Tunable band gap, CB and VB positions of multicomponent Se65-xTe20Ge15Snx chalcogenide glassy systems: Effect of metallic additives on physical and optical parameters

Abstract

In the present communication, the compositional dependency on physical, and optical properties of chalcogenide Se65-xTe20Ge15Snx (x = 5, 10, 15, and 20 at. wt. %) glassy systems have been studied. A comprehensive evaluation of various physical and optical parameters has been analyzed systematically. The spectroscopic parameters have been determined from the transmittance and reflectance spectra using spectrophotometric measurements in the range of 200 nm–1200 nm. The optical energy band gap of the as-prepared samples has been evaluated by deploying Tauc's plot method and is observed to decrease from 1.28 eV to 0.93 eV, while the calculated Urbach energy is observed to increase from 0.110 eV to 0.208 eV with the increasing content of the metallic additives. By using the Wemple-Di Domenico model, the dispersion parameters of the samples are obtained and discussed comprehensively. An increase in Sn content is found to affect the absorption coefficient, extinction coefficient, refractive index, optical density, skin depth, and optical conductivity of the glassy systems. By using the chemical bond approach the estimated cohesive energy values are found to increase from 45.39 kcal/mol to 46.75 kcal/mol. Moreover, the location of conduction and valence band edge has been estimated to examine the potential of the synthesized samples as a semiconductor device. The analyzed properties make the multicomponent Se–Te-Ge-Sn chalcogenide system, a potential candidate for numerous device applications.