Hybrid self-powered UV photodetector with a sandwich structure of asymmetric interdigitated electrodes

Abstract

We present a novel ZnO/Au/Ti/p-GaN self-powered ultraviolet photodetector (UVPD) featuring a sandwich structure of asymmetric interdigitated electrodes. This unique design skillfully integrates the conventional vertically-structured ZnO/p-GaN UVPD, asymmetric Au/ZnO/Au UVPD, and asymmetric Ti/p-GaN/Ti UVPD into a single device, which effectively enhances the separation and collection efficiency of photogenerated carriers while reducing their composite depletion through the coupling of the built-in electric fields of the Schottky junctions (ZnO/Au, p-GaN/Ti) and the heterojunction (ZnO/p-GaN), creating a synergistic enhancement in performance. At 0 bias, while achieving a fast response speed (0.98/0.63 ms), the ZnO/Au/Ti/p-GaN UVPD also shows improvements in light-to-dark ratios by 7.78, 15.79, and 20.0 times, and in responsivity peaks by 2.7, 4.12, and 152.84 times, compared to the ZnO/p-GaN UVPD, the MSM ZnO UVPD, and the MSM GaN UVPD, respectively. Our proposed sandwich structure of asymmetric interdigitated electrodes offers significant performance enhancement and a simple preparation process, and it can also be applied to other semiconductor heterojunctions, demonstrating wide practical application potential. This work provides a valuable strategy for the development of high-performance and low-cost self-powered UV photodetectors.