High Gain, Low Voltage Solar-Blind Deep UV Photodetector Based on Ga₂O₃/(Al_xGa_1-x)₂O₃/GaN nBp Heterojunction

In this study an (Al_xGa_1-x)₂O₃ barrier layer is inserted between β-Ga₂O₃ and GaN in a p-GaN/n-Ga₂O₃ diode photodetector, causing the dark current to decrease considerably, and device performance to improve significantly. The β-Ga₂O₃/β-(Al_xGa_1-x)₂O₃/GaN n-type/Barrier/p-type photodetector achieves a photocurrent gain of 1246, responsivity of 237 A W^-1, and specific detectivity of 5.23 × 10¹⁵ cm Hz^1/2 W^-1 under a bias of -20 V. With the irradiation of 250 nm solar-blind ultraviolet light, the photocurrent exhibits a dramatic nonlinear increase beyond a bias of ≈-4 V, attributed to interband electron tunneling. The onset of interband tunneling at a relatively low bias is due to the strong internal electric field formed by self-trapped holes (STHs) in Ga₂O₃. This study also proposes an effective way to suppress persistent photoconductivity and significantly increase the device operation speed in photodetectors fabricated from Ga₂O₃ through the light-induced neutralization of STHs.