Determination of optical constants of Zn_xIn_1-xSe thin films deposited by evaporation

Polycrystalline Zn_xIn_1-xSe 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 In₂Se₃ compounds using a crucible constituted by two coaxial chambers. The optical constants (refractive index n, absorption coefficient α 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, α and d obtained experimentally.