ferreira Águas Nunes Cabrita Giuliani Nunes Maneira Martins D. I. M. M. "
Large area flexible amorphous silicon position sensitive detectors."
Materials Research Society Symposium - Proceedings. Vol. 609. 2000. A1271-A1276.
AbstractLarge area thin film position sensitive detectors based on amorphous silicon technology have been prepared on polyimide substrates using the conventional plasma enhanced chemical vapour deposition technique. The sensors have been characterised by spectral response, illuminated I-V characteristics and position detectability measurements. The obtained one dimensional position sensors with 5 mm wide and 60 mm long present a maximum spectral response at 600 nm, an open circuit voltage of 0.6 V° and a position detectability with a correlation of 0.9989 associated to a standard deviation of 1 × 10-2, comparable to those ones produced on glass substrates. The surface of the sensors at each stage of fabrication was investigated by Atomic Force Microscopy.
Fortunato, E., Soares Lavareda Martins F. G. R. "
New linear array thin film position sensitive detector (LTFPSD) for 3D measurements."
Materials Research Society Symposium - Proceedings. Vol. 377. 1995. 797-802.
AbstractA Linear array Thin Film Position Sensitive Detector (LTFPSD) based on hydrogenated amorphous silicon (a-Si:H) is proposed for the first time, taking advantage of the optical properties presented by a-Si:H devices we have developed a LTFPSD with 128 integrated elements able to be used in 3D inspections/measurements. Each element consists on an one-dimensional TFPSD, based on a p.i.n. diode produced in a conventional PECVD system, where the doped layers are coated with thin resistive layers to establish the required device equipotentials. By proper incorporation of the LTFPSD into an optical inspection camera it will be possible to acquire information about an object/surface, through the optical cross-section method. The main advantages of this system, when compared with the conventional CCDs, are the low complexity of hardware and software used and that the information can be continuously processed (analogue detection).
Fortunato, E., Pimentel Gonçalves Marques Martins A. A. A. "
High mobility nanocrystalline indium zinc oxide deposited at room temperature."
Materials Research Society Symposium Proceedings. Vol. 811. 2004. 437-442.
AbstractIn this paper we present results of indium doped zinc oxide deposited at room temperature by rf magnetron sputtering, with electron mobility as high as 60 cm2/Vs. The films present a resistivity as low as 5×10 -4 Ωcm with an optical transmittance of 85%. The structure of these films look-like polymorphous (mixed of different amorphous and nanocrystalline phases from different origins) as detected from XRD patterns (no clear peak exists) with a high smooth surface, as detected from SEM micrographs, highly important to ensure long life time when used in display devices.
Fortunato, E.a, Assunção Gonçalves Marques Águas Pereira Ferreira Vilarinho Martins V. a A. a. "
High quality conductive gallium-doped zinc oxide films deposited at room temperature."
Thin Solid Films. 451-452 (2004): 443-447.
AbstractTransparent and highly conducting gallium-doped zinc oxide films were successfully deposited by rf sputtering at room temperature. The lowest resistivity achieved was 2.6×10-4 Ω cm for a thickness of 1100 nm (sheet resistance ≈1.6 Ω/sq), with a Hall mobility of 18 cm2/Vs and a carrier concentration of 1.3×1021 cm-3. The films are polycrystalline with a hexagonal structure and a strongly preferred orientation along the c-axis. A linear dependence between the mobility and the crystallite size was obtained. The films present a transmittance in the visible spectra between 80 and 90% and a refractive index of approximately 2, which is very close to the value reported for bulk material. © 2003 Elsevier B.V. All rights reserved.