Engineering Interfaces in No-Common-Atom Heterostructures

提出了一个为期一年的研究计划，在短周期超晶格（SPS）的组成层不共享一个共同的元素的合成和原子水平上的表征。这些非共原子系统，如InAs/GaSb，在红外光电子技术中的应用引起了极大的兴趣，提供了通过操纵低对称界面结构来调节电子能带结构的可能性。目标是了解合成具有明确界面结构的无共原子SPS所需的外延生长条件和工艺。这就要求对界面形成的原子机制进行高水平的控制，并能够以原子分辨率表征界面结构。该项目的一个独特之处是使用了一种新的直接方法，利用X射线同步辐射对掩埋界面进行成像。这种技术，相干布拉格棒分析（COBRA），是能够提供，非破坏性的，三维地图的外延薄膜结构与亚埃分辨率的原子位置。COBRA地图将被用来寻求足够详细的结构和成分信息，以控制生长条件，使特定的界面结构与定制的光电性能。理论预测的界面组成分布与实验确定的界面结构可以进行比较。这些动力学模型将作为一个有用的指导实验。该项目解决了具有高技术相关性的电子材料专题领域的基础研究问题。非共原子短周期超晶格（SPS）系统中固有的电子特性的可调谐性可能会影响具有重要社会需求的领域（例如医疗保健，通信和国家安全）中的红外器件技术。该项目的一个重要内容是通过在一个基础和技术重要领域培训学生，将研究与教育结合起来。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感兴趣。一个研究活动的计划，这是与拟议的研究相结合，但也是访问经验不足的学生已经设计。国家研究设施（先进光子源）的使用将使学生接触材料研究的前沿项目，并提供机会与不同领域的广泛教育和培训活动建立联系。联合MI与霍华德大学在先进光子源的联合光束线部门是鼓励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. ***