Understanding p-Type Doping in GaN: the Role of Mg

技术：本项目旨在了解用于生产p型GaN的镁杂质的化学、结构和光学灵敏度，以便了解目前实现高掺杂密度的限制，并可能实现新的掺杂方法。它利用电子顺磁共振(EPR)谱来探测GaN中镁杂质的光学灵敏度和化学反应活性。具体地说，监测以当前器件中使用的典型镁浓度生长的薄膜和通过旨在实现高空穴密度的方法生长的薄膜之间的热退火行为的变化。此外，这项研究还涉及到一种探测镁杂质的新方法：依赖时间的光电子顺磁共振。对这些数据的分析可以提供有关镁和其他缺陷之间的电荷交换的信息，这可能会随着镁浓度的增加而改变。其他实验包括国家强磁场实验室提供的高频EPR。高频实验可以揭示杂质的局域对称性和应变的作用。总体而言，该项目旨在调查限制有效p型掺杂的因素，并可能为最大化GaN的空穴密度和导电性提供方向。非技术性：该项目解决具有高度技术相关性的材料科学主题领域的基础研究问题。该研究项目的成功可能有助于开发更好的发光二极管和电子设备。这位PI曾指导过许多科学、数学和工程专业的本科生，他在阿拉巴马大学教授大二水平的科学和技术荣誉研讨会，其中包括一个关于未来照明技术和高效高功率/高频电子设备的部分。优等生与博士生在PI实验室的合作将培养一种对成功至关重要的跨学科研究意识，这是他们正规教育的补充。

Technical: This project aims to understand the chemistry, structure, and optical sensitivity of the Mg impurity used to produce p-type GaN so that the present limitations to achieve a high dopant density can be understood and new approaches to doping may be realized. It employs electron paramagnetic resonance (EPR) spectroscopy to probe the optical sensitivity and chemical reactivity of the Mg impurity in GaN. Specifically, changes in the thermal annealing behavior between films grown with the typical Mg concentration used in the present day devices and those grown by methods intended to achieve high hole densities are monitored. Further, the research involves a new method to probe the Mg impurity: time-dependent photo-EPR. Analysis of such data could provide information about charge exchange between Mg and other defects, which will likely change as Mg concentration is increased. Additional experiments include high frequency EPR available at the National High Magnetic Field Laboratory. The high frequency experiments may reveal the local symmetry of the impurity and the role of strain. Overall, the project is designed to investigate factors that limit effective p-type doping and may provide direction to maximize hole density and conductivity of GaN.Non-technical: The project addresses basic research issues in a topical area of materials science with high technological relevance. A success of the research project could contribute to development of better light emitting diodes and electronic devices. The PI, who has mentored many undergraduates in science, mathematics and engineering, teaches a sophomore-level Science and Technology Honors seminar at the University of Alabama, which includes a section on future lighting technologies and efficient high power/high frequency electronic devices. The collaboration of the Honors students with PhD candidates in the PI's laboratory will foster a sense of interdisciplinary research essential for success complement to their formal education.