Investigation of enhanced ultraviolet emission from different Ti-capped ZnO structures via surface passivation and surface plasmon coupling

Photoluminescent properties from three types of Ti and TiO2 capped ZnO structures have been investigated with different surface/volume ratios. Interestingly, it was found that both of surface passivation and surface plasmon (SP) coupling could affect the enhancements of ultraviolet (UV) emissions in the Ti-capped ZnO, while the enhancement rates of UV emissions via SP coupling were much higher than those via surface-passivation modulation with the increasing surface/volume ratios. Upon the evaluation of the dependence of Purcell factor and electron densities, our results can be well explained through energy transfer between defect-related and SP-coupling emissions.