Study of optical parameters of sulphur doped Se-As thin films as optical materials

A conventional thermal evaporation technique has been used for thin film preparation of Se40As60_ySy (y = 0, 10, 20) chalcogenide materials. Optical characterization has been done in the wavelength range of 600-2700 nm in the thin films of above mentioned materials. Various optical parameters like refractive index, extinction coefficient, dielectric constant, dielectric loss, absorption coefficient and band gap have been calculated after the analysis of transmission spectra of the given samples. On the basis of optical parameters the optical characteristics have been discussed for Se40As60_ ySy (y = 0, 10, 20) materials. Optical band gap is estimated by using Tauc's extrapolation and is found to increase with S addition. This behavior of optical band gap is interpreted in terms of co-ordination number and chemical bond energy. The outcomes of optical characterization motivated towards to find the scope of present glassy system as optical materials.