Engineering Interfaces in No-Common-Atom Heterostructures

提出了一项为期一年的短周期超晶格(SPS)的合成和原子级表征的研究计划，其中各组成层不共享同一元素。这些非公共原子系统，如InAs/GaSb，在红外光电子学技术中的应用引起了人们的极大兴趣，为通过操纵低对称性的界面结构来调节电子能带结构提供了可能性。我们的目标是了解合成具有明确界面结构的非公共原子SPS所需的外延生长条件和工艺。这需要对界面形成的原子机制进行高水平的控制，并具有用原子分辨率表征界面结构的能力。该项目的一个独特特点是使用一种新的直接方法来使用X射线同步辐射对埋藏的界面进行成像。这种技术，相干布拉格棒分析(COBRA)，能够非破坏性地提供具有亚埃分辨率的原子位置的外延薄膜结构的三维图谱。眼镜蛇图谱将被用来寻找足够详细的结构和成分信息，以控制生长条件，使特定的界面结构具有定制的光电特性。界面成分分布的理论预测可以与实验确定的界面结构相比较。这些动力学模型将对实验起到有用的指导作用。该项目解决具有高度技术相关性的电子材料专题领域的基础研究问题。非公共原子短周期超晶格(SPS)系统固有的电子性质的可调性可能会影响到存在重要社会需求的领域的红外器件技术，例如在医疗保健、通信和国家安全方面。该项目的一个重要内容是通过在一个基础和具有重要技术意义的领域对学生进行培训，将研究和教育结合起来。该项目为研究生培训提供了令人兴奋的研究机会，也为更多的低年级学生对科学和工程产生兴趣。已经制定了一个研究活动方案，该方案与拟议的研究相结合，但经验较少的学生也可以接触到。国家研究设施(高级光子源)的使用将使学生接触到材料研究的前沿项目，并提供与不同领域的广泛教育和培训活动联网的机会。密歇根州立大学与霍华德大学在高级光子源的联合束线部门是鼓励来自代表性不足群体的学生参与研究的焦点。***

A one-year program of research is proposed on the synthesis and atomic level characterization of short period superlattices (SPS) in which the constituent layers do not share a common element. These no-common-atom systems, such as InAs/GaSb, have attracted significant interest for applications in infrared optoelectronics technology, offering the possibility to tune electronic band structure by manipulating the low-symmetry interface structure. The goal is to achieve understanding of the epitaxial growth conditions and processes required to synthesize no-common-atom SPS with well-defined interface structures. This calls for a high level of control over atomistic mechanisms of interface formation and the ability to characterize the interface structure with atomic resolution. A unique feature of the project is the use of a novel direct method to image buried interfaces using x-ray synchrotron radiation. This technique, Coherent Bragg Rod Analysis (COBRA), is capable of providing, non-destructively, a three-dimensional map of epitaxial thin-film structures with sub-Angstrom resolution of atomic positions. COBRA maps will be used to seek sufficiently detailed structural and compositional information to control growth conditions enabling specific interface structures with tailored optoelectronic properties. Theoretical predictions of the interface composition distributions are available with which experimentally determined interface structures can be compared. These kinetic models will serve as a useful guide for experiments. %%% The project addresses basic research issues in a topical area of electronic materials with high technological relevance. The tunability of electronic properties inherent in no-common-atom short period superlattices (SPS) systems may impact infrared device technology in areas where there are important societal needs, for example in health care, communications, and national security. An important element of the project is the integration of research and education through the training of students in a fundamental and technologically significant area. The project offers exciting research opportunities for graduate training and also for more junior students to become interested in science and engineering. A program of research activities which are integrated with the proposed research, but which are also accessible to less experienced students has been devised. The use of national research facilities (Advanced Photon Source) will expose students to forefront programs in materials research, and provide opportunities to network with a broad range of educational and training activities in different fields. The U. MI joint Beam Line Sector with Howard University at the Advanced Photon Source is a focal point for encouraging research participation of students from underrepresented groups. ***