Electrical properties before and after light-soaking of hydrogenated amorphous silicon carbide films prepared by the hydrogen radical CVD method

Abstract

Hydrogenated amorphous silicon carbide (a-Si1-xCx:H) films were prepared by use of the preparation system possessing a hydrogen plasma chamber and a silane/methane plasma chamber (the hydrogen radical chemical vapour deposit (CVD) method) and their electrical properties before and after light-soaking were investigated. The photo- and dark conductivities both before and after light-soaking increased with increasing rf power on the hydrogen plasma side; however, the photosensitivity remained unchanged. The activation energy of the dark conductivity before light-soaking decreased with increasing rf power on the hydrogen plasma side, while that after light-soaking increased. The defect density decreased with increasing rf power on the hydrogen plasma side. The hydrogen radical CVD method was found to be useful for preparing a-Si1-xCx:H films with high photoconductivity and low defect density. The electrical properties obtained in this study were explained by the two-energy-level model. Although the hydrogen radical CVD method mainly reduced the defect density of the lower energy level, it also reduced that of the upper energy level.