Physical properties and structure of a-Si1−xCx:H alloy films

Two sets ofa-SiC:H films were deposited by glow discharge in an Ar-SiH4-CH4 atmosphere to investigate the effect of a variable CH4/SiH4 ratio on the physical properties. The composition of the films was determined by resonant nuclear reaction and by Rutherford backscattering measurements, the optical gap and the index of refraction by transmissivity measurements in the visible-UV-NIR range, the bonding configuration by IR transmissivity measurements and the resistivity and the photo-conductivity by electrical measurements in the dark and under a 500 W/m2 illumination. Results indicate that with increasing carbon content the refractive index decreases systematically over all wavelengths, the energy gap increases, the dark resistivity increases, the bonding configuration becomes dominated by carbon-containing chains and the structure more disordered.