Effect of gamma irradiation on some electrical properties and optical band gap of bulk Se92Sn8 chalcogenide glass

Some electrical properties and optical band gap of un-irradiated and gamma irradiated, at different doses of 4, 20 and 33 kGy, of bulk Se92Sn8 glass have been studied. The I-V measurements, carried out in the temperature range of 187-296 K, have been done at different electric fields and exhibit an ohmic and a non-ohmic behavior at low and high fields, respectively, for both un-irradiated and gamma-irradiated glass. In both cases, the conduction mechanism occurs due to Variable Range Hopping (VRH) of charge carriers in the localized states near Fermi level. As the gamma-doses increase the amorphicity of the glass decreases, as monitored by the disorder parameter T-o, and the density of states N(E-F) increases up to 20 kGy after which a reverse in both parameters is observed. The increase in gamma-doses increase the values of the allowed indirect optical band gap E-g of Se92Sn8 glass up to 20 kGy after which E-g decreases but remain higher than that of un-irradiated glass. (C) 2010 Elsevier B.V. All rights reserved.