Size-Selecting Semiconductor Templates for Nano-Scale Spatial Control of Self-Assembled Heterostructures

技术。该项目旨在研究如何更好地理解和实现缩小尺寸的材料组合，以及如何成功地将具有更好性能或提供新功能的新材料集成在一起。该项目旨在采用先进的加工方法，在纳米尺度上组织材料，精确放置，具有必要的质量和可靠性，例如，实现涉及单电子隧道效应（晶体管，存储器，量子细胞自动机）的新型器件结构的概念，量子计算架构，以及用于高速通道或光学器件的III-V材料与IV组衬底的集成。单独的自组装方法可以在这些长度尺度上排列结构，但不能将结构放置在特定的位置。该方法是将自组装与自上而下的模式方法相结合，以指导生长。该项目旨在通过“应变工程”机制创建由统一和尺寸选择特征组成的地形模板。然后，这些模板将通过模板上的自组装方法，在衬底的特定位置上形成高质量的结晶纳米结构。这有望为创造具有任意横向排列的新结构提供一条途径，并有可能将晶格不匹配的材料与硅结合起来，这是通过高质量的薄膜生长无法实现的。应变的SixGe1-x层将生长在硅衬底上，这些衬底使用聚焦离子束在特定位置进行局部修饰，从而在每个位置形成具有特征尺寸的金字塔形坑，这取决于应变。坑的边缘将被用来提供四个紧密间隔的成核点。研究了在超高真空溅射的异质外延生长过程中，不同的图案化参数和动力学对模板形成的影响。研究还将确定如何使用这些模板来影响不同动力学条件下不同材料的生长。晶格错配半导体（锗硅）以及其他材料如硅化物的生长将被探索。将进行表征研究，以了解对所得形貌、晶体/界面结构、组成和均匀性的影响。会影响电性能和设备应用的潜在用途的项目。这些研究还将包括在技术上重要的材料系统中，非常小的表面不连续、缺陷或杂质对成核过程的影响。非技术。本项目涉及电子/光子材料科学中具有技术相关性的主题领域的基础研究问题。除了研究生参与外，本科生也将直接参与并获得使用先进研究工具的实践经验。增加大学生在其教育早期阶段的研究参与将是一个主要重点，并特别鼓励妇女和少数民族。这项本科生研究将被用来帮助将这些活动推广到当地的高中，通过展示实际动手研究的例子，他们将有机会作为工程专业的学生参与其中。将通过为学生提供额外的例子与行业建立联系。本研究的许多方面也将纳入新的纳米技术和电磁特性课程，并作为与其他课程相关的补充研究项目，以更有效地将研究与教育结合起来。

Technical. This project addresses research toward greater understanding and implementing ar-rangement of materials at shrinking dimensions, and the ability to successfully integrate new ma-terials with better properties or materials that would provide new functionalities. The project aims for advanced processing methods that can organize materials at nano-scale dimensions with precise placement having the necessary quality and reliability, for example, to realize concepts for new types of device structures involving single electron tunneling effects (transistors, mem-ory, quantum cellular automata), quantum computing architectures, and integration of III-V ma-terials with group IV substrates for high-speed channels or optical devices. Self-assembly meth-ods alone can arrange structures at these length scales, but cannot place structures at specific lo-cations. The approach is to combine self assembly with a top-down patterning method to direct growth. The project seeks to create topographic templates made up of uniform and size-selecting features through a 'strain-engineering' mechanism. These templates will then be used to nucleate high quality, crystalline nanostructures at specified locations on substrates by self-assembly methods that would occur on the templates. This is expected to provide a route to creating new structures with an arbitrary lateral arrangement and the potential for combining lattice mis-matched materials with silicon that would not be achievable through thin film growth with high quality. Strained SixGe1-x layers will be grown on silicon substrates that have been locally modi-fied at specific sites using a focused ion beam, resulting in pyramidal pit formation at each site with a characteristic size, dependent on strain. The pit edges will be used to provide four closely spaced nucleation sites. Studies will be done on how the template formation is influenced by various patterning parameters and by kinetics during heteroepitaxial growth using ultra high vac-uum sputtering. Studies will also be done to determine how these templates can be used to influ-ence the growth of dissimilar materials under different kinetic conditions. The growth of lattice-mismatched semiconductors (Ge on Si) as well as other materials such as silicides will be ex-plored. Characterization studies will be done to understand the effects on resulting morphology, crystal/interface structure, composition, and uniformity?items which will influence electrical properties and the potential usefulness for device applications. These studies will also include the effect of very small surface discontinuities, defects, or impurities on nucleation processes in technologically important material systems. Non-Technical. The project addresses fundamental research issues in a topical area of elec-tronic/photonic materials science having technological relevance. In addition to graduate student participation, undergraduates will also be directly involved and gain hands-on experience using advanced research tools. Increasing undergraduate research participation at early stages in their education will be a primary focus, with particular encouragement given to women and minori-ties. This undergraduate research will be leveraged to help promote these activities to local high schools, by demonstrating examples of practical hands-on research they will have the opportu-nity to participate in as engineering students. Connections will be made to industry by providing additional examples to students. Many aspects of this research will also be incorporated into new nanotechnology and electromagnetic properties courses and used as supplemental research pro-jects associated with other courses to integrate research and education more effectively.