The optical and electrical characteristics of a-Si:H films prepared by ECR CVD

Abstract

The optical and electrical properties of hydrogenated amorphous silicon films, deposited by ECR plasma CVD, were investigated as a function of H/sub 2//SiH/sub 4/ ratio and as a function of substrate temperature. Photoconductivity increased with increasing SiH/sub 4/ gas content or with increasing substrate temperature, due to the decrease of optical band gap, FWHM and the ratio of the concentration of dihydride to that of monohydride. Dark conductivity decreased with increasing substrate temperature due to the increase of surface roughness, and was quite independent of H/sub 2//SiH/sub 4/ ratio. The influence factors of photoconductivity were hydride bonding configuration, optical band gap and FWHM. The dominant factor of dark conductivity was the surface roughness.