Some physical properties of GexAsxS1−2x glasses

Bulk glasses GexAsxS1−2x where 0.0833 ≤ x ≤ 0.3 were prepared. The softening temperature of prepared glasses increases while the optical gap decreases with an increase in x. Microcrystalline sulfur was identified in some sulfur rich glasses. In some arsenic rich glasses the gradient annealing experiments indicate presence of arsenic clusters. Raman and infrared spectra show complicated structural arrangement of the glasses namely in the region where x > 0.1818. For example in the narrow region of the chemical composition (0.1818 < x < 0.25) the presence of As4S3 molecular entities was identified. Photo-induced changes of the optical transmission induced by white light indicate maximum in photo-sensitivity for the compositions at around x ≈ 0.1167 and x ≈ 0.225. Gap states and the states related to Urbach edge are suggested to be responsible for observed photo-darkening.