Surface plasmon enhanced photoluminescence and Raman scattering of ultra thin ZnO-Au hybrid nanoparticles

Abstract

We report substantially enhanced photoluminescence (PL) and Raman signal from ZnO nanoparticles (NPs) deposited on Si with Au NPs. The resonant excitation of surface plasmon of Au NPs is responsible for the enhanced PL intensity and Raman signal from the ZnO-Au hybrid NPs. Low temperature PL measurements exhibit 14 fold enhancements in the PL intensity of ZnO-Au sample in comparison with ZnO/Si sample. It is found that, at low temperature, the donor bound exciton (DX) has dominant contribution in the PL emission of ZnO-Au hybrid NPs. At high temperature, the free exciton (FX) has dominant contribution in PL emission of these NPs. The thermal activation energies of DX and FX are found to be 5 meV and 50 meV, respectively. The defect related visible PL emission of ZnO is completely suppressed in the ZnO-Au hybrid NPs.