Chemical Vapor Deposition of a-SiGe:H Films Utilizing a Microwave-Excited Plasma

Abstract

Hydrogenated amorphous silicon-germanium films were prepared by a chemical vapor deposition method utilizing a microwave-excited plasma produced at low gas pressures (∼10 -3 Torr). Deposition methods in which SiH 4 and GeH 4 were decomposed by a plasma stream of Ar or hydrogen or by direct excitation were examined at 200°C and at the pressures optimized for the preparation of hydrogenerated amorphous silicon films. Highly photoconductive narrow gap films (an optical gap of 1.5 eV) with photoconductivity higher than 10 -5 S/cm and photosensitivity of about 10 4 were obtained by these methods, keeping a high deposition rate.