[MoB3] Crystal Growth & Characterization of Oxides

3:15 PM - 3:30 PM JST(6:15 AM - 6:30 AM UTC)

[MoB3-05] Polarity- and Annealing-Dependent Scintillation Properties of Hydrothermally Grown c-Plane ZnO Single Crystals

〇Takami Abe¹, Toshiaki Kunikata², Shota Otake², Haruaki Ezawa², Yusuke Endo², Takayuki Yanagida² (1. Iwate Univ. (Japan), 2. NAIST (Japan))

Zinc oxide (ZnO) is a promising scintillator for α-particle detection owing to its wide bandgap (3.37 eV), high optical transparency, and density of 5.6 g/cm³. Due to polarity along the c-axis, hydrothermally grown ZnO forms two distinct growth regions: the +c region with a Zn-terminated surface and the −c region with an O-terminated surface. In this study, multiple c-plane substrates were cut from a single crystal, covering the −c side, the seed-crystal vicinity, and the +c side, to systematically evaluate the effects of growth polarity and thermal annealing on scintillation properties. Pulse-height spectra under ²⁴¹Am α-ray irradiation and X-ray-induced luminescence (XRL) spectra were measured before and after annealing at 1000 °C for 2 h in air. After annealing, c-plane substrates from the +c growth region showed a remarkable enhancement of near-band-edge emission in XRL spectra. In particular, a substrate from the near-surface area of the +c region exhibited an approximately 20-fold increase in light yield compared with that before annealing. These results demonstrate that thermal annealing significantly enhances scintillation light output in the +c growth region by promoting near-band-edge emission.