GOALI:A Study of Point Defects in Thick, Free-Standing Acceptor-Doped GaN

非技术描述：半导体是一类材料，它使大多数现代电子产品的发展成为可能，包括平板电脑、手机和医疗诊断设备。该项目研究的半导体氮化镓是2014年诺贝尔物理学奖的焦点，因为其特殊的材料特性使许多房主现在熟悉的节能LED照明成为可能。令人惊讶的是，材料和结构缺陷是这种半导体成功应用的必要部分。出于这个原因，本研究项目调查了一类充当电子陷阱的缺陷的性质。基本信息和实用信息都是从电子和结构研究中确定的。除了为从事这一重大技术问题的学生提供的基本教育好处外，学生还可以从积极种植材料和器件的工业人员那里获得第一手知识并了解潜在的进展。技术描述：该项目旨在通过微观研究受主杂质的结构和电荷状态来更好地了解GaN中的受主杂质。具体的焦点是用电子顺磁共振(EPR)测量掺有技术上重要的受主元素如镁和碳的GaN自支撑晶体的厚度。直到最近，GaN的EPR一直受到缺陷总数有限和薄膜固有的不均匀应变的阻碍。厚的独立GaN晶体的可用性增加了可检测中心的数量并最大限度地减少了应变，从而使研究EPR独特的特性成为可能，如电荷态和局域结构。此外，在Goali合作伙伴Kyma Tech的帮助下，研究了缺陷对器件性能的潜在影响。这项研究提供了以前无法获得的基本性质，如缺陷对称性，以及实际信息的确定，如特定缺陷与能级的关联。总体而言，这些结果增强了对点缺陷在体相和薄膜受主掺杂GaN中的作用的理解。

Nontechnical description: Semiconductors are a class of materials that has enabled the development of most modern electronics including tablets, cell phones, and medical diagnostic equipment. Gallium nitride, the semiconductor studied in this project, was the focus of the 2014 Nobel Prize in Physics because its special material properties made possible the energy efficient LED lighting now familiar to many homeowners. Surprisingly, material and structural imperfections are a necessary part of the successful application of this semiconductor. For this reason, the present research project investigates the properties of a certain class of imperfections that act as traps for electrons. Both fundamental and practical information are determined from the electronic and structural studies. In addition to the basic educational benefits afforded students working on this technologically significant issue, students gain first-hand knowledge and learn about potential advances from industrial personnel who actively grow the materials and devices.Technical description: The project is designed to better understand the acceptor impurities in GaN by microscopically investigating their structure and charge state. The specific focus is electron paramagnetic resonance (EPR) measurements of mm-thick free-standing crystals of GaN doped with technologically important acceptors such as magnesium and carbon. Until recently, EPR of GaN has been hampered by the limited total number of defects and non-uniform strain inherent to thin films. The availability of thick free-standing GaN crystals increases the number of detectable centers and minimizes strain, thus enabling the study of characteristics uniquely addressed by EPR, such as charge state and local structure. In addition, the potential influence of the defects on device properties is investigated with the help of a GOALI partner, Kyma Tech. The study provides previously unavailable fundamental properties such as defect symmetry, and the determination of practical information such as association of a specific defect with an energy level. Overall, the results enhance the understanding of the role of point defects in both bulk and thin film acceptor-doped GaN.