GaN/ZnO外延膜中位错形成机制的透射电子显微分析研究

项目名称： GaN/ZnO外延膜中位错形成机制的透射电子显微分析研究

项目编号： No.11304354

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 数理科学和化学

项目作者： 吴东昌

作者单位： 中国科学院苏州纳米技术与纳米仿生研究所

项目金额： 30万元

中文摘要： ZnO是生长高质量低位错密度GaN的理想衬底。这是因为它们之间的晶格失配仅为约1.8%。我们使用氢化物气相外延（HVPE）在ZnO衬底上成功制得了GaN外延膜。但为了进一步降低其位错密度，还需要了解其位错形成机制，解决一些基本科学问题，例如此时引起位错的主要原因是否还是晶格失配？是否还有其它重要原因？为此，本项目将通过透射电子显微分析，研究用HVPE法在ZnO单晶衬底、ZnO薄膜及柱状ZnO阵列上生长的GaN外延膜的位错及其形成机制。通过对比研究，分析晶格失配、ZnO晶体质量、界面元素扩散等因素对GaN位错形成过程的影响；利用各种可定量化的参数，通过模拟、计算、统计和分析，对各种影响因素进行定量化描述，并从应力分布的角度进行分析，从而找到引起位错的主要原因，分别探讨在此条件下的位错形成机制。本研究将为生长更低位错密度的GaN奠定必要的实验与理论基础。

中文关键词： 氮化镓；位错；ZnO衬底；电子显微术；

英文摘要： ZnO is an ideal substrate for growing high-quality GaN,because they have a low lattice mismatch,~1.8%. Some reports confirm that it could reduce the dislocation density in GaN effectively. We have successed to grow high quality GaN on ZnO substrates by Hydride Vapor Phase Epitaxy (HVPE).However, the formation mechanism of dislocations is still unclear, and some fundamental issues remain to be resolved, such as whether the lattice mismatch is still the main reason to cause dislocations, and if there are other important reasons need to be considered? The answers will be helpful to further reduce the dislocation density in GaN. In this project, TEM analysis will be employed to research the formation of dislocations in GaN grown on three different kinds of ZnO substrates by HVPE. The substrates used are single-crystal ZnO substrate, ZnO thin films and columnar ZnO array grown on sapphire. The role of the lattice mismatch,crystal quality of ZnO and element diffusion at interface to the formation of dislocations in GaN will be studied.Some quantitive parameters and strain map will be employed to help finding the main reason which cause dislocations in GaN.This study is essential for growing GaN with a lower dislocation density.

英文关键词： GaN；Dislocation；ZnO substrate；Electron microscopy；