F. IACOMI, M. PURICA, E. BUDIANU, D. MACOVEI
Transparent and Conductive CdS Thin Films – Preparation and Structural and Optical Investigation

Abstract.
The Mn, Sb and Se doped CdS thin films have been prepared using vacuum thermally evaporated mixed powders and were deposited onto silicon wafer and glass substrates. The deposited CdS films have been investigated regarding to structure, surface morphology, optical and electrical properties by XRD, AFM, XPS, optical spectroscopy and electrical measurements. The thin films have a textured hexagonal structure and after a heat treatment at 723 K become all transparent and have a low reflectivity. The XPS spectra indicates an enrichment of the film surface by sulphur (S:Cd = 1.24), with respect to the CdS stoichiometry. The substrate nature (glass and silicon) seems to less influence the composition of the CdS:Se films and for the both the position of the Se 3d peak suggests the formation of the Cd-Se bonds, similar to those in the CdSe compound. The heat treatment increases the thin films transmission for all the studied samples and the transmittance was in all cases higher than 50%. Temperature dependence of electrical conductivity in the high and low temperature region suggests the grain boundary limited and variable range hopping conduction as dominant conduction mechanisms. The CdS thin films doped with Sb and Se perform a relatively high electrical conductivity.