Effect of He on the optical and electrical properties of RF magnetron sputtered amorphous SiC:H films

Hydrogenated silicon–carbon alloy (SiC:H) films were deposited by reactive RF magnetron sputtering of Si in methane–argon gas mixtures. As a second sputtering gas, helium was used to control the film properties. The effect of the partial pressure ratio (R) of He to the total sputtering gas on the structural, optical, and electrical properties of the films was investigated. At R values above 70%, the bonding configuration observed in the IR spectra changed, the optical band gap decreased, and the DC conductivity clearly increased. These observations imply an increase in structural disorder after introducing a high R of He during the sputtering process. In order to overcome the negative effects on the properties of films deposited under high R values, the possibility of micro-crystallization in an amorphous structure was examined by introducing H2 instead of He.