Impact of exciton dissociation on the metal-enhanced photoluminescence in ZnO/ZnMgO multiple quantum wells

摘要

We have investigated metal-enhanced excitonic emission from ZnO/ZnMgO multiple quantum wells (MQWs) grown by molecular beam epitaxy. Capping of Al nanoparticles results in ～1.5-fold enhancement of photo-luminescence (PL) at room temperature. Temperature-dependent PL analysis suggests that exciton dissociation acts as an additional non-radiative recombination channel when the MQWs are capped with metal. The non-radiative recombination rate is found to be larger than the radiative one by ～21-fold. This explains the relatively low enhancement ratio of PL although significant surface plasmon coupling is present.