CAREER: Lateral Composition Modulation in InAs/GaSb Superlattices: Nanometer Sized Quantum Wires

这一职业项目是一项综合的研究、教学和推广活动。该项目的目的是对在分子束外延(MBE)生长InAs/GaSb超晶格、InxGa1-xSb单层和InAs/InxGa1-xSb多层膜过程中通过横向成分调制(LCM)形成的“天然”量子线有基本的了解，这些材料可用于纳米和光电子器件等应用。这项研究可能会对使用InAs/(In)GaSb LCM材料的固态技术的发展产生重大影响，这些材料构成了新的LCM器件的基础，例如基于量子线(QWR)技术的激光器。该研究计划的一个目标是控制液晶纳米结构的形成，即调制程度和调制波长，并解决可重复性问题。这将通过使用迁移增强型外延(MEE)进行分析来有效控制界面成分，因为LCM与界面处的表面起伏有关。另一个目标是用传统的和先进的X射线衍射技术，即平面X射线衍射(XRD)、掠入射衍射(GID)和掠入射小角度散射(GISAXS)来表征调制结构。这些技术将允许在深度/界面分析方面探测LCM结构，这是传统的X射线衍射法所不具备的。横截面透射电子显微镜(XTEM)也将与X射线衍射仪(XRD)结合使用，以产生对LCM物理结构的调查。第三个目标是通过偏振相关的光致发光和磁光致发光来表征这些结构的光学和电学行为，以展示量子线行为，并通过霍尔效应测量来确定未来纳米和光电子器件发展的材料前景。与海军研究实验室(NRL)在这些材料的生长方面建立的合作将极大地提高该项目的成功，并通过暑期实习拓宽和丰富参与该项目的学生的视野，超越PI的实验室的限制。%该项目解决与技术相关的基础材料科学研究问题。该项目的一个重要特点是高度重视教育，并将研究与教育相结合。该教育计划通过四个途径扩展到通常的研究生和本科生活动：(1)开发一门基于固体物理实验技术的课程，以及它在未来纳米技术中的作用，目标是一年级和二年级的物理和工程研究生。本课程将介绍应用于纳米技术的固体物理实验技术，并包括实验室访问和实验演示；(2)为PI实验室的本科生、研究生和博士后助理提供建议将拓宽他们的个人视野，使他们超越单一专业的视野。这些学生还将协助正在开发的实验固态物理课程的实验室演示；(3)通过实验室职位和实验室参观，指导参与Louis Stokes少数族裔联盟计划(LSAMP)的本科生接触固态纳米技术，并在LSAMP年会上发表演讲；以及(4)在当地高中的年度讲座中介绍纳米技术对社会的影响。*

This CAREER project represents an integrated research, instructional and outreach activity. The aim of the project is to gain fundamental understanding of "natural" quantum wires formed by lateral composition modulation (LCM) during molecular beam epitaxial (MBE) growth of InAs/GaSb superlattices, InxGa1-xSb single layers and InAs/InxGa1-xSb multilayers, where these materials may be utilized for applications such as nano- and opto-electronic devices. This research may significantly impact the development of solid-state technologies utilizing InAs/(In)GaSb LCM materials forming the basis for new LCM devices, such as lasers based on quantum wire (QWR) technology. An objective of the research plan is to control the formation of the LCM nanostructures, i.e., degree of modulation and modulation wavelength, and address re-producibility issues. This will be done through analysis using migration-enhanced epitaxy (MEE) to effectively control interfacial composition since LCM is associated with a surface undulation at the interface. Another objective is to structurally characterize the modulated structures by conventional and advanced x-ray diffraction techniques, i.e., in plane x-ray diffraction (XRD), grazing-incidence diffraction (GID) and grazing-incidence small-angle scattering (GISAXS). These techniques will allow probing of the LCM structures in terms of depth/interface analysis, not available through conventional XRD. Cross sectional transmission electron microscopy (XTEM) will also be used in conjunction with XRD to yield a survey of the physical structure of the LCM. A third objective is to characterize the optical and electrical behavior of these structures by polarization dependent photoluminescence and magneto-photoluminescence to demonstrate quantum wire behavior, and Hall effect measurements to determine the materials prospect for future nano- and opto-electronic device development. An established collaboration with the Naval Re-search Laboratory (NRL) on the growth of these materials will greatly enhance the success of the project and broaden and enrich the perspectives of students involved in the project beyond the confines of the PI's laboratory through summer internships. %%% The project addresses fundamental materials science research issues having technological relevance. An important feature of the project is the strong emphasis on education, and the integration of research and education. The educational plan extends beyond usual graduate and under-graduate student activities via four avenues: (1) Development of a course based on experimental techniques in solid-state physics and its role in the future of nanotechnology targeted toward first and second year physics and engineering graduate students. This course will introduce experimental techniques of solid-state physics as they apply to nanotechnology as well as include laboratory visits and experimental demonstrations; (2) Advising undergraduate, graduate and post-doctoral associates in the PI's laboratory will broaden their individual perspectives beyond that of a single specialty. These students will also assist with laboratory demonstrations for an experimental solid-state physics course being developed; (3) Mentoring and exposing undergraduate students involved in the Louis Stokes Minority Alliance Program (LSAMP), to solid-state nanotechnology through laboratory positions and laboratory tours as well as presenting lectures at the LSAMP annual conference and (4) Yearly lectures at local high schools on the impact of nanotechnology on society.***