Highly sensitive solar-blind deep ultraviolet photodetector based on graphene/PtSe₂/β-Ga₂O₃ 2D/3D Schottky junction with ultrafast speed

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.