Self-powered NiO/κ-Ga2O3 heterojunction photodiode for fast broadband ultraviolet (UV) radiation detection

A novel broadband p-n UV photodiode is presented, that integrates an ultrawide band gap n-type κ-Ga2O3 epitaxial film doped with silicon (Si) and a p-type NiO polycrystalline film, to provide a planar NiO/κ-Ga2O3 p-n heterojunction for UV detection applications. The proposed device features a circular design, with a diameter of 240 μm, resulting in compactness and functionality, and represents the first demonstration of broadband UV detection using planar NiO/κ-Ga2O3 photodiodes. It can be operated in self-powered mode, which allows UV detection without use of an external power supply. The p-n photodiode exhibits excellent sensitivity to UVC light and acceptable sensitivity to UVB and UVA radiations. However, the response to UVA light is still weak and requires further optimization of the diode design. Response and recovery time below 0.8 s were observed for all UV illumination range. The presented photodiode has a simple design and shows significant potential in high-performance broadband UV detection in self-powered operation.