Self-Powered β-Ga2O3 Nanowire via Controlled Sn-Doping and Graphene Interface Optimization Solar Blind Detector for Ultrahigh Photo-To-Dark Current Ratio Deep-UV Detection

Abstract While solar-blind ultraviolet (UV) photodetectors based on gallium oxide (Ga2O3) hold immense potential for weak-signal detection, bare Ga2O3 nanowires frequently suffer from high dark currents and severe surface photocorrosion. To overcome these limitations and achieve ultrahigh zero-bias sensitivity, we engineered a graphene/Sn-doped Ga2O3 nanowire/p-GaN heterojunction. The Sn-doped Ga2O3 nanowires were synthesized via chemical vapor deposition on a p-GaN substrate, followed by graphene interface modification. By systematically optimizing the Sn doping concentration and interfacial contact, the resulting device exhibits outstanding self-powered photoelectric performance under 254 nm illumination (82 μW/cm2). Specifically, at an optimal precursor mass ratio of Ga2O3:diamond/SnO2 = 10:10:7, the photodetector achieves an ultralow dark current of 0.238 pA, an ultrahigh photo-to-dark current ratio of 4.21 × 106, a specific detectivity of 2.5 × 1014 Jones, a responsivity of 0.389 A/W, and an external quantum efficiency of 190%. Additionally, it demonstrates a fast response time (<20 ms) and robust continuous cycling stability over 2400 s. This work presents a highly efficient heterojunction design strategy for advanced self-powered solar-blind UV photodetectors.