Study of structure and optical absorption in iso-coordinated a-InxSb20 − xAg10Se70 (0 ≤ x ≤ 20) chalcogenide films

Many physical properties the chalcogenide systems strongly depends upon the composition and type of impurity added. In this work, structural and optical properties of thermally evaporated InxSb20 − xAg10Se70 (0 ≤ x ≤ 20) chalcogenide films were studied. Bulk polycrystalline granules were used for the deposition of thin films. XRD studies reveal the amorphous character of the as-prepared films. FESEM images reveal a change in irregular trend in the morphological structures with composition. The EDS spectra show the composition of the as-prepared films is in stoichiometric with the bulk samples. Raman Spectroscopy shows the occurrence of SbSe and SbSb bond vibrations for AgSbSe2 structural units and InSe bond vibrations in AgInSe2 structural units. The optical transmittance and reflectance measurements were used to calculate the absorption coefficient and the indirect optical band gap is found to increases with indium content. The change in film morphology and change in the concentration of molecular units have been used to discuss optical properties with the increase in indium content.