p-GaSe/n-Ga2O3 van der Waals Heterostructure Photodetector at Solar-Blind Wavelengths with Ultrahigh Responsivity and Detectivity

Ga2O3 with a suitable bandgap width is emerging to be a novel candidate for future optoelectronic applications in the solar-blind region (<280 nm). Herein, solar-blind photodetectors are developed by combining layered GaSe flakes with Ga2O3 epitaxial films, forming a van der Waals pn heterojunction. Photoresponse characterizations indicate that the GaSe/Ga2O3 pn junction is highly sensitive to solar-blind ultraviolet light, with the maximum sensitivity at ∼255 nm. The photodetector demonstrates a particularly high responsivity of 51.9 A/W, a pronounced specific detectivity up to 1014 Jones, and a fast response speed of ∼0.3 ms under ultraweak light illumination. These figures of merit are significantly superior to most of the reported Ga2O3-based photodetectors. This work reveals the great potential of GaSe/Ga2O3 van der Waals heterojunction for developing next-generation, solar-blind photodetectors.