Some properties of indium-and antimony-doped vacuum-evaporated CdS thin films

Abstract

The effects of doping of vacuum-evaporated CdS thin films with indium and antimony were studied. The properties specifically studied are (1) the dark conductivity and photoconductivity as functions of temperature and dopant concentration, (2) the Hall mobility and carrier concentration at room temperature, (3) the thermally stimulated current and (4) the spectral response and optical density. For indium-doped CdS films, in agreement with previous studies the dopant was found to act as a donor as it is a group III element and replaces cadmium in CdS. Thus the dark conductivity and carrier concentration are increased. Doping with antimony results in a sharp decrease in the dark conductivity, Hall mobility and carrier concentration. This behaviour is also expected as antimony is a group V element which replaces sulphur in CdS so that it acts as an acceptor. The nature of log σ_D versus 10³/T curves for antimony-doped CdS thin films was found to be similar to that obtained for some amorphous semiconductor thin films. Study by X-ray diffraction showed the antimony-doped CdS films be amorphous.