標題: | Efficient UV photoluminescence from monodispersed secondary ZnO colloidal spheres synthesized by sol-gel method |
作者: | Cheng, HM Hsu, HC Chen, SL Wu, WT Kao, CC Lin, LJ Hsieh, WF 光電工程學系 Department of Photonics |
關鍵字: | photoluminescence;sol-gel;nanomaterials;ZnO |
公開日期: | 15-四月-2005 |
摘要: | ZnO colloidal spheres were synthesized by sol-gel method with a narrow size distribution. We controlled the size of the spheres during the secondary reaction with various amounts of primary reaction supernatant. The optimized condition of ZnO powders with an average diameter of 185 nm was obtained for structure analysis and study of optical properties. Transmission electron microscopy and X-ray diffraction reveal that the spheres are polycrystalline in the pure wurtzite phase. Markedly enhanced near-band-edge ultraviolet pbotoluminescence and significantly reduced defect-related visible emission were also observed. We attribute this observation to the localized bound excitons with high density of defect states. In addition, broad yellow emission and green emission were observed when the powders were post-annealed at 500 degrees C in air ambience. The origins of the defect-induced visible emissions are attributed to oxygen interstitials and oxygen vacancies. (c) 2005 Elsevier B.V. All rights reserved. |
URI: | http://dx.doi.org/10.1016/j.jcrysgro.2004.12.133 http://hdl.handle.net/11536/13815 |
ISSN: | 0022-0248 |
DOI: | 10.1016/j.jcrysgro.2004.12.133 |
期刊: | JOURNAL OF CRYSTAL GROWTH |
Volume: | 277 |
Issue: | 1-4 |
起始頁: | 192 |
結束頁: | 199 |
顯示於類別: | 期刊論文 |