Study the Physical Properties of Some Alloy Materials and Effect of Gamma Radiation

Abstract

The present paper reports the effect of replacement of selenium by tellurium on the optical gap and some other physical parameters of new quaternary chalcogenide Te_xGe₂₀Se_(60-x)As₂₀ (x = 0, 10, 15 and 20 at. %) thin films. Thin films with thickness 100 nm of Te_xGe₂₀Se_(60-x)As₂₀ were prepared by thermal evaporation of the bulk samples. Increasing tellurium content is found to affect the average heat of atomization, cohesive energy and energy gap of the Te_xGe₂₀Se_(60-x)As₂₀ alloys. Optical absorption measurements showed that the fundamental absorption edge is a function of composition. The optical absorption is due to allowed direct transition and the energy gap decreases with the increase of tellurium content. The chemical bond approach has been applied successfully to interpret the decrease of the optical gap with increasing tellurium content. it has also been observed that the increase of Te was followed by decrease in glass transition temperature. The prepared films were irradiated by gamma rays at doses up to 200kGy. It was found that the compositions were almost stable against gamma radiation.

Keywords: amorphous, chalcogenide, optical properties.