Multiphase structure of hydrogen diluted a-SiC:H deposited by HWCVD (original) (raw)
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Journal of Alloys and Compounds, 1999
Two series of hydrogenated amorphous silicon carbide (a-SiC:H) films have been prepared by using plasma-enhanced chemical-vapor deposition (PECVD) with the gas mixture of methane (CH ) and silane (SiH ). The influence of the r.f. power density on the structural 4 4 and optical properties of the films has been investigated with the CH gas ratio in the total gas flow rate ranging from 50 to 90%. The r.f. 4 power density is an important parameter which affects both the carbon content and the structures of the films. Under high r.f. power condition, the samples are Si-rich and the structure of them is described as a disordered amorphous silicon network in which hydrogen 3 atoms are incorporated in the form of Si-CH and Si-CH entities and carbon atoms are in a sp carbon-related configuration. The 2 3
2007
Hydrogenated amorphous silicon carbide (a-SiC:H) films were prepared using a home-built plasma-enhanced chemical vapor deposition (PECVD) system with different flow rate ratios of methane (CH(4)) and silane (SiH(4)) gases. Fourier-transform infrared (FTIR) spectra indicate multiple bonding configurations consisting of wagging, bending and stretching modes of silicon, hydrogen and carbon atoms with a steady depletion of Si-H wagging and stretching modes as the gas flow rate ratio increases. Micro-Raman spectra show evidence of amorphous silicon structure in all the films. Only the a-SiC:H film prepared at the highest CH(4) to SiH(4) gas flow rate ratio shows the existence of the Si-C vibrational mode. All the samples prepared show room-temperature luminescence with two peaks centered at 467 and 698 nm. The photoluminescence (PL) intensity increases as the CH(4) to SiH(4) gas flow rate ratio increases but a reduction in intensity is observed for a high CH(4) to SiH(4) gas flow rate ratio. a-SiC:H films with higher optical energy gaps were obtained by allowing the gases to flow at higher CH(4) to SiH(4) gas flow rate ratios.
Effect of substrate temperature on HWCVD deposited a-SiC:H film
Materials Letters, 2007
Hydrogenated amorphous silicon carbon (a-SiC:H) films were deposited using pure SiH 4 and C 2 H 2 without hydrogen dilution by hot wire chemical vapor deposition (HWCVD) technique. The photoluminescence, optical, and structural properties of these films were systematically studied as a function of substrate temperature (T s ). a-SiC:H films deposited at lower substrate temperature (T s ) show degradation in their structural, optical and network properties. The hydrogen content (C H ) in the films was found to be increased with decrease of T s studied. Photoluminescence spectra shift to higher energy and less FWHM at high T s . Raman spectroscopic analysis showed that structural disorder increases with decrease in the T s .
Journal of Materials Science: Materials in Electronics, 2014
Silicon carbide (SiC) thin films were deposited using hot wire chemical vapor deposition (HWCVD) technique from pure silane and methane gas mixture. The effect of filament distance to the substrate on the structural and optical properties of the films was investigated. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman scattering spectroscopy and UV-Vis-NIR spectroscopy were carried out to characterize SiC films. XRD patterns of the films indicated that the film deposited under highest filament-to-substrate distance were amorphous in structure, while the decrease in distance led to formation and subsequent enhancement of crystallinity. The Si-C bond density in the film structure obtained from FTIR data, showed significant increment with transition from amorphous to nano-crystalline structure. However, it remained almost unchanged with further improvement in crystalline volume fraction. From Raman data it was observed that the presence of amorphous silicon phase and sp 2 bonded carbon clusters increased with the decrease in distance. This reflected in deterioration of structural order and narrowing the optical band gap of SiC films. It was found that filament-to-substrate distance is a key parameter in HWCVD system which influences on the reactions kinetics as well as structural and optical properties of the deposited films.
Microstructure analysis of a-SiC: H thin films grown by high-growth-rate PECVD
Hydrogenated amorphous silicon carbide (a-SiC:H) thin films were synthesized by a non-conventional Plasma Enhanced Chemical Vapor Deposition (PECVD) system in which a 350 kHz High Frequency (HF) is coupled to the standard 13.56 MHz Radio Frequency (RF). Varying the methane to silane gas flux rate in a high power regime, a series of a-SiC:H layers were deposited on silicon substrates with a carbon ratio ranging from 0.25 to 0.46. A very high growth rate up to 150 Å /s coupled with a very large homogeneity of both thickness and composition (less than 1.5% on 6 in. Si wafers) were achieved. A careful analysis of chemical composition and microstructure of the films was performed combining Infrared and Micro-Raman spectroscopies.
Solar Energy Materials and Solar Cells, 1994
Hydrogenated amorphous and microcrystalline silicon carbon alloy films have been grown by photo-CVD using C2H 2 as a source gas of carbon. The hydrogenated amorphous silicon carbon (a-SiC : H) film with a band gap of ~ 2.0 eV prepared at a very low hydrogen (LD) concentration exhibits better photo-electronic properties compared to that at high hydrogen dilution (HD) having a similar optical gap. Notwithstanding a high deposition rate, the high photosensitivity (~ 106), the low density of the defect states (~ 6 X 1016 cm -3) and the Urbach energy parameter (72 meV) for the a-SiC:H film prepared at low hydrogen dilution and pressure are impressive. On the other hand, low pressure along with high hydrogen dilution have been found to be conducive to microcrystalline silicon carbon alloy (/~c-Si:H) formation. Interestingly, crystallites are of silicon while carbon remains in the amorphous and grain boundary regions.
Acta Physica Polonica A, 2016
The attention has been focused on the optical properties of structures of the form Au/MS/a-Si1−xCx:H/Si(100)/Al as a function of the deposition temperature of the a-Si1−xCx:H films. The amorphous SiC:H films were obtained for different temperatures ranging from 150 • C up to 500 • C. By photoluminescence, blue emission from all the structures was observed at room temperature and a high emission was obtained for sample whose amorphous film was deposited at 500 • C. The spectral response of Au/MS/a-Si1−xCx:H/Si(100)/Al structures with a-Si1−xCx:H film deposited at 250 • C, exhibits a maximum value at λ = 950 nm while for structure with a-Si1−xCx:H film obtained at 150 • C, a maximum value of λ was observed at 400 nm.