Thin film hydrogenated silicon-sulphur alloys as promising materials for solar cell applications

Abstract

Compositionally graded hydrogenated amorphous silicon-sulphur alloys were grown by r.f. glow discharge decomposition of silane and hydrogen sulphide at a substrate temperature of 250°C. The composition of the alloys was controlled by changing the gas volume ratio R v = [ H 2 S] [ SiH 4] . IR spectra reveal clear evidence for the incorporation of sulphur in the form of Si—S bonds in the material. Although there is a decrease in the photoconductivity σ ph with increasing E opt, the photosensitivity σ ph/σ d remains high, exceeding 10 3 throughout the whole alloy range. The compositionally graded layers display high photosensitivities, indicating that they may be of use in amorphous-silicon-based solar cells.