Using the Surface Plasmon Resonance of Au Nanoparticles to Enhance Ultraviolet Response of ZnO Nanorods-Based Schottky-Barrier Photodetectors

Surface plasmon resonance mediated by Gold (Au) nanoparticles (NPs) was employed to enhance the ultraviolet (UV) response of ZnO nanorod (NR)-based Schottky-barrier photodetectors (SB-PDs). The defect-level emissions of ZnO NRs induce surface plasmon resonance in Au NPs and enhance the electromagnetic field near Au NPs, which excites a great deal of electrons from Au NPs crossing over the barrier height of Au NP/ZnO interface. This causes the band-to-band emission of ZnO (384 nm) is increased by a magnitude of three, and the deep-level emissions (450-700 nm) are drastically decreased as compared to ZnO NRs without coverings of Au NPs. Also, it drastically enhances the UV (340 nm)-to-visible (560 nm) rejection ratio from 115 to 443. The effect of surface plasmon resonance is verified by that the responsivity of SB-PD with the covering of Au NPs exhibits a greater increasing with applied reverse-bias voltage than that without Au NPs.