Interface-engineered p-CsCu2I3/n-Ga2O3 nanowire heterojunctions for self-powered ultraviolet photodetection

Abstract

Self-powered ultraviolet photodetectors based on semiconductor heterojunctions are attractive for low-power optoelectronic systems, yet their performance is often limited by interfacial recombination and inefficient carrier separation. Herein, we report an all-inorganic p-CsCu₂I₃/n-Ga₂O₃ nanowire heterojunction self-powered photodetector with a continuous spectral response spanning from UVA to UVC fabricated via pulsed-laser deposition and thermal evaporation, in which an ultrathin CuI interlayer is introduced as an interfacial engineering layer. The Ga₂O₃ nanowire network provides a large junction area and efficient carrier transport pathways, while the CsCu₂I₃ layer serves as the p-type partner, offering a combination of good stability and a suitable bandgap for UV response. The incorporation of the ultrathin CuI interlayer as an interface engineering tactic proved crucial, significantly boosting key device metrics including photocurrent, on/off ratio (∼630), responsivity (120.3 mA W⁻¹), detectivity (1.50 × 10¹² Jones), and response speed (21/24 ms) under 320 nm, 103 µW cm⁻² illumination. This work demonstrates a robust, lead-free, all-inorganic heterojunction platform and highlights the importance of interfacial regulation in the development of low-power, multi-spectral and stable self-powered UV photodetectors.