Boosting Self-Powered UV Detection in All-Oxide PIN Heterojunctions via Antireflective Nanostructures and Enhanced Interfacial Quality.

Self-powered ultraviolet (UV) photodetectors exhibit broad application potential in fields such as space communication, environmental monitoring, and biological analysis. However, while the internal quantum efficiency of current devices has reached a bottleneck, the external quantum efficiency limited by surface/interface reflection losses still offers considerable room for improvement. Constructing nanostructured antireflective surfaces is therefore a critical strategy to overcome this performance bottleneck. Nevertheless, the fabrication of such nanostructured antireflective layers on many wide-band-gap semiconductors is often constrained by complex processes and the introduction of defects. In this work, a mask-free, room-temperature dilute hydrochloric acid (HCl) solution etching technique is successfully employed to fabricate nanostructured antireflective layers on ZnMgO surfaces, and an all-oxide p-NiO/i-ZnMgO/n-ZnO heterojunction self-powered UV photodetector is constructed. This method not only constructs nanostructures that suppress optical reflection but also optimizes the interfacial properties. The optimized device achieves a peak responsivity of 50.5 mA/W at 295 nm under 0 V bias and a high rectification ratio of 5 × 107 at ±5 V and exhibits a fast response speed. This work provides a simple and effective fabrication strategy for developing high-performance self-powered UV photodetectors.