b b b b b b b Martins, R.a b, Figueiredo Silva Águas Soares Marques Ferreira Fortunato J. a V. a. "
32 Linear array position sensitive detector based on NIP and hetero a-Si:H microdevices."
Journal of Non-Crystalline Solids. 299-302 (2002): 1283-1288.
AbstractIn this paper we present results concerning the performance exhibited by an integrated array of 32 one-dimensional amorphous silicon thin film position sensitive detectors based on nip and hetero amorphous silicon structures, with a total active area size below 1 cm2 linearity, its spatial resolution and response time, that make it one of the most interesting analog detector to be used in unmanned optical inspection control systems where a continuous detection process is required. This opens a wide range of applications for amorphous silicon devices in the area of image processing. © 2002 Elsevier Science B.V. All rights reserved.
Mei, S.a, Yang Ferreira Martins J. a J. M. "
Aqueous tape casting of low-k cordierite substrate: The influence of glass content."
Materials Science Forum. 455-456 (2004): 168-171.
AbstractThick films of cordierite-based glass ceramics were prepared by aqueous tape casting from suspensions containing 80-wt% solids. The weight proportions of cordierite/glass ranged from 70/30 to 30/70 in order to investigate the effect of glass content on the rheological behaviour and on the microstructures and properties of the green tapes. Suspensions with 50 to 60-wt% glass content exhibited the lowest viscosity values among all the slurries investigated, while the green tape containing 30-wt% glass presented homogenous microstructures at both top and bottom surfaces, contrarily to the observations for the other compositions. The green densities increased with glass content. The sintered tapes (1150°C, 2h) containing 50 to 60-wt% glass exhibited the lowest values for the dielectric constant (∼5.2) and dielectric loss (∼0.002) at 1MHz.
i Martins, R.a, Águas Ferreira Fortunato Raniero Roca Cabarrocas H. a I. a. "
Composition, structure and optical characteristics of polymorphous silicon films deposited by PECVD at 27.12 MHz."
Materials Science Forum. 455-456 (2004): 100-103.
AbstractThis paper presents data concerning the composition structure and optical characteristics of polymorphous silicon films produced by plasma enhanced chemical vapour deposition at 27.12 MHz and determined respectively by infrared spectrometry, micro Raman, exodiffusion and spectroscopic ellipsometry measurements. When compared to the pm-Si:H films produced at 13.56 MHz, the films produced at 27.12 MHz present hydrogen contents in the range of 21 at%, the sharp peak ascribed to the exodifusion measurements is shifted towards high temperatures and the imaginary part of the dielectric function 〈ε2〉 is larger and shifted to high energies. Apart from that the peaks of the infrared spectra ascribed to the stretching modes shift towards high wave numbers and the half width of the micro Raman peaks shrinks, meaning that the films produced at 27.12 MHz are more compact and dense.
b b b b b b b Martins, R.a b, Carvalho Fortunato Maçarico Santos Baia Viera Guimarães N. a E. a. "
Effects of U.V. light on the transport properties of a-Si : H films during their growth."
Journal of Non-Crystalline Solids. 97-98 (1987): 1399-1402.
AbstractThe influence of U.V. light on the transport properties of a-Si : H films during its growth in a r.f. double chamber system was investigated by conductivity, optical absorption, I.R. absorption, spectral photoconductivity and X-ray diffraction measurements. It was concluded that the presence of U.V. light during the deposition process controls the way how hydrogen is incorporated in the structure as well as the impurity atoms. The microcrystalline films investigated present sharp peaks in the I.R. spectra. Both boron and phosphorus doped films show conductivities higher than 10 S cm-1 and estimated crystalline sizes of the order of 80 Å. © 1987.
Martins, R., Ferreira Carvalho Guimarães I. N. L. "
Engineering of plasma deposition systems used for producing large area a-Si:H devices."
Journal of Non-Crystalline Solids. 137-138 (1991): 757-760.
AbstractOne of the main problems in producing large area amorphous silicon devices concerns films uniformity. In this paper we present data concerning the role of reactor geometry and design and on the film performances as well as the problems related to mechanical mismatches in scaling up the reactor size. © 1991 Elsevier Science Publishers B.V. All rights reserved.
Martins, R., Ferreira Fortunato I. E. "
Growth model of gas species produced by the hot-wire and hot-wire plasma-assisted techniques."
Key Engineering Materials. 230-232 (2002): 603-606.
AbstractThe model presented is based on the heat transfer and energy balance equations that rule the set of physical and chemical interactions that take place on the gas phase of a growth process, assuming that the deposition process occurs under laminar dynamic flow conditions (Knudsen number below 1). In these conditions, the chemistry and physics of the process involved in the growth mechanism of silicon thin films produced by the hot wire or the hot-wire plasma assisted technique can be proper derived by balance equations that supply information about how the plasma density, the gas dilution and the gas temperature influence the growth mechanism and the equilibrium of the concentration of species presented on the growth surface. The model developed establishes a relation between the abundance species formed and the parameters initiators of the process such as the filament temperature and the rf power density used.