Passivation engineering enhanced photodetection in β-Ga2O3 deep ultraviolet photodetectors

Abstract β-Ga2O3 has gained significant attention for deep ultraviolet (DUV) photodetection applications due to its ultra-wide bandgap (>4.8 eV). However, surface and interface states have impeded the achievement of high responsivity in β-Ga2O3 photodetectors. In this study, an Al2O3 passivation layer is introduced to mitigate the recombination processes in β-Ga2O3 photodetectors. The optimized device, termed the metal–insulator–semiconductor-insulator-metal photodetector (MISIM PD), exhibits exceptional DUV photodetection performance. The responsivity, detectivity, photo-to-dark current ratio, and both static and dynamic characteristics of the MISIM PD are compared with those of a conventional metal-semiconductor–metal (MSM) architecture. The MISIM PD achieves increases of up to 264.18% in responsivity, 482.86% in detectivity, and 853.14% in photo-to-dark current ratio. The measured photocurrent linearity, photo-absorption, and response time indicate a reduction in recombination centers, attributed to the passivation effect of Al2O3. Additionally, DUV imaging with the MISIM PD further underscores the advantages of Ga2O3-based photodetectors.