γ-Radiation dosimetry using screen printed nickel oxide thick films

Thick films of Nickel oxide (NiO) were investigated for γ-radiation dosimetry purposes. Samples were fabricated using the thick film screen printing technique. Absorption spectra for NiO films were recorded and the values of the optical band gap for as-printed, irradiated and annealed films were calculated. It was found that the optical band gap value decreased as the radiation dose was increased. Samples with an Ag-NiO-Ag sandwich structure were exposed to a 60Co γ-radiation source at a dose rate of 6 Gy/min. The relative change in current increased linearly with increased dosage up to 720 Gy. The I-V characteristics indicated a Poole-Frenkel conduction mechanism. It was found that annealing restored both the electrical and the optical properties of the samples.