Gamma-ray induced photo emission from ZnO is investigated for as-grown single crystal wafers at room temperature. The ZnO crystals are irradiated with gamma-ray of 1.17 and 1.33 MeV from a cobalt-60 source. The gamma-ray induced photo emission is analyzed by a charge coupled device equipped spectrometer using the optical fiber cable placed in front of ZnO. In the gamma-ray induced photo emission from as-grown ZnO wafers, the green luminescence (GL) is observed with a peak at around 580 nm in the spectrum around 420 nm–900 nm. The main GL peak is attributed to the singly ionized oxygen vacancy in the as-grown crystal. The emission intensity increases almost in proportion to the wafer thickness when the thickness of the single crystal wafer increases from 0.5 mm to 1.5 mm, suggesting that the gamma-ray induced photo emission is generated in all parts of the crystal due to the strong penetration of gamma-rays. The emission intensity is about 1/60 of gamma-ray induced yellow luminescence from GaN single crystal wafers observed in our previous study [Appl. Phys. Lett. 118 (2021) 032106]. It is suggested that a part of the electrons in the singly ionized oxygen vacancies in ZnO are excited to the conduction band by the Compton electrons generated by the gamma-ray irradiation and oxygen vacancies become the doubly ionized states, reducing their contribution to GL.

研究了室温下生长的单晶晶片的 ZnO 的伽马射线诱导光发射。用来自钴 60 源的 1.17 和 1.33 MeV 伽马射线照射 ZnO 晶体。伽马射线诱导的光发射通过配备有电荷耦合装置的光谱仪使用放置在 ZnO 前面的光纤电缆进行分析。在生长的 ZnO 晶片的伽马射线诱导光发射中，观察到绿色发光 (GL)，在 420 nm–900 nm 的光谱中的 580 nm 附近有一个峰值。主 GL 峰归因于生长晶体中的单电离氧空位。当单晶晶片的厚度从 0.5 mm 增加到 1.5 mm 时，发射强度几乎与晶片厚度成正比，这表明由于伽马射线的强烈穿透，在晶体的所有部分都会产生伽马射线诱导的光发射。发射强度约为我们之前研究中观察到的 GaN 单晶晶片的伽马射线诱导黄色发光的 1/60 [Appl. 物理。莱特。118 (2021) 032106]。这表明 ZnO 中单电离氧空位中的一部分电子被伽马射线照射产生的康普顿电子激发到导带，氧空位变成双电离态，降低了它们对 GL 的贡献。