Application of Spectroscopic Ellipsometry to Study the Effect of Annealing on Cadmium Sulphide Thin Films

Abstract

Multiple angle spectroscopic ellipsometery (SE) has been used to study the variation in the layer structure due to annealing of CdS thin films prepared by spray pyrolysis technique. The samples were studied using visible light having wavelength in the range 535 nm - 650 nm. The results obtained from the ellipsometric measurements were analysed assuming different multilayer models for the film structure. In the present work films of ~ 200 nm thickness were analysed and found that annealing at 300/sup0/C results in a two layer structure in the film with a thin defective layer on the top (of thickness 35 nm) and a thick bottom layer of better crystalline quality. Annealing at lower temperature resulted in a thick top defective layer. Studies using lower wavelengths revealed that the thick top layer itself is divided into several sublayers