Sn Addition on Se80Te20-xSnx Glass Alloys, Theoretically Prediction and Experimental Optical Properties of Thin Films

The present article is divided to two parts, the theoretical part study the effect on the physical properties such as average coordination number and fraction of floppy modes with the variation in tin content for Se80Te20-xSnx (x=6, 9, 12, and 15 at.%) glassy alloys. We show that, by taking more Sn content in Se80Te20-xSnx (x=6, 9, 12, and 15 at.%) glassy alloys, it reduces the fraction of floppy modes. The experimental part study the optical properties of ternary glassy of Se80Te20-xSnx (x=6, 9, 12, and 15 at.%) thin films. These thin films of Se80Te20-xSnx (x=6, 9, 12, and 15 at.%) were prepared by the conventional thermal evaporation technique on glass substrate. Optical reflection and transmission spectra of Se80Te20-xSnx (x=6, 9, 12, and 15 at.%) chalcogenide thin films have been obtained in the range 200−2500 nm at room temperature. The absorption coefficient (α) has been determined as a function of Sn content. It was found that the optical band gap decrease with increasing the Sn content. The results are interpreted in terms of the change in concentration of localized states due to the shift in Fermi level as a result of varying of Sn content.