The correlation of γ-irradiation, particle size and their effects on physical properties of AgInSe2 nanostructure thin films

Abstract

In this work the effect of γ-irradiation on the optical and electrical properties of near stoichiometric AgInSe2 nanostructure thin films have been characterized. The XRD pattern of ingot AgInSe2 powder prepared by solid state reaction showed tetragonal polycrystalline single-phase structure. The thin films of thickness 75nm were prepared by inert gas condensation (IGC) technique at using constant Ar flow and substrate temperature of 300K.Thin films were exposed to annealing process at 473K for 2h in vacuum of 10−2Torr. The amorphous and tetragonal nanocrystalline structures were detected for as-deposited and annealed films respectively by grazing incident in-plane X-ray diffraction (GIIXD) technique. The structure and average particle size of annealed irradiated films by different γ-doses from 0 to 4Mrad were determined using high resolution transmission electron microscope (HRTEM). Optical transmission, reflection and absorption spectra were studied for both annealed unirradiated and irradiated films. Two optical transitions for each annealed unirradiated and film exposed to γ-irradiation doses from 0 to 4Mrad were observed. The evaluated Eg1 due to 1st transition have decreased from 1.52 to 1.44eV and Eg2 due to 2nd transition have decreased from 2.83 to 2.30eV as the particle size increased from 7.3 to 9.5nm by raising the irradiation dose up to 1Mrad. The behavior of d.c. electrical conductivity with temperature that measured under vacuum was examined for all films under investigation. The evaluated activation energies due to irradiation doses are ranging from 0.58 to 0.68eV.