GOALI: Charge Transfer in Semi-Insulating GaN

GOALI：半绝缘 GaN 中的电荷转移

• 批准号: 1308446
• 负责人: Mary Ellen Zvanut
• 金额: $ 36.8万
• 依托单位: University of Alabama at Birmingham
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1308446&HistoricalAwards=false
• 关键词: GOALI; Charge; Transfer; Semi; Insulating

Technical Description: Although GaN is effectively used in lighting applications, some electronic devices require high resistivity material. The goal of this GOALI project is to investigate and understand charge transfer mechanisms among the defects used to achieve insulating GaN and to assess the influence of the intentional impurities on crystal quality. Specifically, electron paramagnetic resonance (EPR) spectroscopy is used to probe charge transfer between the intentionally added Fe impurities and intrinsic donors. The EPR measurements provide a fingerprint of the Fe and donor defects, and, combined with photo-excitation, are used to monitor various charge exchange processes. Additionally, several different charge states of the Fe impurity as well as other potential defect centers are probed with optical absorption spectroscopy, and overall crystal quality is assessed with x-ray diffraction. The experiments primarily address bulk Fe-doped substrates grown by hydride vapor phase epitaxy at Kyma Technologies, the industrial collaborator of this project. However, additional studies include comparisons with samples grown by other growth techniques, such as high pressure solution, and doped with different compensating impurities so that optimal growth parameters for stable insulating nitride substrates may be determined.Non-technical Description: The insights gained by directly probing defects in GaN provide input for improved growth techniques, so that high-quality, high-resistivity material needed for future power electronics can be realized. By interacting with the industrial collaborators, students gain a view of science not available in a classroom setting. Furthermore, a summer research experience with Kyma is being offered to one of the graduate students working on this research, and at least one seminar by a Kyma scientist is planned. Both are intended to introduce students to the practical issues associated with material growth and device development. At the pre-college level, the PI gives an afternoon presentation on colloquial topics related to GaN devices at the week-long high-school Physics Bridge workshop organized by a colleague in the department.

技术描述：虽然GaN有效地用于照明应用，但某些电子器件需要高电阻率材料。 GOALI项目的目标是研究和理解用于实现绝缘GaN的缺陷之间的电荷转移机制，并评估有意杂质对晶体质量的影响。具体而言，电子顺磁共振（EPR）光谱用于探测有意添加的Fe杂质和本征施主之间的电荷转移。EPR测量提供了Fe和施主缺陷的指纹，并且与光激发相结合，用于监测各种电荷交换过程。此外，还使用光学吸收光谱法探测Fe杂质的几种不同电荷状态以及其他潜在缺陷中心，并使用X射线衍射评估总体晶体质量。该实验主要解决在Kyma技术，该项目的工业合作者的氢化物气相外延生长体铁掺杂衬底。然而，额外的研究包括与通过其他生长技术生长的样品进行比较，例如高压溶液，并掺杂不同的补偿杂质，以便可以确定稳定绝缘氮化物衬底的最佳生长参数。通过直接探测GaN中的缺陷获得的见解为改进的生长技术提供了输入，可以实现未来电力电子所需的高电阻率材料。通过与工业合作者的互动，学生获得了在课堂环境中无法获得的科学观。此外，正在为从事这项研究的一名研究生提供Kyma的夏季研究经验，并计划至少举办一次Kyma科学家的研讨会。两者都旨在向学生介绍与材料生长和器件开发相关的实际问题。在大学预科阶段，PI在由部门同事组织的为期一周的高中物理桥研讨会上就与GaN器件相关的口语主题进行了下午的演讲。