Effect of tellurium addition on the optical and physical properties of germanium selenide glassy semiconductors

Thin films of the glasses Ge10 Se90−x Tex (0 ≤ x ≥ 40) have been prepared by melt quenching technique; thin films were evaporated at a pressure of ≈10−4 Pa. The optical absorption behavior of these thin films was studied from the reflection and transmission spectrum in the spectral range 200–1200 nm. The optical constants i.e optical band gap (Eopt), absorption coefficient, refractive index (n) are calculated. The optical band gap has been estimated using Tauc extrapolation and found to decrease with Te content. The Dispersion of refractive index has been studied in terms of Wemple – Di Domenico model. The value of static refraction index has been found to increase with Te content. The distribution of the possible chemical bonds has been calculated. The obtained results were correlated with the character of the chemical bond for the prepared compositions through a study of parameters such as average heat of atomization (Hs), the cohesive energies of the bonds (CE), The mean bond energy and average coordination number (m).