Physical and optical characterizations of Ge10Se90 − xTex thin films in view of their spectroscopic ellipsometry data

Abstract

Ge10Se90−xTex (x=10, 20, 30) alloys have been prepared by the conventional melt quenching technique. Several important physical parameters have been calculated to understand the structural changes in the prepared compositions. Spectroscopic ellipsometry technique has been used to investigate the optical properties of the deposited thin films. The extracted optical constants have been utilized to evaluate several interesting optoelectrical parameters. The prepared films have revealed indirect energy gap transition that varied from 1.4 to 1.02eV. Increasing Te content leads to the increase in the joint density of states (JDOS) in the investigated films which is accompanied by the decrease in the energy gap. Profound analysis has been made to study the variation of physical, optical, and optoelectrical parameters of Ge10Se90−xTex as a function of Te content. Moreover, it was fruitful to estimate the changes in the nonlinear parameters of the studied films. An obvious increase in the nonlinear parameters has been observed with the increase in Te percent. This refers to an increase in the nonlinear response of bound electrons in the glassy system to the applied electric field. Believing this we may expect the usage of the samples under investigation in non-linear devices. The studied parameters have enriched our current knowledge regards to the nature of the studied compositions.