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, Elvira, Lavareda Guilherme Martins Rodrigo Soares Fernando Fernandes Luis. "
From intelligent materials to smart sensors."
Proceedings of SPIE - The International Society for Optical Engineering. Vol. 2779. 1996. 269-274.
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 a 1D LTFPSD, 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, Elvira, Lavareda Guilherme Martins Rodrigo Soares Fernando Fernandes Luis. "
High-detection resolution presented by large-area thin-film position-sensitive detectors."
Proceedings of SPIE - The International Society for Optical Engineering. Vol. 2397. 1995. 259-270.
AbstractThe aim of this work is to present the main optoelectronic characteristics of large area 1D position sensitive detectors based on amorphous silicon p-i-n diodes. From that, the device resolution, response time and detectivity are derived and discussed concerning the field of applications of the 1D thin film position sensitive detectors.
Fortunato, E., Nunes Marques Costa Águas Ferreira Costa Martins P. A. D. "
Characterization of zinc oxide thin films deposited by rf magnetron sputtering on Mylar substrates."
Materials Research Society Symposium - Proceedings. Vol. 666. 2001. F3211-F3216.
AbstractAluminium doped zinc oxide thin films (ZnO:Al) have been deposited on polyester (Mylar type D, 100 μm thickness) substrates at room temperature by r.f. magnetron sputtering. The structural, morphological, 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. The ZnO:Al thin films with 85% transmittance in the visible and infra-red region and a resistivity as low as 3.6×10-2 Ωcm have been obtained, as deposited. The obtained results are comparable to those ones obtained on glass substrates, opening a new field of low cost, light weight, small volume, flexible and unbreakable large area optoelectronic devices.
Fortunato, E.a, Nunes Marques Costa Águas Ferreira Costa Martins P. a A. a. "
Thin film metal oxide semiconductors deposited on polymeric substrates."
Materials Research Society Symposium Proceedings. Vol. 685. 2001. 146-151.
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, using the van der Pauw technique have characterized the films. The samples are polycrystalline with a hexagonal wurtzite 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 as 3.6×10-2 Ωcm have been obtained, as deposited. © 2001 Materials Research Society.
Fortunato, E., Malik Seco Macarico Martins A. A. A. "
High sensitivity photochemical sensors based on amorphous silicon."
Materials Research Society Symposium - Proceedings. Vol. 467. 1997. 949-954.
AbstractHydrogenated amorphous silicon photochemical sensors based on Pd-MIS structures were produced by Plasma Enhanced Chemical Vapor Deposition with two different oxidized surfaces (thermal and chemical oxidation). The behaviour of dark and illuminated current-voltage characteristics in air and in the presence of a hydrogen atmosphere is explained by the changes induced by the gases in the work function of the metal, modifying the electrical properties of the interface. The photochemical sensors produced present more than 2 orders of magnitude variation on the reverse dark current when in presence of 400 ppm hydrogen to which it corresponds a decrease of 45% on the open circuit voltage.
Fortunato, E., Barquinha Pimentel Gonçalves Pereira Marques Martins P. A. A. "
Next generation of thin film transistors based on zinc oxide."
Materials Research Society Symposium Proceedings. Vol. 811. 2004. 347-352.
AbstractWe report high performance ZnO thin film transistor (ZnO-TFT) fabricated by rf magnetron sputtering at room temperature with a bottom gate configuration. The ZnO-TFT operates in the enhancement mode with a threshold voltage of 19 V, a field effect mobility of 28 cm2/Vs, a gate voltage swing of 1.39 V/decade and an on/off ratio of 3×105. The ZnO-TFT present an average optical transmission (including the glass substrate) of 80% in the visible part of the spectrum. The combination of transparency, high field-effect mobility and room temperature processing makes the ZnO-TFT a very promising low cost optoelectronic device for the next generation of invisible and flexible electronics.
Fortunato, E., Barquinha Martins P. R. "
New developments on oxide electronics."
Proceedings of the International Display Workshops. Vol. 3. 2011. 1681-1684.
AbstractIn this article we review the recent progress in n- and p-type oxide based thin film transistors (TFT), with special emphasis to solution-processed and p-type, and we will summarize the major milestones already achieved with this emerging and very promising technology.
Fortunato, E., Fernandes Soares Lavareda Martins M. F. G. "
From intelligent materials to smart sensors: a-Si:H position sensitive detectors."
Materials Research Society Symposium - Proceedings. Vol. 420. 1996. 165-170.
AbstractThis work presents the main static and dynamic performances showed by one dimensional thin film position sensitive detectors (1D TFPSD), based on a-Si:H technology, with a size of 80 mm × 5 mm. The results obtained show that the TFPSD is able to respond to light powers as low as 2μ W/cm2, presenting a detection accuracy, linearity and response frequency better than 10 μm, 2% and 2 KHz, respectively. These results are quite promising regarding the application of these sensors to a wide variety of optical inspection systems where continuous quality control is required.
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).