Site-Selective Optical and Magnetic Properties of Rare Earth Ion Doped Nitrides

技术：该项目旨在更好地了解掺Er宽禁带耐火氮化物材料(GaN；AlGaN)。该方法利用CEES(联合激发和发射光谱)和CL(阴极发光)技术，通过改变缺陷类型和浓度来研究和评估缺陷及其在激发过程中的详细作用。动力学过程将通过泵浦-探测反射率测量与时间分辨实验相结合来探索，在时间分辨实验中，一部分离子被共振激发，而其他离子通过注入电子或紫外线激光激发。此外，稀土离子将与共焦和近场光学光谱结合使用，作为本征局部场的探测器，利用它们的特征位移和斯塔克和塞曼效应的能级分裂。有两个问题特别令人感兴趣：(1)在最有效的紫外光发射体中的AlGaN中载流子局域化效应的性质，以及(2)在稀土掺杂的GaN中观察到的铁磁性的位置选择性性质，以及相变温度、磁化强度和其他磁性性质如何依赖于掺入位的相对数量。非技术性：该项目涉及具有高度技术相关性的电子/光子材料科学专题领域的基础研究问题。研究和教育活动将与研究生和本科生参与研究计划相结合。国际和平协会将继续通过利哈伊科学外联方案，积极为关于K-12高级材料的外联讲习班作出贡献。作为该项目的一部分，他将启动两项新的教育活动：(1)他将利用固体中稀土离子的原子性质来开发实验室实验，作为利哈伊大学现代物理课程的附加课程。在这方面，他将与利哈伊大学的物理学生协会(SPS)分会合作，创建几个“只是为了好玩”的实验，学生们可以在晚上的课时以外做这些实验；(2)为了增加少数族裔对科学的参与，国际和平基金会与两所历史悠久的黑人学院(格拉姆林，汉普顿)建立了合作关系；来自这两所学院的本科生将在夏季从事该项目，作为利哈伊大学物理学REU项目的一部分。

Technical: This project aims for greater understanding of Er-doped wide-bandgap refractory nitride materials (GaN; AlGaN). The approach utilizes CEES (combined excitation and emission spectroscopy) and CL (cathodoluminescence) techniques to study and assess defects and their detailed role in excitation processes through variation of defect types and concentrations. Dynamical processes will be explored by pump-probe reflectivity measurements in combination with time-resolved experiments, in which a subset of ions are excited resonantly while others are excited through injected electrons or by a UV laser. Additionally, rare earth ions will be used in connection with confocal and near-field optical spectroscopy as probes for intrinsic local fields utilizing their characteristic shifts and level splitting from Stark and Zeeman effects. Two issues are of particular interest: (1) the nature of carrier localization effects in AlGaN that are seen in the most efficient UV light emitters, and (2) the site-selective nature of ferromagnetism observed in rare earth doped GaN, and how the phase transition temperature, magnetization and other magnetic properties depend on the relative number of incorporation sites. Non-technical: The project addresses basic research issues in a topical area of electronic/photonic materials science with high technological relevance. Research and educational activities will be integrated with involvement of both graduate and undergraduates in the research program. The PI will continue to actively contribute to outreach workshops on advanced materials for K-12 through the Lehigh Science Outreach program. As part of this project the PI will initiate two new educational activities: (1) he will utilize the atom-like properties of rare earth ions in solids to develop laboratory experiments that serve as an add-on to the Modern Physics courses at Lehigh University. In this, he will collaborate with the Society of Physics Students (SPS) chapter at Lehigh University to create several 'just for fun' experiments that students can do outside the regular course schedules during evening hours; (2) in order to increase the involvement of minorities in science, the PI has established collaborations with two historically black colleges (Grambling, Hampton); undergraduates from these colleges will work on the project during the summer, as part of the Physics REU program at Lehigh University.