Coupling of photoluminescent centers in ZnO to localized and propagating surface plasmons

Abstract: The interaction of excitons and other photoluminescent centers in semiconductors with plasmons represents the coupling of the fundamental one-particle, electron-hole excitation with the fundamental many-particle excitation in metals. We describe recent photoluminescence and pump-probe experiments that illustrate both the energetics and the dynamics of this interaction, in a model material incorporating ZnO films separated from a nanostructured plasmonic metal substrate by a variable-thickness spacer layer. We find evidence for different coupling mechanisms for the band-edge exciton and donor–acceptor pair defect luminescence, and discuss the competing roles of localized surface-plasmon resonances and propagating surface-plasmon polaritons. We also present first femtosecond pump-probe lifetime measurements for the band-edge exciton with and without the presence of nearby metal nanostructures. [Copyright &y& Elsevier]