Determination of optical parameters of α-(As2Se3)90Ge10 thin film

A thin film of the ternary chalcogenide glassy alloy (As2Se3) Ge-90(10) has been deposited on a glass substrate by the thermal evaporation technique under vacuum. The optical parameters, refractive index (n) and extinction coefficient (k), have been calculated in the wavelength range 400-1500 nm by analysing the transmission spectrum. The dispersion of the refractive index is described in terms of a Wemple-DiDomenico single oscillator model. The value of the static refractive index has been found to be 2.518. The optical absorption edge is described using a non-direct transition model proposed by Tauc and the optical band gap (E opt g) calculated by Tauc's extrapolation is 1.58 +/- 0.01 eV. The dielectric properties and optical conductivity has also been calculated.