ABSTRACT The photoluminescence spectra excited by different wavelength light from ZnO samples with and without SiOx passivation demonstrated that the excitation behavior of structured green luminescence (GL-S) band is determined by the surface conditions or the morphological forms. The lowest energy of photons able to excite the GL-S band varied from 3.380 eV down to a value far below the zero phonon line of GL-S band, depending on the defect density in the region near to the sample surface. The imperfections like cracks, scratches, and voids etc. were found decisive for the effectiveness of SiOx passivation on the GL-S band, which is removable only for the samples with good surface conditions. In addition, the phonon energy in GL-S band was determined to be ∼3 meV lower than that of longitudinal optical phonons and thus was associated with the surface optical mode. The evidence of a link between the GL-S band and the optical emissions on sample surface revealed that there is no necessity to connect the GL-S band with any specific defects in the inside of samples. This optical emission mechanism is not only helpful to settle the relevant issues of visible luminescence in the research of ZnO, but also important to the study of other phenomena related to photoexcitation.

中文翻译：

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ZnO 中结构化绿色发光带的样品相关激发行为

摘要 ZnO 钝化和未钝化的 ZnO 样品的不同波长光激发的光致发光光谱表明，结构化绿色发光 (GL-S) 带的激发行为是由表面条件或形态决定的。能够激发 GL-S 带的光子的最低能量从 3.380 eV 下降到远低于 GL-S 带零声子线的值，这取决于样品表面附近区域的缺陷密度。发现裂纹、划痕和空隙等缺陷对 GL-S 带上 SiOx 钝化的有效性具有决定性意义，GL-S 带仅可去除具有良好表面条件的样品。此外，GL-S 带中的声子能量被确定为比纵向光学声子低约 3 meV，因此与表面光学模式相关。GL-S 波段与样品表面的光发射之间存在联系的证据表明，没有必要将 GL-S 波段与样品内部的任何特定缺陷联系起来。这种光发射机制不仅有助于解决ZnO研究中可见光发光的相关问题，而且对其他光激发相关现象的研究也具有重要意义。