| Summary: | 碩士 === 國立交通大學 === 材料科學與工程系 === 91 === Novel hierarchical polygon prismatic nano-structures of wurtzite Zn-ZnO have been successfully grown on silicon by thermal vapor transport and condensation method. Generally, the crystalline phase and control of the seeds at the nucleating stage are critical for directing the intrinsic shapes of nanocrystals at the initial time. Thus, in this work, the organic solvent with zinc chemical compound was first coated and used as seeds on the patterned substrate. Subsequently, it was grown by thermal vapor transport with ZnO powder at 250°C (substrate) in Ar atmosphere. The samples were characterized using X-ray diffraction, scanning and transmission electron microscopy, and photoluminescence spectroscopy. The as-synthesized Zn-ZnO polygon prismatic nano-structure consisted of hexagonal metallic nuclei (Zn) covered with an oxidation outer thin film (ZnO). Depending on different working temperature and reaction atmosphere, Zn- ZnO polygon prismatic structure having various morphologies can be developed. In order to recognize the growth mechanism of Zn-ZnO polygon prismatic structure and temperature effect, different heat-treatment were designed to observe the morphology and crystallization of Zn-ZnO polygon prismatic structure. The possible formation mechanism for the Zn-ZnO polygon prismatic crystal structure is identified and proposed as the Zn-ZnO mineral bridge mechanism. The non-perfect Zn-ZnO polygon prismatic structure shows weakly UV emission and strongly deep-level emission. However, the PL properties and crystallization of Zn-ZnO polygon prismatic nanocrystals could be improved by suitable post-treatment.
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