Emission enhancement from metallodielectric-capped ZnO films

Emission enhancement from ZnO thin films coated with Al/AlOx has been studied by photoluminescence spectroscopy. While Al exhibits a moderate enhancement on ZnO, the introduction of an ultrathin AlOx spacer can increase the luminescence significantly. By examining the dependence of light emission of Al/AlOx/ZnO on AlOx thickness, we found, other than the surface plasmon mediation, a short-ranged nonradiative channel that plays a crucial role in determining that the overall emission enhancement is also present. Based on a simple analytical model, it is found that the nonradiative process is strongly dependent on (AlO(x)thickness)(-6) and therefore its origin is suggested to be of Forster type. Finally, an AlOx spacer with thickness of 5 nm is found to be adequate to eliminate the unwanted quenching effect. (c) 2006 American Institute of Physics.