Temperature dependence of surface plasmon mediated emission from metal-capped ZnO films

Surface plasmon (SP) mediated emission from Al-capped ZnO films has been studied by temperature-dependent photoluminescence from 10to300K. By comparing with bare ZnO, it is found that the SP induced emission enhancement ratio linearly decreases with increasing temperature. By taking into account temperature-dependent dielectric functions of both Al and ZnO, theoretical Purcell factor has been calculated for different temperatures. We find the experimental results are highly consistent with theory. From the calculation, we have found the increase of plasmonic density of states with decreasing temperature is the primary cause for the increase of SP coupling.