Determination of optical parameters ofa-(As₂Se₃)₉₀Ge₁₀thin film

A thin film of the ternary chalcogenide glassy alloy (As 2 Se 3 ) 90 Ge 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 calculated by Tauc's extrapolation is 1.58 ± 0.01 eV. The dielectric properties and optical conductivity has also been calculated.