Two-Dimensional/Three-Dimensional Interface-Driven Photocarrier Dynamics in MoSe ₂ /GaTe/ZnGa ₂ O ₄ Heterostructures for Deep Ultraviolet Photodetection

Deep ultraviolet (DUV) photodetectors are vital for a wide range of advanced applications, including space exploration, environmental monitoring, and secure optical communication. However, although conventional oxide-based photodetectors exhibit high responsivity, they often suffer from limited response speed. To address these challenges, we demonstrate a high-performance DUV photodetector based on a 2D/3D heterostructure comprising few-layer MoSe₂ and GaTe, grown via molecular beam epitaxy on a metal-organic chemical vapor deposition-grown zinc gallium oxide (ZnGa₂O₄) layer on a c-plane sapphire template. The crystallinity and structural quality of the as-grown 2D/3D heterostructure were confirmed through in situ RHEED, TEM, XPS, and XRD analyses. The resulting photodetector exhibits a peak responsivity of 216.6 A/W, with a rise time of 2 ms and a decay time of 3 ms under DUV illumination. Both the response speed and responsivity are significantly enhanced compared to devices fabricated solely on ZnGa₂O₄. This improved performance is attributed to efficient interfacial charge transfer and favorable carrier dynamics enabled by the band alignment at the 2D/3D interface. These findings highlight the advantages of integrating 2D-layered materials with wide-band gap oxides, offering a promising pathway toward next-generation, high-speed DUV optoelectronic devices.