Optical and electrical properties of chlorinated and hydrogenated amorphous silicon prepared by glow discharge

Abstract

Chlorinated and hydrogenated amorphous silicon films were prepared by glow discharge of a SiCl 4/H 2 mixture. Infrared spectra of these films show that, in addition to the hydrogen induced bands, two new modes appear at 545 cm −1 (SiCl stretching) and 500 cm −1 (Si TO modes induced by chlorine). Observation of the 545 cm −1 band proves that chlorine is able to act as a dangling bond terminator in an amorphous silicon matrix. A good agreement is found between the total amount of chlorine determined by electron microprobe analysis and the value estimated from the integrated strength of the SiCl stretching mode. The relatively high value of the optical band gap (1.80 eV) of our material containing only 5 at.% bonded hydrogen shows that chlorine plays a major role in the optical gap value. Electrical conductivity, photoconductivity and luminescence properties are qualitatively similar to that of a: SiH films.