Structural, optical and electronic properties of amorphous SiC: H alloys prepared by magnetron sputtering of silicon in methane-argon gas mixtures

Abstract

Abstract Amorphous Si1−x C x :H films have been prepared by the r.f. magnetron sputtering method using a silicon target in a gas mixture of argon and methane. The carbon content x was varied by varying the partial pressure of methane with respect to the total gas pressure. The dependence of the optical, structural and electrical properties on x has been investigated. With increasing x, the optical band gap increases owing to the hydrogenation of silicon in the region of small x and to the increase in the number of Si-C bonds in the large-x range, according to evidence from infrared spectra. While the dark conductivity decreases with increasing x, the photoconductivity shows a maximum at about x = 0·2. The photoconductivity increases in the range of x below 0·2 owing to the hydrogenation of silicon. Although it decreases in the range of x above 0·2, the values are larger than those of films prepared by glow-discharge decomposition of methane-silane gas mixtures reported in the literature. This is interpret...