Study of radiation effect and bismuth content on the physical properties of some chalcogenides based on selenium

A series of Ge 18 Bi x Se 82−x (x = 0.5, 2, 4, 6 & 8) thin films were prepared using thermal evaporation on glass substrates. The structural, optical and electrical properties of the prepared samples were investigated. The samples were exposed to γ -ray of 60 Co source with gradually increased doses up to (150 kGy). The changes of the properties of the irradiated samples have been studied. Single oscillator and Drude models were used to describe the dispersion region. The changes of the optical parameters such as optical energy gap (E op ), Urbach energy (E u ), and the plasma frequency ( ω p ) due to gamma irradiation were studied. The results obtained were explained in terms of the interaction of radiation with matter. The electrical conductivity was studied for both the as-prepared and irradiated films revealing negative differential conductance behavior.