Thin films of In2O3/SiO as optical gamma radiation sensors

This paper explores the use of mixed oxide materials such as In2O3 and SiO with various compositions in the form of thermally deposited thin films for gamma radiation dosimetry application. Cs-137 radiation source with an activity of 370 kBq was used for exposing the samples to gamma-radiation. The absorption spectra for as-deposited and gamma-irradiated films were recorded using CARY 1E UV-Visible Spectrophotometer. The values of the optical band gap E-opt were obtained in the view of the Mott and Davis' theory. It was found that the optical properties of thin films were highly affected by composition and manufacturing conditions. For comparison, E-opt of as-deposited thin film with composition 75 wt.% of In2O3 and 25 wt.% of SiO was found to be 0.9 eV, whereas films with 50 wt.% of In2O3 and 50 wt.% of SiO have E-opt=1.15 eV, in all cases assuming indirect allowed transition. It was noted that E-opt decreased with the increase in radiation dose, i.e. the overall disorder of the system has increased. Thin films of In2O3 and SiO mixtures might be regarded as a cost-effective alternative to the existing commercially available radiation detectors.