A High Responsivity Self-Powered Solar-Blind DUV Photodetector Based on a Nitrogen-Doped Graphene/β-Ga₂O₃ Microwire p-n Heterojunction

A high responsivity solar-blind deep ultraviolet self-powered photodetector (PD) based on a nitrogen-doped graphene (NGr)/ \beta -Ga 2 O 3 microwire p-n heterojunction is reported. Under a 0 V bias and 235 nm (12.2 \mu \text{W} /cm ^{{2}} ) light irradiation, the PD shows a light/dark ratio of \sim 10^{{5}} and a high responsivity of 360 mA/W. Compared with an intrinsic graphene (IGr)/ \beta -Ga 2 O 3 heterostructure, the responsivity and light/dark ratio of the p-n heterojunction under a 0 V bias increases by 28 and 100 times, respectively. Under a −20 V bias, the p-n junction has a significantly low dark current of 1.7 pA, which is 100 times smaller than that of the IGr/ \beta -Ga 2 O 3 device. This is mainly attributed to the increased built-in electric field between \beta -Ga 2 O 3 and NGr. The downwards shift of the Fermi level in NGr (compared to IGr) and the increased depletion region thickness in \beta -Ga 2 O 3 result in the improved performance of the p-n heterojunction PD.