There is an emerging need for high-sensitivity solar-blind deep ultraviolet (DUV) photodetectors with an ultra-fast response speed. Although nanoscale devices based on Ga₂O₃ nanostructures have been developed, their practical applications are greatly limited by their slow response speed as well as low specific detectivity. Here, the successful fabrication of two-/three-dimensional (2D/3D) graphene (Gr)/PtSe₂/β-Ga₂O₃ Schottky junction devices for high-sensitivity solar-blind DUV photodetectors is demonstrated. Benefitting from the high-quality 2D/3D Schottky junction, the vertically stacked structure, and the superior-quality transparent graphene electrode for effective carrier collection, the photodetector is highly sensitive to DUV light illumination and achieves a high responsivity of 76.2 mA/W, a large on/off current ratio of ~ 10⁵, along with an ultra-high ultraviolet (UV)/visible rejection ratio of 1.8 × 10⁴. More importantly, it has an ultra-fast response time of 12 μs and a remarkable specific detectivity of ~ 10¹³ Jones. Finally, an excellent DUV imaging capability has been identified based on the Gr/PtSe₂/β-Ga₂O₃ Schottky junction photodetector, demonstrating its great potential application in DUV imaging systems.

The research of ultraviolet photodetectors (UV PDs) have been attracting extensive attention, due to their important applications in many areas. In this study, PtSe₂/GaN heterojunction is in-situ fabricated by synthesis of large-area vertically standing two-dimensional (2D) PtSe₂ film on n-GaN substrate. The PtSe₂/GaN heterojunction device demonstrates excellent photoresponse properties under illumination by deep UV light of 265 nm at zero bias voltage. Further analysis reveals that a high responsivity of 193 mAdW^-1, an ultrahigh specific detectivity of 3.8 × 10¹⁴ Jones, linear dynamic range of 155 dB and current on/off ratio of ~ 10⁸, as well as fast response speeds of 45/102 njs were obtained at zero bias voltage. Moreover, this device response quickly to the pulse laser of 266 nm with a rise time of 172 ns. Such high-performance PtSe₂/GaN heterojunction UV PD demonstrated in this work is far superior to previously reported results, suggesting that it has great potential for deep UV detection.