Enhanced self-powered UV sensing performance of ZnO/Au/Al₂O₃ photodetector with the decoration of Au nanoparticles

In this work, self-powered ZnO/Au/Al₂O₃ photodetectors (PDs) with enhanced UV sensing performance were successfully fabricated. The effects of Au nanoparticles on optical and photodetect ability of ZnO/Au/Al₂O₃ nanorods were studied in detail. The results showed that the ZnO nanorods exhibited enhanced UV emission and reduced visible emission after the Au decoration. The best UV sensing performance was achieved from the ZnO/Au/Al₂O₃-based PD, of which the size of the Au nanoparticles and the thickness of the Al₂O₃ were 3–4 nm and 6 nm, respectively. The on/off ratio, UV sensing responsibility, and detectivity were 805, 6.8 mA/W, and 1.7 × 10⁹ Jones, respectively, which were 8.5, 8.6, and 8.5 times to that of ZnO/Al₂O₃-based PD without Au nanoparticle decoration (@ light intensity of 0.6 mW/cm²; 0 bias). It was believed that the surface plasmonic effect, carrier confinement, and the surface passivation co-contributed to the enhanced UV photodetect ability. The work may provide an insight into the design and synthesis of 1D nano-material-based self-powered UV detectors for next-generation low cost, large area, and energy-efficient optoelectronic devices.