High-performance UV surface photodetector based on plasmonic Ni nanoparticles-decorated hexagonal-faceted ZnO nanorod arrays architecture

We report the photoresponse performance of plasmonic nickel (Ni) nanoparticles (NPs)-decorated ZnO NR arrays-based ultraviolet (UV) surface photodetectors. The ZnO NR arrays were grown on the Si substrate by the facile hydrothermal method, followed by Ni NP decoration on the surface by pulsed laser deposition (PLD) technique. Raman analyses reveal that the grown ZnO NR arrays are in hexagonal wurtzite structure. The field emission scanning electron microscopy (FE-SEM) shows that the grown ZnO NR arrays are vertically aligned, hexagonal faceted, and uniformly distributed on the Si substrate. The 14-fold enhancement in the UV emission upon Ni NP decoration implies the near-field coupling of surface plasmons (SPs) of Ni NPs with the excitons of ZnO NRs. The linear increase in current with the applied voltage indicates good Ohmic contacts between the ZnO NR arrays and the Ag electrodes. The transient photo-response measurements were performed for every twenty seconds (20 s) ON/OFF time and for nine cycles to study its response speed, stability, and repeatability of the photodetectors. The improved photo-response of the Ni NP-decorated ZnO NR arrays is attributed to the near-field coupling of Ni NPs with the underlying ZnO NRs. The decoration of plasmonic Ni NPs provides better optical pathway for the incident light and transfers its hot electrons to the conduction band of ZnO NR arrays gives rise the improved photoresponse.