Effect of irradiation duration by gamma rays on optical energy gap of ZnO thin films with thickness (300,1500)Å


In this research, the effect of irradiation duration using gamma-rays on forbidden energy gap of (ZnO) thin films were studied. Two samples of ZnO thin films with thicknesses (300,1500)Å that prepared by chemical spray pyrolysis were irradiated using gamma rays emitted form Cs137 of energy (o.662) MeV and radioactivity 370 kBq. ZnO thin films were evaluated spectrophotometrically before and after irradiation for (30,60,90,1410)minutes. The result showed that the increment in the thickness of non-radiated ZnO thin films led to decrease in the optical energy gap , as well as, the increment in the irradiation duration (i.e. irradiation absorbed dose) decreased the optical energy gap values for the two samples because of creation of additional energy levels in the region restricted between valance and conduction bands. The results showed increasing thickness from thin films leads to decreasing in energy gap and decreasing in energy gap with increasing absorbed dose .