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The effects of dissipated power and gas dwell time in SiH4+CH4 plasmas on the properties of a‐SiC:H films deposited by plasma‐enhanced chemical‐vapor deposition have been investigated for different methane fractions in plasmas operating in the low‐power regime. Optical, structural, and electrical characterizations have been performed in order to investigate the influence of dissipated power and molecule dwell time on the physical properties of a‐SiC:H films. It was found that both the investigated deposition parameters can have a remarkable influence on carbon incorporation and on optical properties such as the energy gap. In particular an increase in the dissipated power or in the molecule dwell time leads to an increase in carbon incorporation and in energy gap. The electrical properties and defect density are still those of device quality films grown in standard deposition conditions and are not influenced by variations in dissipated power or gas dwell time. From these results some conclusions regardin...

Amorphous silicon‐nitrogen, a‐SiNx:Hy, thin films with optical gap in the range 2.0–5.2 eV have been deposited by 13.56 MHz ultra‐high‐vacuum plasma enhanced chemical vapor deposition system in SiH4+NH3 gas mixtures. Compositional, optical, dark and photoelectrical and defect characterizations have been performed in order to show that a‐SiNx:Hy films can be applied in optoelectronic technology as wide band‐gap semiconductor. A comparison between electronic properties of a‐SiNx:Hy samples and device quality a‐Si1−xCx:H films, already applied in electronic devices, has been carried out. Amorphous silicon‐nitrogen films show high deposition rates, good controllability of optical gap, and electronic properties similar to high‐quality silicon‐carbon films. No doping effect of nitrogen atoms in tetrahedral configuration has been evidenced and spin density below 7×1017 cm−3 have been measured in a‐SiNx:Hy films with optical gap as high as 5.2 eV.

Amorphous and microcrystalline silicon carbide, undoped and doped, has attracted a great attention for its optical and electrical properties. The introduction of dopant atoms in the network of amorphous films permits the control of electrical properties but it gives rise to a decreasing of the optical gap. Microcrystalline SiC:H films seem to provide films having a wide range of electrical conductivities without drastic change in the optical gap. This paper presents the results of a detailed study on the effects of boron and phosphorus doping on structural, optical, and electrical properties of a‐SiC:H and μc‐SiC:H films. An optical gap as high as 2.1 eV, together with a conductivity of 10−3 Ω−1 cm−1, are shown by doped μc‐SiC:H.

The paper deals with structural, optical, and electrical properties of a‐SiC:H and a‐SiC:H,F films prepared by rf sputtering of a silicon target in Ar+H2+CH4 and Ar+H2+CF4 gas mixtures, respectively. The comparison of the physical properties of the two different sets of the samples has been considered and the influence of hydrogen and/or fluorine incorporation is examined and discussed.

The temperature dependence of the structural properties of a‐SiGe:H and a‐CSiGe:H films has been studied. The samples were characterized by differential scanning calorimetry, conductivity measurements, electron‐spin resonance, infrared, optical, and photoacoustic spectroscopy. The disagreement of previous results of differential scanning calorimetry on hydrogenated amorphous semiconductors samples (a‐Si:H and a‐Ge:H) is examined and discussed. The equilibration temperature determined by the temperature dependence of dc conductivity agrees well with that of the first exothermic process detected with differential calorimetry. The second exothermic effect occurs when hydrogen evolution starts, as confirmed by electron‐spin resonance and infrared spectroscopies.

An analysis of the optical parameters of amorphous solar cells to maximize the absorption of photons in the active region of the cell and then the short circuit current is presented. The model applied to several kinds of amorphous structures indicates that total optical losses of only 9% and short circuit currents up to 24.5 mA/cm2 can be achieved.

The a‐CSiSn alloy produced by rf magnetron sputtering in SiH4, CH4, and Ar atmosphere was studied as a function of the substrate temperature. The composition of the films was determined by elastic recoil detection analysis and by Rutherford backscattering measurements, and the density was then deduced. Results of a study of optical and electrical properties and of the bonding and structure of the films indicate that with the increase of the substrate temperature, the density and the imaginary part of the dielectric constant increases, the optical gap decreases, and the dark conductivity presents a different conduction mechanism depending on the substrate temperature. A correlation between the results obtained from nuclear measurements and IR spectroscopy is presented.

The optical properties of undoped α‐Si:H films prepared using magnetron sputtering at different deposition conditions were studied by measuring their transmittance and reflectance between λ=0.25 and λ=1.5 μm and their thickness. The extracted optical constants are interpreted to give values of the band gap. Values of dark conductivity and activation energy are also obtained. The study has been extended to structures SnO2/α‐Si:H/substrate. From measurements of transmittance and reflectance of the system optical constants of the components can be extracted.