Ultrafast Self-Powered Solar-Blind Ultraviolet Photodetector Based on Ga2O3 Microwire/GaN p-n Heterojunction Using a Single-Layer Graphene as Electrode

Solar-blind ultraviolet (UV) photodetectors (PDs) with high sensitivity and rapid photoresponse time are indispensable for practical applications in medical imaging diagnostics, military surveillance, advanced manufacturing, and other fields. This study presents a high-performance self-powered solar-blind UV PD, which is based on a gallium oxide (Ga2O3) microwire (MW)/gallium nitride (GaN) p-n heterojunction, with a single-layer graphene employed as the top electrode. The device showcases excellent rectification and photovoltaic characteristics, with an open-circuit voltage of 1.95 V, establishing it as a remarkable self-powered detector. When illuminated by a 265-nm light at 0-V bias, the device demonstrates a responsivity of 108.7 mA/W, a specific detectivity of {4.2} \times {10}^{{12}} Jones, and an external quantum efficiency of 51.0%. Remarkably, the device exhibits an extremely fast response speed, with the rise/recovery times of 88.2/ 85~\mu s, and the response bandwidth is estimated to be 3.5 kHz. Furthermore, our exploration of utilizing the detector as an optical data receiver in optical communications enabled to produce promising results, indicating its forward-looking applications for solar-blind UV detection. This study offers a simple and practical method for developing high-performance self-powered solar-blind UV PDs using low-dimensional Ga2O3 single crystal, providing valuable insights for advancing research in optoelectronic devices that function without external power sources.