高Al组分AlGaN中点缺陷的形成机理及调控研究

高Al组分AlGaN是制备深紫外光电子器件的理想材料，但高的缺陷密度（位错缺陷、点缺陷）严重影响了材料质量和器件性能。近年来，材料生长技术的发展使AlGaN中的位错缺陷显著降低，而点缺陷的影响日渐突出。本项目以高Al组分AlGaN中点缺陷形成机理及其调控为主要研究目标，采取理论与实验相结合，从点缺陷的形成能入手，基于密度泛函和半导体理论, 构建点缺陷形成能与载流子浓度的依存关系，获得点缺陷的电荷态、密度分布、形成能和能级位置；利用非破坏性的检测，实时表征点缺陷对AlGaN的光学和电学性能影响，获得点缺陷的存在方式、行为状态等信息，揭示高Al组分AlGaN中各类点缺陷的形成机理；在此基础上，通过载流子调控改变点缺陷的形成能从而实现对高Al组分AlGaN中点缺陷的调控，解决高Al组分AlGaN的掺杂问题，并建立点缺陷与器件光电性能的关联，为高性能AlGaN紫外光电子器件的研制奠定基础。

AlGaN with high Al composition is an ideal candidate for deep ultraviolet optoelectronic devices. However, the high density defects, including dislocation defects and point defects, affect the quality of the materials and the performance of devices seriously. In recent years, the development of AlGaN growth technology makes a significant reduction in dislocation defects, thus the point defect becoming a prominent problem. In this project, the formation mechanism and control method of point defects in AlGaN with high Al content will be studied using a method of combination the theory and experiment. Based on density functional theory, the dependence of the formation energy of point defects on the carrier concentration will be constructed and the charge state of point defects, the density distribution, formation energy and energy levels will be obtained. Besides, the non-destructive measurement will be used to obtain the optical and electrical properties of point defects in AlGaN real-time to study the evolution, status and other information of point defects, revealing the formation mechanism of all kinds of point defects in AlGaN with high Al content; On this basis, the points defects are controlled by carriers by changing the formation energy of points defects and thus solving the problem of doping in AlGaN with high Al content. Moreover, obtaining the association of point defects with the electrical and optical properties of AlGaN optoelectronic devices to accelerate the achievement of AlGaN deep ultraviolet devices with high-performance.