A photoconductivity and Raman scattering analysis of boron-doped a-SiC:H films deposited using the electron cyclotron resonance plasma CVD method

Hydrogenated amorphous silicon carbide films (a-SiC:H) were deposited using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) technique from a mixture of methane, silane and hydrogen, with diborane as the doping gas. The effect of the microwave power on the deposition rate were studied, and variations in the photo and dark conductivities were investigated in conjunction with film analysis using the Raman scattering technique. The conductivity increases rapidly to a maximum, followed by rapid reduction at high microwave powers. The ratio of the photo to dark conductivity (σ _ph/σ_d) peaks at microwave powers of ~600 W. Under conditions of high hydrogen dilution and increasing microwave power, Raman scattering analysis showed evidence of the formation and increase of microcrystalline silicon and diamond-like components in the films, the former of which could account for the rapid increase and the latter the subsequent decrease in the conductivity