Effect of deposition temperature on the properties of magnetron sputtered hydrogenated amorphous silicon films

Abstract

Hydrogenated amorphous silicon films have been prepared by planar rf magnetron sputtering method. The effect of deposition temperature and the hydrogen dilution on the optoelectronic as well as structural properties of the films have been investigated. Parametric variations have yielded films with a wide spectrum of optoelectronic properties. Two useful results have come out of this study. First-the attractive optoelectronic properties obtained for films deposited near room temperature. This may be important from the viewpoint of potential utilisation in photovoltaic devices, where a high deposition temperature is liable to induce diffusion between the intrinsic and doped layer. The second interesting result is the realisation of undoped a-Si:H with wide optical band gap (~1.9-2.0 eV) showing high photoconductivity (~10^-5-10^-6 Ω^-1 cm^-1) and large ratio of photoconductivity to dark conductivity (~10⁴-10⁵). This suggests an alternative to the p-type a-SiC:H films as a window layer in a-Si solar cells, after p-type doping.