Enhanced Performances of n-ZnO Nanowires/p-Si Heterojunctioned Pyroelectric Near-Infrared Photodetectors via the Plasmonic Effect.

Although pyroelectric photodetectors have been intensively studied, the transient temperature change rate of pyroelectric materials is a main restrictive factor for improving the performance. In this work, we fabricate an ultrafast response self-powered near-infrared (NIR) photodetector (PD) based on Au nanoparticles (NPs) coated an n-ZnO nanowires (NWs)/p-Si heterojunction. The local surface plasmon resonance (LSPR) effect generated at the local contacts of Au NPs/ZnO NWs can significantly enhance the transient temperature change rate of the ZnO material to improve the photoresponse performances of the NIR PD. Compared with that in the pristine ZnO-based PD, the response time of the Au-coated NIR PD is decreased from 113 to 50 μs at the rising edge and 200 to 70 μs at the falling edge. Optical responsivity and detectivity of the Au-coated ZnO-based PD are increased by 212 and 266%, respectively. The pyroelectric current gain is produced by injecting hot electrons from the LSPR effect of Au NPs into the ZnO material and the thermal energy transfer caused by the photothermal effect of plasmonic Au nanostructure. This work provides an in-depth understanding of plasmonic effect-enhanced pyroelectric effect and presents a unique strategy for developing high-performance NIR photodetectors.