Plasmon-Induced Ag-Decorated ZnO Nanowires for Self-Powered Position Sensing

Abstract

Position-sensitive detector (PSD) is an essential noncontact optical position sensor based on the lateral photovoltaic effect (LPE), which plays a vital role in various applications. However, limited by the absorption of substrate and rapid recombination of carriers, it remains challenging to develop superior-performance PSDs. Here, we use Ag nanoparticles (NPs) to boost the light-harvesting efficiency and ZnO nanowires (NWs) to capture hot electrons and observe the plasmon-enhanced LPE in this structure. Without any applied bias voltage, it shows an excellent position sensitivity in a broad-band range of 405–980 nm with a maximum sensitivity of 252.6 mV/mm, which is about six times larger than that in the ZnO NWs/Si (42.8 mV/mm) structure. Besides, the LPE response is strongly dependent on the ZnO NW growth time and Ag NP concentration. We elaborated the underlying mechanism by analyzing hot electron generation and injection and the diffusion of charge carriers under nonuniform light illumination. The excellent position sensitivity performance can be attributed to the efficient transport of hot electrons in the conductive network of the ZnO NW film. Our findings further establish the potential of Ag-decorated ZnO NWs for noncontact photoelectric sensing and provide insights into developing high-sensitivity, low-cost, and self-powered PSDs.