Effect of excitation intensity and surface morphology on the photoluminescence of ZnO films under the influence of surface plasmon resonance

It was observed that luminescence enhancement in Ag-treated ZnO polycrystalline (friable) films occurs under low pumping, while luminescence quenching plays the main role under high pumping intensity. For the explanation of this phenomenon an assumption about the occurrence of losses in the system was made. At the same time it was observed that on the Ag-coated epitaxial (dense) ZnO films only luminescence quenching can be seen independently of pumping level that evidently indicates that the roughness of ZnO films is required for the luminescence enhancement of ZnO films treated with Ag.