Optical response of gamma irradiated-arsenic selenide thin films

Gamma(γ)-radiation induced effects in thin films of arsenic selenide (As2Se3) were investigated for possible applications in γ-radiation environment and/or γ-radiation dosimetry purposes. Thin film samples were fabricated using thermal evaporation. Optical properties of As2Se3 thin films were studied before and after irradiation. As a result of γ-irradiation, photodarkening of samples was observed for doses up to 104 Gy (10 kGy). Absorption coefficient was found to increase with increase of irradiation dose. Optical energy gap was found to decrease while the localized band tail width was found to increase with dose. SEM was used to examine irradiated films; small nucleation of the crystalline phase could be distinguished. Nucleation increases with dose indicating some local structural changes due to irradiation. Values of absorbance or absorption coefficient in the absorption edge region are suitable control parameters of the proposed dosimeter material. The observed changes in the optical properties suggest that As2Se3 thin film may be considered as an effective material for room temperature real time γ-radiation dosimetry for the relatively high dose industrial applications such as sterilization.