LOW TEMPERATURE SCINTILLATION PROPERTIES OF Ga2O3

This work is devoted to the study of the luminescence and scintillation properties of an undoped Ga2O3 crystal over the 7-295 K temperature range. The samples were obtained using the edge-defined film-fed growth method. These investigations were performed in order to confirm that the investigated crystals really could be considered as promising scintillation detectors of ionising radiation. The steady-state X-ray luminescence was excited by a URS-55A X-ray tube with a Nu-anticathode tube. For the measurements of scintillation characteristics the crystal was placed in a helium constant flow cryostat and excited by alpha-particles from an Am-241 source. Two emission bands observed in UV and blue spectral range are assigned to the radiative recombination of self-trapped excitons and donor-acceptor pairs, respectively. The scintillation light output of the crystal increases with cooling, reaching the maximum value of 19300 +/- 2200 ph/MeV at 50 K, and then it decreases by 30 % with further cooling to 7 K. It has been found that at room temperature an undoped Ga2O3 exhibits about one-third of the light output of a commercial LYSO-Ce scintillator. The detection efficiency of the crystal is lower in comparison with the best scintillators in the field. Nevertheless, taking into account the fact that the intrinsic defects play a major role in the emission of gallium oxide, we can predict that substantial improvement of the scintillation properties is likely to occur through the material doping and optimisation of the production technology. This finding evidences that undoped beta-Ga2O3 can be used for scintillation detection over the wide temperature range. The measured kinetics of the luminescence decay possesses a recombination character with the corresponding decay time (tau(0.1)), increasing from 1 to 1.8 x 10(-6) s with cooling.