Surface-plasmon-enhanced band-edge emission and lasing behaviors of Au-decorated ZnO microstructures

We demonstrate that the intensity of the band edge emission and lasing threshold from ZnO microstructures can be improved via the surface plasmon effect of Au nanoparticles. The near-band-edge emission can be enhanced by 11 fold and the defect-related emission is completely suppressed due to the electron transfer between the conduction band and defect levels through the localized surface plasmon resonance. The results suggest that Au nanoparticles can effectively enhance the lasing characteristic by turning down the lasing threshold, which is attributed to the resonance coupling between the surface plasmon and the optical transition in ZnO. In addition, the formation of superior scattering species by Au nanoparticles play another important role in the random lasing mechanism.