Determination of optical constants of Zn$\pmb{_{x}}$In$\pmb{_{1 - x}}$Se thin films deposited by evaporation

Abstract

Polycrystalline Zn$_{x}$In$_{1 - x}$Se thin films with Se contents varying between x=0 (InSe) and x=1 (ZnSe), deposited on glass substrates, were optically characterized. These samples were grown by coevaporation of the ZnSe and In$_{2}$Se$_{3}$ compounds using a crucible constituted by two coaxial chambers. The optical constants (refractive index n, absorption coefficient $\alpha$ and optical gap Eg) and the film thickness d, were determined using the transmission spectrum and simple calculations based on a theoretical model including interference effect induced by multiple internal reflections in the substrate/film system. The reliability of the results was tested by comparing the experimental transmittance spectra with the theoretically ones, using values of n, $\alpha$ and d obtained experimentally.