以表面等离子体为媒介的ZnO薄膜发光增强特性研究

采用两步法制备Si基Ag/ZnO双层结构薄膜,研究了Ag覆盖层的厚度和生长温度T对ZnO近带边发光强度的影响.对于厚度为100 nm的ZnO薄膜,发现Ag覆盖层的最佳厚度仅为8 nm,此时双层薄膜相对于单层ZnO薄膜的发光增强因子η达到最大值8.1;同时还发现,在最佳Ag层厚度下,生长温度T≥300 ℃时生长Ag所获Ag/ZnO双层薄膜的ZnO发光强度比生长温度T≤200 ℃时生长的双层薄膜样品大一倍以上,η ≈ 18.结合对双层薄膜表 关键词： 表面等离子体共振 复合薄膜

Surface-plasmon-mediated emission enhancement from Ag-capped ZnO thin films

Ag/ZnO bilayer thin films are fabricated on Si substrates via two-step approach of "ZnO sputtering + Ag evaporation". The enhancement of the near band edge (NBE) emission of the ZnO film is realized through coupling between the surface plasmon resonating energy at Ag/ZnO interface and the photonic energy of ZnO NBE emission. The dependence of the emission enhancement ratio η of ZnO on the thickness and the growth temperature T of Ag cap-layers are investigated. By evaporating Ag(8 nm) cap-layer onto ZnO(100 nm) film at high substrate temperatures (T≥300 ℃), the η value reaches about 18,i.e., η≈18, which is more than twice that of Ag(8 nm)/ZnO(100 nm) bilayer films grown at low temperatures (T≤200 ℃). It is found that the realization of the larger η can be ascribed to the bigger surface roughness of Ag/ZnO bilayer samples prepared under higher growth temperatures.