SURFACE PLASMON RESONANT ENHANCED OPTICAL TRANSMISSION THROUGH ZNO/AG/ZNO MULTI LAYERED FILMS

The optical transmission enhancement in the visible range through a composite structure, zinc oxide/silver/zinc oxide (ZnO/Ag/ZnO), has been investigated in this work. The ZnO/Ag/ZnO multilayered films were deposited on glass substrates using dc magnetron sputtering method. The structure of the silver mid-layer was considered to play an important role in the enhanced optical transmission. The silver mid-layer was composed of randomly distributed silver particles (islands) which were connected by a thin continuous silver layer. When light impinged normal to the multilayered films, the layer-plus-islands silver could excite surface plasmons (SPs). The resonance between the incident light and the SPs could confine more light on the silver surface and enhanced the near field strength. The light could be reemitted on the exit side by decoupling the confined SPs, and the optical transmission could be enhanced. The surrounding ZnO layers also affected the optical transmission. The optical transmittances of multilayered films with 30 and 50 nm thick ZnO layers were higher those of multilayered films with 100 nm thick ZnO layers. The mechanism for enhanced optical transmission was discussed by considering the metal/dielectric interface model. The electrical properties were also studied in this work. The ZnO/Ag/ZnO multilayered films with high optical transmittance and low sheet resistance have the potential applications in solar cells and flat plate displays as transparent electrodes.