Fabrication and characteristics of hydrogenated amorphous carbon films by low frequency PECVD method with methane plasma

Hydrogenated amorphous carbon (a-C:H) films were prepared by low frequency (60 Hz) plasma enhanced chemical vapor deposition (LF-PECVD). Reactive plasma using gaseous mixture of CH4 and Ar was generated by a low frequency (60 Hz) power with a simple booster. The characteristics of a-C:H films were analyzed by Raman spectroscopy, Fourier transform infrared spectroscopy, UV-VIS-IR spectroscopy, scanning electron microscope and AFM. The deposition rate of films increased initially and then decreased after passing a maximum with increasing CH4 dilution. The optical gap, sp3/sp2 ratio, hydrogen content increased with increasing CH4 dilution. As a result, we found that CH4 partial pressure affects the deposition of a-C:H films sensitively