Microstructure And Optical Property Of Dy-doped ZnO Nanopowders

Zinc oxide (ZnO) is an important II-VI wide band gap (Eg=3.37 eV) semiconductor material with wutzite structure. Due to the large exciton binding energy of 60 meV, which ensures the high efficient excitonic emission at room temperature, it is regarded as one of the most promising material for UV light-emitting diodes (LED), laser diodes (LD), gas sensors, flat panel displays, etc. In order to improve the UV emisson efficiency, it is very important to pay much attention on the visible emission mechanisms of ZnO。In this paper, the microstructure and optical property of ZnO:Dy were investigated by X ray diffraction, scan electron morphology and photoluminescence spectra.ZnO:Dy nanoparticles were synthesized by hydrothermal method。A strong UV emission peak and a wide visible emission band from 550-650 nm were observed. They were attributed to ZnO near-band-edge emission and deep level defects, respectively. .As increasing Dy concentration, the morphology of ZnO was changed from nanoparticles to nanoneedles and enhanced UV emission could be observed. The energy transfer between ZnO and Dy did not occurred. These results indicated that Dy ion was possible locating on the surface of the ZnO nanoparticle but not in ZnO.