Mechanism of the enhancement and quenching of ZnO photoluminescence by ZnO-Ag coupling

¹ Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University Wuhan 430072, PRC
² Center for Electron Microscopy and School of Physics and Technology, Wuhan University - Wuhan 430072, PRC

^a fren@whu.edu.cn
^b czjiang@whu.edu.cn

Received: 24 October 2010
Accepted: 14 February 2011

Abstract

New nanostructural composites consisting of Ag nanoparticles (NPs)-SiO₂-ZnO films were fabricated by depositing ZnO films on silica substrates which had already been implanted by Ag ions at different energies and fluences. The photoluminescence (PL) emission of ZnO films from these nanostructural composites can be enhanced or quenched comparing to that of a ZnO film directly deposited on bare silica substrate. The enhancement of the band gap emission is ascribed to the local field enhancement induced by the resonant coupling between the excitons of ZnO and the surface plasmons (SPs) of Ag NPs, while the quenching is due to the electron transfer from ZnO to Ag NPs. Our results can be used to clarify the ambiguity in controlling the light emission enhancement and quenching of a semiconductor coupled with the SPs of metal NPs, which is very important for the design and applications of semiconductor and metal coupling to highly efficient optoelectronic devices, biosensor, etc.