Quantum Dot Patterning for Tailored Properties

技术：该项目寻求对外延量子点纳米结构演化的基本了解。预计这项研究的结果将提供以下方面的见解：是什么控制了量子点及其附近的形状、应变和化学成分分布；什么因素推动了量子点在不同热力学和动力学条件下的演化；以及定向组装如何通过图案化改变这些结构的性质。这项研究将受益于新的进展，表明直接X射线相位恢复方法可以无损地探测外延量子点的三维结构、化学和应变分布。该计划将相干布拉格棒分析(COBRA)映射技术应用于各种量子点系统，包括通过STransky-Krastanov生长和液滴外延进行的自组装，以及新颖的定点定向组装方法。通过聚焦离子束图案化以及在电子束光刻制作的图案化模板上生长纳米结构，将实现对图案化点阵的深入的X射线同步研究。与自组装量子点相比，定点沉积量子点有可能极大地改善量子受限材料的成分和几何均匀性？这一局限性一直阻碍着量子点的广泛应用。将最先进的材料生长和沉积技术与先进的X射线相重构技术相结合，有望提供控制关键生长参数的手段，定量测量它们对量子点结构的影响，并利用这些信息来设计所需的性能。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为半导体量子点系统的新理解和能力贡献基础材料科学知识，这些系统有助于改进现有的半导体器件技术，如激光和探测器，特别是用于电信和太阳能应用。量子点系统也可能成为未来应用领域的一项使能技术，例如量子计算和单电子设备。该项目为研究生培训提供了研究机会，包括在国家设施(高级光子源)的经验，也为更多的初级学生和代表性不足的群体提供了培养他们对科学和工程的兴趣的机会。从初中到本科生，专业人士都积极参与外展活动。他们整合了与社会需求产生共鸣的实践活动；例如，他们规划了关于替代能源应用的新课程，并正在与创新的数据共享信息学合作。

Technical: This project seeks fundamental understanding of the evolution of epitaxial quantum dot nanostructures. It is anticipated that the outcome of this research will provide insights on what controls the shape, strain, and chemical composition profile in the dot and its vicinity; what factors drive the evolution of quantum dots under different thermodynamic and kinetic conditions; and how directed-assembly, by patterning, can alter the properties of these structures. This study will benefit from new developments demonstrating that direct x-ray phase retrieval methods can non-destructively probe the 3D structure, chemical and strain distributions of epitaxial quantum dots. The plan is to apply Coherent Bragg Rod Analysis (COBRA) mapping techniques to a variety of quantum dot systems, including self-assembly by Stransky-Krastanov growth and droplet epitaxy, as well as novel site directed assembly methods. In-depth x-ray synchrotron studies of patterned dot arrays will be achieved by Focused Ion Beam patterning as well as nanostructure growth on patterned templates made by electron-beam lithography. Site directed deposition of quantum dots has the potential to greatly improve the compositional and geometrical uniformity of quantum confined materials, compared to self assembled dots?this limitation has been holding back widespread implementation of quantum dots for applications. The combination of state-of- the-art materials growth and deposition with advanced x-ray phase reconstruction techniques is expected to provide the means to control critical growth parameters, quantitatively measure their effects on quantum dot structures, and use this information to engineer desirable properties. 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 for semiconductor quantum dot systems of interest for improving existing semiconductor device technologies, such as lasers, and detectors, especially for telecommunications and solar applications. Quantum dot systems may also be an enabling technology for future areas of application such as quantum computing and single electron devices. The project offers research opportunities for graduate training, including experience at national facilities (Advanced Photon Source), and also for more junior students and under-represented groups to develop their interests in science and engineering. The PIs are heavily involved in outreach activities, from junior high through undergraduate research opportunities. They have integrated hands-on activities which resonate with societal needs; for example, they have planned new curriculum on alternate energy applications, and are working with innovative data sharing informatics.