STUDIES ON RADIATION INDUCED EFFECTS IN METAL OXIDE THIN FILMS

Abstract

Studies oii gaiiiiiia radiation ill(lli(ed cilects in electrical and optical properties of, thin films of metal oxides have been gaining increasing attention, due to their extensive use in real time garnnia radiation dosimetry. This work aims to study he electrical and OptiCal properties of metal OXIdeS thin films l.Ifl(ler the influence of gamma rays by using tliiii films of different metal oxides and their mixtures. The report describes the variation in various properties of Zinc Oxide, Telluriuni !)ioxide. and Indium Oxide thin films exposed to gamma radiation using 60Co and t37Cs sources. The oj)t.ical characterization of the aS-deposite(l thin films as well as ganima irradiated thin films clearly show that the optical band gap c1ecreases with increase in the gamma radiation dose up to a certain limit. however, the ol)tica1 band gap has been fbumal to increase beyond this limit. * The current-voltage characteristics for the as-(lcposited and gamnmiia irradiated thin films were analysed to obtain current density versus close l)lOtS at different applied voltages. The plots obtained clearly show that time current density increases alnmost liiiearlv with the radiation close up to ccrt:ain limit and this limit is found to be dependent on thickness of the thin film and rnateria.l to be used. Beyond this limit the current density is found to decrease. The increase in the current is due to the lowering of the optical band gap and the decrease iii the current after certain limit can be attributed to the rising of the optical band gap and the formation of the clusters. Studies have also been carried out for time mixture of tellurium dioxide and indium oxide The observed changes in electrical properties clearly indicate the increase iii sensitivity for metal oxide mixtures.