Engineering Interfaces in No-Common-Atom Heterostructures

技术：该项目的目标是更好地了解与合成具有明确界面的非公共原子短周期超晶格(SP)相关的外延生长条件和过程-此类超晶格的组成层不共享公共元素。非共原子系统，例如InAs/GaSb，通过操纵低对称性的界面结构来调节电子能带结构，在红外光电子学技术中的潜在应用引起了人们的兴趣。该方法包括识别、理解和控制界面形成的原子机制。原子分辨率表征是该方法的一个基本要素。将研究一种利用X射线同步辐射直接成像埋藏界面的方法。这种名为COBRA的技术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。眼镜蛇图谱将是获得详细的结构和成分信息的关键，有助于理解和控制生长条件，以实现具有所需光电性能的界面结构。界面成分分布的理论预测将与实验确定的界面结构进行比较，并用于指导实验。非技术性：该项目解决具有高度技术相关性的材料科学专题领域的基础研究问题。这项研究将在基础水平上贡献基本材料科学知识，以促进对电子/光子设备的新理解和能力。该计划的一个重要特点是通过在一个具有根本意义和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极好的研究机会，包括在国家设施(高级光子源)的经验，也为更多的初级学生对科学和工程感兴趣。与高中生和本科生合作，PIS制定了一个研究活动计划，该计划与研究相结合，但也适用于经验较少的学生。PI还将组织一个创新的夏令营，以吸引中学女生对科学和工程的兴趣。

Technical: The goal of this project is to achieve greater understanding of epitaxial growth conditions and processes associated with the synthesis of no-common-atom short period superlattices (SPS) with well-defined interfaces-the constituent layers of such superlattices do not share a common element. No-Common-Atom systems, e.g., InAs/GaSb, have attracted interest for potential applications in infrared optoelectronics technology through the possibility of tuning electronic band structure by manipulating low-symmetry interface structures. The approach includes identification, understanding, and control over atomistic mechanisms of interface formation. Atomic resolution characterization is an essential element of the approach. A direct method to image buried interfaces using x-ray synchrotron radiation will be studied. This technique, 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 a key to achieving detailed structural and compositional information useful for understanding and controlling growth conditions for achieving interface structures having desired optoelectronic properties. Theoretical predictions of interface composition distributions will be compared with experimentally determined interface structures, and used to guide experiments. Non-Technical: The project addresses basic research issues in a topical area of materials science having high technological relevance. The research will contribute basic materials science knowledge at a fundamental level to new understanding and capabilities in electronic/photonic 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 project provides excellent research opportunities for graduate training, including experience at national facilities (Advanced Photon Source), and also for more junior students to become interested in science and engineering. Working with high school students and undergraduates, the PIs have devised a program of research activities which are integrated with research, but which are also accessible to less experienced students. The PI's will also organize an innovative Summer Camp to interest middle school girls in science and engineering.