CAREER: Theory of Epitaxial-Oxide-Semiconductor Nanosystems

技术摘要：该职业奖支持旨在为外延氧化物半导体纳米系统开发理论框架的计算和理论研究，以及面向本科生和高中生的计算材料研究教育。半导体上的晶体外延氧化物(COS)为利用硅以外的材料(如Ge或GaAs)的互补金属氧化物半导体(CMOS)技术开辟了一条新的途径。COS的其他应用位于硅技术路线图的末尾；晶体氧化物的主要优势是它在硅衬底上的外延注册，通过消除界面缺陷来实现卓越的器件性能。CoS与最近发现的氧化物外延半导体(SOX)相结合，提供了另一组令人兴奋的可能性来探索。PI旨在为新兴的纳米级外延氧化物半导体系统领域开发一个全面的理论框架。主要研究了两个方面的基本问题：1.氧化物-半导体和半导体-氧化物体系的晶体生长。氧化物半导体异质外延成功的关键是实现二维或Frank-Van der Merwe生长。除了晶格和热失配之外，还必须考虑跨界面的根本不同类型的键合之间的转变。PI将研究金属间化合物锌作为离子氧化物和共价半导体之间的过渡层的使用。中心思想是利用锌化合物中的本征电荷转移，迫使电负性较强的金属承担半共价键，并继续进入半导体。另外两个关键问题是由于界面对称性的破坏(例如闪锌矿到钙钛矿)造成的90个孪晶，以及两种材料之间的阶跃不可公度。将纳米组装的原子几何和电子结构与其电学性质(如电荷转移和保留)联系起来，将使PI能够评估这些系统的可能应用。这种方法是基于PI最近开发的从头算总能量方法和原子尺度的电子传输技术。这项工作将需要与学术界和产业界的实验人员密切合作。为了将实用理论纳米科学的兴奋带入本科教育，PI计划开发、改进和加强一门名为“纳米技术计算材料实践”的新课程。本课程将面向物理、化学、电气工程和化学工程专业的大四学生。还将与LBJ科学学院的物理教师合作，开发一个旨在吸引女高中生学习纳米科学的外联计划。LBJ科学学院是一所磁石高中，有大量少数族裔学生。PI的目标是为女学生创造一个机会，让他们在PI的研究小组中度过暑假，学习计算纳米科学。这项活动将与德克萨斯大学一个成功的现有UTeach项目相协调。非-技术总结：该职业奖项支持旨在发展对半导体表面纳米系统和结构的理论理解的计算和理论研究，以及以本科生为重点的计算材料研究教育。PI将使用先进的计算工具，从组成原子开始研究如何在半导体表面生长氧化物材料，重点是硅以外的材料，目前电子行业的主力。PI还将研究所产生的纳米系统的电子性质。国际和平研究所将专注于基础材料科学和表面科学问题。这项工作有助于为与当前的电子设备技术相比具有显著更高的性能和增强的功能的半导体电子设备奠定理论基础。PI还将探索这些不寻常系统中可能出现的新现象。为了将实用理论纳米科学的兴奋带入本科教育，PI计划开发、改进和加强一门名为“纳米技术计算材料实践”的新课程。本课程将面向物理、化学、电气工程和化学工程专业的大四学生。还将与LBJ科学学院的物理教师合作，开发一个旨在吸引女高中生学习纳米科学的外联计划。LBJ科学学院是一所磁石高中，有大量少数族裔学生。PI的目标是为女学生创造一个机会，让他们在PI的研究小组中度过暑假，学习计算纳米科学。这项活动将与德克萨斯大学现有的成功的UTeach项目相协调。

TECHNICAL SUMMARY:This CAREER award supports computational and theoretical research that aims to develop a theoretical framework for epitaxial-oxide-semiconductor nanosystems and education in computational materials research targeted on undergraduate and high-school students.Crystalline epitaxial oxides on semiconductors (COS) open a new avenue for complementary metal oxide semiconductor (CMOS) technology utilizing materials other than Si, e.g. Ge or GaAs. Other applications of COS are at the end of the Si technology roadmap; the main advantage of a crystalline oxide is its epitaxial registry to the Si substrate that results in superior device performance by eliminating interfacial defects. COS combined with recently discovered epitaxial semiconductors on oxides (SOX) provides another set of exciting possibilities to explore. The PI aims to develop a comprehensive theoretical framework for the emerging field of nanoscale epitaxial oxide semiconductor systems. The research focuses on fundamental problems in two areas:1. Crystal growth of oxide-semiconductor and semiconductor-oxide systems.2. "Tunability" of the electronic and transport properties of epitaxial oxide-semiconductor nanosystems.The key to successful oxide-semiconductor heteroepitaxy is to achieve two-dimensional or Frank-Van der Merwe growth. In addition to lattice and thermal mismatch, the transition between fundamentally different types of bonding across the interface must be considered. The PI will investigate the use of intermetallic Zintl compounds as transition layers between ionic oxides and covalent semiconductors. The central idea is to exploit the intrinsic charge transfer in a Zintl compound to force the more electronegative metal to assume semi-covalent bonding which continues into the semiconductor. Two other key problems are the 90 twin domains caused by breaking of the symmetry across the interfaces (e.g. zinc-blende to perovskite), and step incommensurability between two materials. Relating the atomic geometry and electronic structure of the nanoassembly to its electrical properties, such as charge transfer and retention, will enable the PI to assess possible applications of these systems. The approach is based on ab-initio total energy methods and atomic-scale electron transport techniques that the PI has recently developed. The work will entail close collaboration with experimentalists in academia and industry.To bring the excitement of practical theoretical nanoscience into undergraduate education, the PI plans to develop, improve, and enhance a new course entitled "Practicum on Computational Materials for Nanotechnology." This course will be offered to senior year students in Physics, Chemistry, Electrical Engineering, and Chemical Engineering. An outreach program aimed at attracting female high-school students to nanoscience will also be developed in collaboration with the Physics instructor at the LBJ Science Academy, a magnet high school with a large number of minority students. The PI aims to create an opportunity for female students to spend summers with the PI's research group to learn about computational nanoscience. This activity will be coordinated with a successful existing UTEACH program at UT.NON-TECHNICAL SUMMARY:This CAREER award supports computational and theoretical research that aims to develop a theoretical understanding of nanosystems and structures on semiconductor surfaces and education in computational materials research with a focus on undergraduates.The PI will use advanced computational tools that start from the constituent atoms to study how oxide materials can be grown on the surfaces of semiconductors, with an emphasis on materials other than silicon, the current workhorse of the electronics industry. The PI will also study the electronic properties of the resulting nanosystems. The PI will focus on fundamental materials science and surface science problems. The work helps lay the theoretical foundations for semiconductor electronic devices with significantly higher performance and enhanced functionality as compared to current electronic device technology. The PI will also explore new phenomena that may arise in these unusual systems. To bring the excitement of practical theoretical nanoscience into undergraduate education, the PI plans to develop, improve, and enhance a new course entitled "Practicum on Computational Materials for Nanotechnology." This course will be offered to senior year students in Physics, Chemistry, Electrical Engineering, and Chemical Engineering. An outreach program aimed at attracting female high-school students to nanoscience will also be developed in collaboration with the Physics instructor at the LBJ Science Academy, a magnet high school with a large number of minority students. The PI aims to create an opportunity for female students to spend summers with the PI's research group to learn about computational nanoscience. This activity will be coordinated with a successful existing UTEACH program at UT.