IMPROVEMENT OF PHOTOCONDUCTIVITY OF A-SIC-H FILMS BY INTRODUCING NITROGEN DURING MAGNETRON SPUTTERING PROCESS

Nitrogen has been introduced in the preparation of hydrogenated amorphous silicon carbon alloy films by magnetron sputtering of silicon in a methane-argon gas mixture. The partial pressure of nitrogen was changed, and its effects on the structural, optical, electrical, and optoelectronic properties of the deposited films were investigated. The Si-N bond becomes predominant with increasing partial pressure of nitrogen p(N) above 10%, at which the optical band gap is rapidly increased. The concentration of silicon and carbon in the films remained almost unchanged by changing p(N) up to 20%. It was found that the photoconductivity is also almost unchanged up to 20%, while the optical band gap is increased. This indicates that the photoconductivity is improved over a wider optical band gap, as compared with previous studies when the optical band gap was changed by changing deposition conditions but without introducing nitrogen.