Influence of S/Sb ratio on the principal optical parameters of the amorphous films

Optical properties of amorphous S100−x Sbx (x = 10, 20, 30 and 40 at.%) films prepared by thermal evaporation technique have been measured in the ultraviolet-visible and near infrared spectral region. The maximum value of the refractive index, n, is shifted towards the long wavelength by increasing the Sb content in the examined system. The absorption coefficient, α, has been determined from the transparency and reflectivity spectrum in the range 320-2500 nm. The values of optical energy gap and Urbach energy of the system have been determined. The optical-absorption data indicate that the absorption mechanism in an indirect transition. The oscillator energy, Eo, and dispersion energy, Ed, have been determined by the Wemple-Didomenico method.