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.