GaN/Sn:Ga 2 O 3 Nanowire Network n–n Heterojunction for High-Photocurrent Self-Powered Solar-Blind Photodetection

Solar-blind ultraviolet (UV) photodetectors are critically important for applications such as flame sensing, missile warning, and space communications. These applications exploit the solar-blind background in the near-earth atmosphere, where the ozone layer strongly absorbs solar UV-C radiation (200–280 nm), creating an environment with inherently low background noise. To achieve high-performance detection under such weak signal conditions, we present a self-powered detector architecture based on a band-offset engineered n–n heterojunction. The device was fabricated by directly growing a network of Sn-doped Ga 2 O 3 nanowires on a GaN substrate via chemical vapor deposition (CVD), forming a heterostructure with patterned electrodes. Under 254 nm illumination (82 μW/cm 2 ), the device demonstrates exceptional performance: a photocurrent of 14.57 μA, a responsivity of 5.66A/W, an external quantum efficiency (EQE) of 2762%, and a high photo-to-dark current ratio (PDCR) of 8830. Moreover, the detector exhibits a specific detectivity ( D *) of 4.36 × 10 13 Jones, a fast response time below 50 ms, an ultralow dark current of 1.65 nA, and excellent operational stability. The superior performance is attributed to two key design features: the favorable band alignment at the GaN/Sn:Ga 2 O 3 interface, which promotes efficient carrier separation through a strong built-in electric field originating from the large conduction band offset (Δ E c ≈ 1.36 eV), and the light-trapping effect of the nanowire network architecture, which enhances photon absorption. The powerful built-in electric field further enables effective self-powered operation without external bias, making this architecture highly suitable for low-power and portable solar-blind detection systems.