FRG: Tailoring the Properties of Dilute Nitride Semiconductor Alloys

技术：本项目探索铟成分（和晶格参数）与InGaAsN合金能带隙之间的关系。通过实验和理论结合的方法，旨在了解和控制稀氮半导体合金的原子到纳米级结构，从而为各种应用定制异质结构的性能。该项目是跨学科的，综合了材料科学、物理和电气工程的专业知识；密歇根大学和圣母大学的实验学家以及爱尔兰科克大学的理论学家将努力更深入地了解稀氮半导体异质结构的微观结构和特性。为此，将确定精确的合成条件，以控制这些合金的微观结构和由此产生的电子态和光发射效率。利用等离子体辅助分子束外延技术制备稀氮合金薄膜。该微结构将采用一种新颖的方法来定制，该方法使用生长前聚焦的铟和镓离子束注入来种子成分模式。原子到纳米尺度的结构将使用原位扫描隧道显微镜（STM），以及横断面扫描隧道显微镜和透射电子显微镜，高分辨率x射线衍射和核反应分析来表征。弹性性能将通过生长过程中晶圆曲率的实时测量和生长后的近场拉曼光谱来确定。电子状态将使用扫描隧道光谱、近场压电反射率、电阻率和霍尔测量，在常规和门控配置中进行检查。光学性质将使用吸收和光致发光、磁致发光和近场扫描光学显微镜来确定。所有这些结果将使用一组互补的计算研究来解释，包括密度泛函理论和紧结合计算来解释STM图像，并确定N聚类对弹性性能的影响；以及基于连续统和有效质量的计算N簇对电子迁移率和光学性质的影响。本项目所完成的工作将为开发新型电子、光电和光伏器件奠定基础。非技术：该项目涉及材料科学主题领域的基础研究问题，具有很高的潜在技术相关性。该研究将在基础水平上为电子器件的新理解和能力贡献基础材料科学知识。该计划的一个重要特点是通过培养学生在一个基础和技术上重要的领域的研究和教育的整合。这种方法是跨学科的，整合了材料科学、物理学和电气工程方面的专业知识，汇集了密歇根大学和圣母大学的实验学家和爱尔兰科克大学学院的理论家。这为研究生，本科生和高中生创造了独特的教育和培训机会，作为最前沿电子材料研究团队的一部分共同努力。该项目包括(a)为不同层次的学生（从K12到研究生）和几个代表性不足的群体（包括妇女、非洲裔美国人和拉丁美洲人）创造一个多学科的科学学习环境，以及(b)创造新知识，有望使新技术造福社会。

Technical: This project explores the relationship between indium composition (and lattice parameter) and the energy bandgap for InGaAsN alloys. The collaborative experimental and theoretical approach aims to understand and control the atomic to nanometer-scale structure of dilute nitride semiconductor alloys, in order to tailor the properties of heterostructures for a variety of applications. The project is interdisciplinary integrating expertise in materials science, physics, and electrical engineering; experimentalists at the U-Michigan and the U-Notre Dame and theorists at Ucollege in Cork, Ireland will strive for greater understanding of microstructure and properties of dilute nitride semiconductor heterostructures. To this end, the precise synthesis conditions needed to manipulate the microstructure and consequent electronic states and optical emission efficiencies of these alloys will be identified. Dilute nitride alloy films will be synthesized using plasma-assisted molecular-beam epitaxy. The microstructure will be tailored using a novel approach to seed compositional patterns using pregrowth In- and Ga- focused-ion-beam implantation. The atomic-to-nanometer-scale structure will be characterized using in-situ scanning tunneling microscopy (STM), as well as cross-sectional STM and transmission electron microscopy, high-resolution x-ray diffraction, and nuclear reaction analysis. Elastic properties will be determined with real-time measurements of wafer curvature during growth, and nearfield Raman spectroscopy following growth. The electronic states will be examined using scanning tunneling spectroscopy, near-field piezorelectivity, and resistivity and Hall measurements, in conventional and gated configurations. Optical properties will be determined using absorption and photoluminescence, magneto-luminescence, and near-field scanning optical microscopy. All of these results will be interpreted using a complementary set of computational studies, including density functional theory and tight-binding calculations to interpret STM images and determine the effects of N clustering on elastic properties; as well as continuum and effective-mass based calculations of the effects of N clusters on the electron mobility and optical properties. The work accomplished in this project will lay the foundation for a larger effort to develop novel electronic, optoelectronic, and photovoltaic devices.Non-Technical: The project addresses basic research issues in a topical area of materials science having high potential technological relevance. The research will contribute basic materials science knowledge at a fundamental level to new understanding and capabilities in electronic devices. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area. The approach is interdisciplinary integrating expertise in materials science, physics, and electrical engineering, bringing together experimentalists at the U-Michigan and the U-Notre Dame and theorists at U-College in Cork, Ireland. This creates unique education and training opportunities for graduate, undergraduate, and high school students working together as part of a team effort in forefront electronic materials research. The project includes (a) the creation of a multi-disciplinary scientific learning environment for students at a variety of levels (from K12 to graduate) and from several underrepresented groups (including women, African-Americans, and Latinos), and (b) the creation of new knowledge expected to enable new technologies that will benefit society.