High-performance β-Ga2O3 solar-blind UV/X-ray photodetector enhanced by oxygen vacancy modulation

Abstract

High-performance solar-blind ultraviolet (SBUV) and X-ray detectors are essential for scientific research, medical diagnostics, and astronomical imaging. Ga₂O₃ has emerged as a promising material for detection in this spectral range. However, the distinct mechanisms underlying SBUV and X-ray detection in Ga₂O₃ remain poorly understood, hindering the optimization of device performance. This study introduces oxygen vacancy modulation to explore these mechanistic differences and enhance comprehensive detection capabilities of Ga₂O₃ detectors. Highly crystalline β-Ga₂O₃ films with different oxygen contents were prepared by metal-organic chemical vapor deposition at various oxygen and trimethylgallium (TEGa) precursor ratios (F_oxy/F_TEGa), and corresponding detectors were then fabricated. As the F_oxy/F_TEGa increases, β-Ga₂O₃ crystal quality improves and oxygen vacancy content decreases. The device based on the film with the lowest oxygen vacancy content exhibits a remarkably low dark current of 30.9 fA. Under SBUV (254 nm), the device demonstrates the photo-to-dark current ratio of 8.7 × 10⁸ and a responsivity of 237 A W⁻¹. Notably, the detector achieves a sensitivity of 10,736 µC cm⁻² Gy_air⁻¹ under X-rays, which is 477 times higher than that of conventional a-Se detectors. Additionally, the study clarifies the differential roles of oxygen vacancies in the photoresponse under SBUV and X-ray irradiation, offering insights into how these differences affect both responsivity and response speed. These findings not only deepen the understanding of the SBUV and X-ray photoresponse mechanisms in Ga₂O₃ detectors, but also provide a stepping stone for the design of detectors with excellent comprehensive performance.