Solar‐blind ultraviolet photodetector based on graphene/vertical Ga ₂ O ₃ nanowire array heterojunction

In this paper, a solar‐blind ultraviolet photodetector (PD) based on the graphene/vertical Ga 2 O 3 nanowire array heterojunction was proposed and demonstrated. To the best of our knowledge, it is the first time that vertical Ga 2 O 3 nanowire arrays have been realized. Ga 2 O 3 nanowires were obtained by thermally oxidizing GaN nanowires grown by molecular beam epitaxy on n‐doped Si substrate. Then, a monolayer graphene film was transferred to Ga 2 O 3 nanowires to form the graphene/vertical Ga 2 O 3 nanowire array heterojunction and transparent electrodes. The fabricated device exhibited a responsivity (R) of 0.185 A/W and rejection ratio (R258 nm/R365 nm) of 3×10 4 at the bias of −5 V. Moreover, the fast response times of this PD were 9 and 8 ms for the rise and decay times under 254 nm illumination, respectively, which are attributed to the unique properties of nanowire arrays and the graphene/vertical Ga 2 O 3 nanowire array heterojunction structure.