Broadband Ultraviolet Photodetector Based on Vertical Ga2O3/GaN Nanowire Array with High Responsivity

Broadband ultraviolet (BUV) photodetectors responding to the multiband spectrum can effectively reduce false alarm rates and improve the accuracy and versatility of detection systems in various situations. A high-responsivity BUV photodetector based on vertical Ga2O3/GaN nanowire array is proposed and demonstrated. Ga2O3/GaN nanowires are obtained by partially thermally oxidizing GaN nanowires grown by molecular beam epitaxy and used to combine with a monolayer graphene film to form graphene/Ga2O3/GaN heterojunction. Moreover, the oxidation mechanism of GaN nanowires is further investigated by the developed thermal oxidation model. The fabricated devices exhibit excellent performance with a broadband spectral response of exceeding 550 A W-1 at -5 V and a fast-response speed in the millisecond range, which can be attributed to the optical properties of vertical nanowire array structure and the internal gain mechanism of graphene/Ga2O3/GaN heterojunction.