Research On The Surface-plasmon-mediated Emission Enhancement Characteristics From Two Types Of Sandwich Structures:ZnO/Ag/ZnO And Ag/ZnO/Ag

The optical properties of the metal nano-particles and its application of surface enhanced fluorescence is a focus of research on the nanoscale science and technology. It has been an effective way to enhance photoluminescence from light-emitting materials and devices by the resonant interaction between free charges of metal and light emitted from materials. In this paper, we mainly studied the advantage of two novel sandwich coupling system:ZnO/Ag/ZnO/Si and Ag/ZnO/Ag/Si in photoluminescence enhancement over the two common coupling systems:Ag/ZnO/Si and ZnO/Ag/Si. We further discussed the effect and mechanism of surface plasmon in the photoluminescence enhancement and quenching of semiconductor material.We fabricated the ZnO/Ag/ZnO/Si sandwich structure on the basis of Ag/ZnO/Si bi-layer structure, consequently, the intensity of photoluminescence was further enhanced. Then we studied the changing curve of photoluminescence enhancement factor of ZnO/Ag/ZnO/Si sandwich structure and Ag/ZnO/Si bi-layer structure by varying the growth time of Ag. In contrast to Ag/ZnO/Si bi-layer structure, ZnO/Ag/ZnO/Si sandwich structure makes full use of the local field arising from sandwiched Ag layer, so sandwich structure is more advantageous in photoluminescence enhancement, and the maximum enhancement factor of sandwich structure is 5.5 times than that of Ag/ZnO/Si bi-layer structure.We fabricated the Ag/ZnO/Ag/Si sandwich structure on the basis of ZnO/Ag/Si bi-layer structures, consequently, the intensity of photoluminescence was further enhanced. Then we studied the changing curve of photoluminescence enhancement factor of Ag/ZnO/Ag/Si sandwich structure and ZnO/Ag/Si bi-layer structure by varying the growth time of Ag. In contrast to ZnO/Ag/Si bi-layer structure, Ag/ZnO/Ag/Si sandwich structure is more advantageous in photoluminescence enhancement because of the strong local field in ZnO layer arising from the interaction between two Ag layers, and the maximum enhancement factor of sandwich structure is 2 times than that of ZnO/Ag/Si bi-layer structure.At last, through the contrast research between ZnO/Ag/ZnO/Si and Ag/ZnO/Ag/Si two sandwich structures, we found that because of the competition between the photoluminescence quenching owing to the charge transfer and the photoluminescence enhancement due to the surface plasmon, when growth time of Ag is less than 15 seconds, ZnO/Ag/ZnO/Si sandwich structure is more advantageous in photoluminescence enhancement, when growth time of Ag is more than 30 seconds, Ag/ZnO/Ag/Si sandwich structure is more advantageous in photoluminescence enhancement.