Enhancement in NH3 sensing performance of ZnO thin-film via gamma-irradiation

In this work, chemically synthesized Zinc Oxide (ZnO) thin films were exposed to Cobalt-60 (Co- 60), 1.25 MeV average energy of gamma source at different doses for possible augmentation in NH3 sensing. The hexagonal crystalline structure was confirmed by XRD spectra and an enhancement in crystallite size was observed with an increase in radiation followed by decrease at 50 kGy dose. The FTIR spectra showed there were no significant changes in the peak position after gamma-irradiation. The morphological investigation showed the maturation of 1D ZnO hexagonal nanorods over the surface of the film. However, after gamma-irradiation, the ZnO nanorods were found connected, forming bunches. The band-gap increased for 50 kGy doses as compared to pristine ZnO thin film. However, characterization result analysis showed that gamma-irradiation produced conspicuous improvements in chemically prepared ZnO microstructure. It was found that post-irradiated (at 30 kGy) ZnO thin film sensor achieved 7.29 as response factor for 400 ppm NH3 gas sensing compared to 1.01 for the pristine sample. The outcome of this study showed that gamma-irradiation is an effective technique for improvement in the sensing performance of ZnO thin films which has great potential to use gamma irradiated ZnO sensor in chemical industries and laboratories. (c) 2020 Elsevier B.V. All rights reserved.