Zero-biased deep ultraviolet photodetectors based on graphene/cleaved (100) Ga₂O₃ heterojunction

Abstract

In this paper, fast response, zero-biased, solar-blind UV photodetectors based on graphene/β-Ga₂O₃ heterojunctions were fabricated by transferring a monolayer graphene onto fresh cleaved β-Ga₂O₃ (100) single crystal substrate. At zero bias, the photo responsivity at 254 nm and the UV/visible rejection ratio (R₂₃₅ nm/R₄₀₀ nm) and the response time are obtained to be 10.3 mA/W and 2.28 × 10² and 2.24 μs, respectively, for the graphene/β-Ga₂O₃ (100) detector. The fast response and the high sensitivity can be attributed to the high mobility and UV transparency of graphene top-electrode and the low defect density of the β-Ga₂O₃ (100) cleaved surface. Such zero-biased detectors are very promising for next-generation solar-blind UV photodetection.