Gamma irradiation study of tin oxide thin films for dosimetric applications

Electrical and optical properties of as-grown and gamma irradiated films of tin oxide, grown on glass substrate by electron beam evaporation at a substrate temperature of 250 deg C have been studied. The as-grown films show conductivity ranging from - 0.02 to - 1 S-cm-1 and the irradiated films show the increment in conductivity value upto - 1.18 S-cm-1. The optical band gap of films has been determined from the transmittance and reflectance spectra in the wavelength range of 400-850 nm at room temperature. The optical band gap of as-grown tin oxide thin film is direct band gap and has a value of - 2.85 eV. Blue shift has been observed in the band gap when exposed to 60 Gy cumulative dose of gamma radiation with a value of - 2.76 eV. XRD analysis has shown that the as-grown films were polycrystalline in nature having crystallite size of 33 nm and there is an improvement in crystallinity and grain size after gamma exposure. This work demonstrates that tin oxide thin films are sensitive to gamma radiation and it can be used for dosimetric applications.