Ga掺杂对ZnO纳米结构可见光发射的抑制效应

Suppression of visible light emission of ZnO nanostructures by Ga-doping

采用碳热还原反应和原位掺杂的方法制备了不同Ga掺杂浓度的ZnO纳米结构.X射线衍射显示掺杂纳米结构中为单一的氧化锌纤锌矿结构.扫描电子显微镜观测发现随掺杂浓度的增大,纳米结构的形貌逐渐从纳米六棱柱变为纳米锥.光致发光和X射线光电子能谱测量分别发现随着掺杂浓度升高,纳米结构的可见发光强度和其中空位氧峰相对强度逐渐减小直至消失,两者存在很强的相关性.上述结果为ZnO可见光发射的氧空位机理提供了新的实验证据.对Ga掺杂抑制纳米结构中氧空位的原因进行了分析.

Ga-doped ZnO nanostructures with various doping concentrations are prepared by using carbon thermal reduction reaction and in situ doping method. X-ray diffraction measurement reveals only wurzite structures existing in Ga-doped ZnO nanostructures. Scaning electron microscopy observations show that with the increase of Ga doping concentration, the morphology of ZnO nanstrucuture varies gradually from nanorods to nanocones. From the photoluminescence, we find that the visible light emission of ZnO nanostructures can be suppressed obviously and even disappears with the increase of Ga doping concentration. Moreover, the suppression of visible light emission is correlated well with the behavior, and X-ray photoelectron spectroscopy measurement reveals that the vacancy oxygen in ZnO nanostructure decreases drastically with the increase of Ga doping concentration. This result offers a new strong evidence for the mechanism that the visible light emission ofZnO nanostructures is caused by the oxygen vacancy defects. This work also demonstrates that a little Ga incorporation into ZnO nanostructures can effectively reduce the oxygen vacancy defects occurring.