Structure and properties of hydrogenated amorphous silicon carbide thin films deposited by PECVD

a-Si1−xCx:H films are deposited by RF plasma enhanced chemical vapor deposition (PECVD) at different RF powers with hydrogen-diluted silane and methane mixture as reactive gases. The structure and properties of the thin films are measured by infrared spectroscope (IR), Raman scattering spectroscope and ultra violet-visible transmission spectroscope (UV-vis), respectively. Results show that the optical band gap of the a-Si1−xCx:H thin films increases with increasing Si-C bond fraction. It can be easily controlled through controlling Si-C bond formed by modulating deposition power. At low deposition power, the bond configuration of the a-Si1−xCx:H thin film is more disordered owing to the distinct different bond lengths and bond strengths between Si and C atoms. At a too high deposition power, it becomes still high disordered due to dangling bonds appearing in the a-Si1−xCx:H thin film. The low disordered bond configuration appears in the thin film deposited with moderate deposition power density of about 2.5 W/cm2.