Optical and dispersion studies of thin S35-xGe15SnxTe50 films: Assessment of some physical parameters of samples

Abstract

Abstract This article presents a study on the optical and dispersion characteristics of a group of thin films with exciting potential for optical applications. Thermally evaporated a-S35−xGe15SnxTe50 thin films (SGST) where x ranges from 0 to 10 at.% have been investigated. XRD, EDX, and FE-SEM techniques are utilized to examine the samples’ physical properties. Meanwhile, optical characteristics are studied in the 300–2500 nm region through transmission and reflection measurements. Experimental and theoretical methods were employed to determine the optical bandgap energies (Eg), indicating that the films’ electronic transition is indirectly allowed. The Eg-values decreased as Sn-content increased, reaching a range of 1.031 eV to 1.301 eV, while the refractive index increased from 2.513 to 2.741. In addition, the Wemple-Di-Domenico model was used to determine the dispersion energies (Eo and Ed), and it is found that they decreased as Sn-content increased, from 2.014 eV to 2.672 eV for Eo, and from 13.009 eV to 15.334 eV for Ed. Many other important parameters, such as the average heat of atomization, total mean bond energy, and deviation from stoichiometry, are also calculated and discussed. The results of this investigation suggest that these SGST samples could be used in various optical applications and provide a basis for further research and innovation in this exciting field.