A self-powered ultraviolet photodetector based on a Ga ₂O ₃/Bi ₂WO ₆ heterojunction with low noise and stable photoresponse

A self-powered solar-blind ultraviolet (UV) photodetector (PD) was successfully constructed on a Ga ₂O ₃/Bi ₂WO ₆ heterojunction, which was fabricated by spin-coating the hydrothermally grown Bi ₂WO ₆ onto MOCVD-grown Ga ₂O ₃ film. The results show that a typical type-I heterojunction is formed at the interface of the Ga ₂O ₃ film and clustered Bi ₂WO ₆, which demonstrates a distinct photovoltaic effect with an open-circuit voltage of 0.18 V under the irradiation of 254 nm UV light. Moreover, the Ga ₂O ₃/Bi ₂WO ₆ PD displays excellent photodetection performance with an ultra-low dark current of ∼ 6 fA, and a high light-to-dark current ratio (PDCR) of 3.5 × 10 ⁴ in self-powered mode (0 V), as well as a best responsivity result of 2.21 mA/W in power supply mode (5 V). Furthermore, the PD possesses a stable and fast response speed under different light intensities and voltages. At zero voltage, the PD exhibits a fast rise time of 132 ms and 162 ms, as well as a quick decay time of 69 ms and 522 ms, respectively. In general, the newly attempted Ga ₂O ₃/Bi ₂WO ₆ heterojunction may become a potential candidate for the realization of self-powered and high-performance UV photodetectors.