Influence of the film thickness on structural and optical properties of CdTe thin films electrodeposited on stainless steel substrates

Abstract

CdTe thin films of different thicknesses were deposited by electrodeposition on stainless steel substrates (SS). The dependence of structural and optical properties on film thickness was evaluated for thicknesses in the range 0.17–1.5 μm. When the film is very thin the crystallites lack preferred orientation, however, thicker films showed preference for (111) plane. The results show that structural parameters such as crystallite size, lattice constant, dislocation density and strain show a noticeable dependence on film thickness, however, the variation is significant only when the film thickness is below 0.8 μm. The films were successfully transferred on to glass substrates for optical studies. Optical parameter such as absorption coefficient (α), band gap (Eg), refractive index (n), extinction coefficient (ke), real (ɛr) and imaginary (ɛi) parts of the dielectric constant were studied. The results indicate that all the optical parameters strongly depend on film thickness.