【作者】 冯夏；

【导师】 康俊勇；

【作者基本信息】 厦门大学 ， 凝聚态物理， 2006， 博士

【摘要】 新型半导体异质结构是当前半导体科学技术研究的前沿领域。借助异质材料的接触与融合所产生的表面和界面的奇异功能特性,来创造新型材料和器件,已成为许多研究领域的指导思想。本论文从ZnO基半导体出发,探索发展新结构、揭示新现象、阐释其物理机制,着重介绍了两方面工作:ZnO/Au异质结构材料设计、制备,并对ZnO薄膜的应力、发光特性以及极性控制作进一步的探讨;Zn₂SiO₄纳米线和Zn₂SiO₄-Zn异质结构纳米同轴线的制备,及其发光性质研究。在ZnO/Au异质结构材料的研究中,首先采用了基于密度泛函理论的从头计算方法,参照层晶模型的构建方法,设计了Au（111）及其上面的ZnO形成的ZnO/Au异质结构模型。通过模拟计算ZnO不同结构的体系总能,优化并确定了ZnO薄膜的结构性质。接着我们在Si衬底上溅射沉积了两种厚度的Au薄膜,后用气相沉积方法在不同温度下沉积了ZnO薄膜。研究发现Au形成纳米晶粒后生长的ZnO薄膜表面呈六角对称小丘状,薄膜沿c轴生长,晶粒尺寸较大,晶粒间接合较好,晶体质量较好;通过Raman、CL、CBED等表征手段表明,用纳米Au晶粒引导异质生长ZnO薄膜,不仅能够充当生长晶核,还能够控制ZnO薄膜为Zn极性、降低Si衬底与外延层间的失配应力、提高带边紫外发光效率。此外结合理论模型,进一步探讨Au纳米颗粒上ZnO薄膜的生长机制;提出在晶核形成时处于富Zn状态,随着晶核慢慢向边上生长,Zn和O的比例越来越接近理想化学剂量配比,ZnO的质量也更好,岛状的ZnO慢慢接合在一起,形成质量较好的无晶界的薄膜结构。另一方面,我们用简单的气相沉积生长了Zn₂SiO₄纳米线和Zn₂SiO₄-Zn异质结构纳米同轴线阵列。使用了包括扫描电子显微镜、能量色散X射线谱、高分辨透射电子显微镜以及X射线衍射等各种实验方法对样品进行了表征,提出了一种新的应力促进生长机制,为生长均匀的纳米同轴线提供一种新的技术。同时测量了不同温度下样品的阴极荧光谱,在300 nm左右、560 nm和865 nm左右分别出现了强度依次减弱的峰。各峰的半高宽都随温度增长而增大。通过对比Zn₂SiO₄纳米线的发光特性表明,回音壁模式为光在Zn₂SiO₄纳米线内传播的主要模式,因而不同直径的Zn₂SiO₄纳米线得到不同波长的发光;波长约为560 nm更多还原

【Abstract】 One of the promising avenues in the current semiconductor science and technology research is the development of the novel semiconductor heterogeneous functional materials. It is extremely important to explore materials and devices with new properties and functions. This thesis aims to grope for new structure, open out new phenomena and provide a thorough insight into their physical mechanisms. Two aspects have been emphasized; one is the material design and preparation of ZnO/Au/Si heterogeneous epitaxial film, and besides, having further considerations of the stress, optical properties and the polarity control; the other one is the preparation of the Zn₂SiO₄ nanowires, the Zn₂SiO₄-Zn nanocable heterostructures and the investigation of their fascinating optical properties.First-principles computation based on the density functional theory were performed to investigate the initial growth of ZnO films on Au layer, the results of which provided an intrinsic geometric structure of the formation of the Zn-polar ZnO film. And then, the properties of ZnO grown under different conditions were characterized. The results proved that the Au nanocrystallites can play as the role of crystal nucleus, and that ZnO on Au layer displayed a film structure that had no grain boundary and showed a surface composed of hexagonal hillocks. Furthermore, X-ray diffraction, Raman, and cathodoluminescence data supported that the hexagonal hillock grains were well aligned in the c axis. We believed that Zn was rich on the top of the hillocks where the nuclei initiated. Zn and O reach the stoichiometric ratio when the nuclei grew gradually to the side. The islands of ZnO joined together, and then formed a ZnO film of good quality without grain boundary. With Au as the buffer layer, the misfit stress is minimized, the UV emission is improved, and Zn-polarity is controlled. All of these might affect the electrical conductivity of ZnO.Chemical vapor deposition was used to grow Zn₂SiO₄ nanowires and Zn₂SiO₄-Zn nanocable arrays. Morphological, chemical and crystallographic characterizations of the as-grown samples were carried out by SEM, EDS, TEM and更多还原