The Enhanced Raman Scattering from Ag Nanoball/ZnO Hollow Nanosphere Arrays Fabricated by Laser-Induced Annealing

In this work, a facile method was presented to produce Ag nanoball (NB)/ZnO hollow nanosphere (HNS) hybrid structure. Large scale, two-dimensional (2D) ZnO HNS arrays were fabricated on sapphire substrates using the polystyrene (PS) nanospheres as the template. Ag film were deposited on ZnO HNS arrays by radio frequency (RF) magnetron sputtering and then aggregated into Ag NBs on the top of ZnO HNS by the laser irradiation treatment. The size and distribution of Ag NB arrays were controlled by employing different ZnO HNS supporting structure templates. The scanning electron microscopy (SEM) was applied to visually study the evolution process of Ag NB/ZnO NHS arrays. X-ray diffraction (XRD) was carried out to characterize crystal structures of the samples. Obvious surface enhanced Raman (SERS) signals were observed from the Ag NB/ZnO NHS nanocomposite structure compared with that in the ZnO HNS structure by using the R6G as the testing agent. Theoretical simulation results demonstrate that the Raman enhancement originates from the significant enhanced local electromagnetic field induced by the surface plasmon resonance (SPR) of Ag NBs.