Influence of Annealing on the Structure and 1.54 mu m Photoluminescence of Er-Doped ZnO Thin Films Prepared by Sol-Gel Method

We have investigated the effects of Er concentration, post-annealing time and temperature through a sol-gel preparation method on the structure and 1.54-mu m-related photoluminescence (PL) of ZnO:Er thin films. The results illustrated that the 1.54 mu m emission was greatly influenced by the local structure of Er-O complex and ZnO host. The active oxygen movement during annealing process resulted in the formation of optical active center of Er ions, which probably attributed to the formation of a similar pseudo-octahedron with C-4v structure around Er. The preferential orientation of ZnO host had more effect on the 1.54 mu m PL intensity than the crystallinity of ZnO host. Therefore, the optimum annealing condition was about 800 degrees C/2 h and the appropriate concentration was about 0.05 at % Er. A low-cost and fast formation of highly efficient Er centers in ZnO host for strong luminescence at near-infared region should be benefit for both fundamental research and also applications of light-emitting devices. (C) 2011 The Japan Society of Applied Physic