氧化锌微米花的共振拉曼和“负热淬灭”效应

Resonant Raman scattering and “negative thermal quenching” of ZnO microflowers

利用化学气相沉积(CVD)的方法通过热氧化高纯锌粉在硅衬底上得到氧化锌微米花.X射线衍射(XRD)结果表明,其具有六角纤锌矿晶体结构.场发射扫描电子显微镜(FE-SEM)图像表明,合成的样品是由很多长且直的ZnO亚微米棒组成的微米花,具有六角棱柱端面,棒的长度在30μm到50μm之间.在背向共振拉曼散射光谱测量中,观测到ZnO A1(LO)的五阶声子紫外共振拉曼散射,表明样品具有较高的晶体质量.在变温光致发光谱测量中,观察到明显的中性受主束缚激子(A0X)的“负热淬灭”效应,并讨论了其产生原因.

In this paper, ZnO microflowers were synthesized on silicon substrates by the thermal oxidation of pure Zn powder （99.99%）. The X-ray diffraction spectrum （XRD） showed that ZnO microflowers have a hexagonal wurtzite structure. The field-emission scanning electron microscope （FE-SEM） image indicated that as-synthesized ZnO microflowers consisted of lots of long and straight microrods, which possessed hexagonal prism morphology. The length of microrods ranges from 30 to 50μm. The resonant Raman spectrum showed muhiphonon scattering process the 5th-order longitudinal optical phonon （A1 （LO）） mode in the backscattering geometry, indicating that the sample is of high quality. In the temperature-dependent photoluminescence （PL） spectra, ＂negative thermal quenching＂ phenomenon of neutral acceptor bound exciton （A^0X） was observed, and its origin was discussed.