Influence of High-Dose 80 MeV Proton Irradiation on the Electronic Structure and Photoluminescence of β-Ga 2 O 3

β-Ga 2 O 3 is regarded as one of the best materials for application in deep space exploration; thus, research on β-Ga 2 O 3 -related radiation damage is necessary for the use of devices in harsh environments. The present work explored the effects of 80 MeV high-energy proton irradiation on β-Ga 2 O 3 single crystals with fluence of 4 × 10 13 cm −2 and 1 × 10 14 cm −2 . X-ray photoelectron spectrometry (XPS) and ultraviolet photoelectron spectrometry (UPS) measurements demonstrated that before proton irradiation, the Fermi level was pinned at the mid-gap energy level due to the existence of native oxygen and gallium vacancy defects. After proton irradiation, gallium and oxygen vacancies increased with irradiation fluence, resulting in the reduction of the bandgap of β-Ga 2 O 3 . Proton irradiation of β-Ga 2 O 3 at 80 MeV is more likely to produce oxygen vacancies; hence, the Fermi level shifts upward to the conduction band. In addition, the UV photoluminescence emission at 3.29 eV is greatly enhanced with irradiation fluence. These results will be helpful for the design of UV devices. Graphical Abstract