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.