Point Defects in Gallium Nitride: Experiment and Theory

非技术描述：氮化镓(GaN)是发光二极管(LED)等光电子学中的关键元件。GaN中点缺陷的研究和识别是非常重要的，对长寿命LED具有直接的技术意义。这项拟议研究的目标是将GaN中缺陷的物理学带到一个新的理解水平，揭示缺陷的微观本质，并解决半导体物理领域中长期存在的问题。该研究通过将先进的实验技术与高性能计算相结合，将实验与理论相结合。与半导体行业的合作预计将对实际应用产生直接影响。该项目还为弗吉尼亚联邦大学一个相对较小的物理系的研究和教育奠定了坚实的基础。来自代表性不足群体的学生有机会获得最先进的实验和计算的实践经验。技术描述：本研究的目标是深入和全面地了解GaN中的点缺陷。本研究调查了大量的点缺陷和各种缺陷复合体。这项实验工作使用先进的工具，如单轴应力下的光致发光，与使用混合泛函理论的第一原理计算并行进行。将单轴压力引起的晶格变形引入理论，可以直接比较理论预测的缺陷相关光学性质的变化与实验结果。基于发光光谱及其偏振特性的外应力效应分析可以揭示点缺陷的对称性和电子结构。综合实验/理论方法允许直接识别缺陷并确定其微观结构。

Non-technical Description: Gallium nitride (GaN) is a key component in optoelectronics, such as light-emitting diodes (LED). The investigation and identification of point defects in GaN is very important and has immediate technology relevance to longer life time LEDs. The goal of the proposed research is to bring the physics of defects in GaN to a new level of understanding, to uncover the microscopic nature of defects, and to solve longstanding problems in the field of semiconductor physics. The research integrates experiment and theory by combining advanced experimental techniques with high performance computing. Collaboration with the semiconductor industry is expected to have a direct impact on practical applications. The project also builds a strong foundation for research and education in a relatively small Physics Department at Virginia Commonwealth University. Students from underrepresented groups have the opportunity to gain hands-on experience with state-of-the-art experiment and calculations.Technical Description: The goal of this research is to gain an in-depth and comprehensive understanding of point defects in GaN. The study investigates a large number of point defects and various defect complexes. The experimental work, using advanced tools such as photoluminescence under uniaxial stress, is conducted in parallel with first-principles calculations using the hybrid functional theory. Incorporation of lattice deformations due to uniaxial pressure into the theory enables direct comparison between the theory-predicted changes in defect-related optical properties and experimental results. The symmetry and electronic structure of point defects can be revealed from the analysis of the effect of external stress based on the luminescence spectrum and its polarization. The integrated experiment/theory approach allows the direct identification of defects and the determination of their microscopic structure.