[1Ga01-10] Thin Film (TF)

[1Ga02] Effect of gamma irradiation on titanium dioxide thin films as vacuum ultraviolet photoconductive detectors

*Kota Hibino¹, Marilou Cadatal Raduban², Kohei Yamanoi³, Jiˇrí Olejníˇcek⁴, Michal Kohout⁴, Tomoki Kato¹ (1. Department of Physical Science and Engineering ,Nagoya Institute of Technology, 2. Centre for Theoretical Chemistry and Physics, School of Natural and Computational Sciences, Massey University, 3. Institute of Laser Engineering, Osaka University, 4. Institute of Physics, Academy of Sciences of the Czech Republic, Department of Low-Temperature Plasma)

We demonstrate the potential of TiO₂ thin films as photoconductive detectors of VUV radiation. Excitation with a VUV lamp generated a photo current that is at least two orders of magnitude higher compared to the current generated in the dark. Further investigation of the effects of gamma-ray irradiation on the optical properties of TiO₂ confirm the creation of V_O and Ti³⁺ defects, which serve as trapping centers for photo-generated electrons. These traps reduce the effective charge carrier concentration. As a result, gamma-ray irradiation resulted to a decrease in the photo current. Investigation of the optical properties of the irradiated thin films over a period of 720 hours reveal the recovery of its transparency. The photoconductivity of the detector improved after recovery, with the photo current increasing. The photosensitivity also increased by a factor of about 16 post-recovery compared to its photosensitivity before irradiation.