Optical Constants of Cd0.8Zn0.2S Thin Films from Transmission Spectrum

Transmission spectrum of the Cd_0.8Zn_0.2S thin films prepared by vacuum evaporation, at normal incidence was obtained in the spectral region from 400 to 2000 nm. Based on the use of the maxima and minima of the interference fringes, a straightforward analysis proposed by Swanepoel´s method has been applied to derive the optical constants such as refractive index, n, absorption coefficients, a, optical band gap, E_g and the film thickness, d. The analysis of the optical absorption data revealed that the thin films were direct transition materials.