Ion beams: creating functionalities and probing interfaces in materials

我提议的研究的中心主题是在电子水平上解开材料的奥秘，重点是量子结构和其他纳米级材料，其电子特性从它们的体类似物中修改。我的小组研究半导体量子点（QD）的原子尺度行为，重点是它们的界面。采用离子束修饰（IBM）和分子束外延（MBE）等先进的制造方法与纳米加工相结合。采用了亚纳米深度分辨率、原子横向分辨率和时域光谱学的表面和界面表征工具。今后五年将致力于三个主要主题：半导体量子结构：量子约束、界面和缺陷态的相互作用。我们已经建立了使用离子束制造硅量子点的专业知识，并将进一步探索这些系统在掺杂时光学和电子特性的差异。我们对光子（可见光或x射线）与这些量子点组件的相互作用感兴趣，这些量子点组件使用光致发光（PL），时间分辨PL和x射线激发光学发光（XEOL）进行研究。特别的努力将给予量子点/矩阵界面的表征和使用各种输运模型的输运性质的描述。这些研究将扩展到非平衡条件下的器件响应，例如，在施加电压或照明下。这项工作的结果将对半导体科学技术、发光结构和未来一代用于信号传输和处理的超快设备产生直接影响。2. 电浆效果。我们的目标是实现金属纳米粒子（Al, Au）和非金属IV族等离子体系统的可控等离子体响应。通过使用MBE和IBM，我们将设计和制造等离子体结构，这些等离子体结构将被优化为在紫外/可见光和短波长的红外范围内工作。我们将重点关注以下几个问题。等离子体频率是否可以通过MBE生长与纳米制造和IBM相结合来控制？几何形状对等离子体结构的影响是什么？如何更好地控制受限模式？这些研究成果将适用于量子和化学传感。3. 超高分辨率离子深度剖面和原位能力。我们将重点介绍高分辨率离子束分析在电化学过程中的原位应用。新的原位装置将被设计和应用于研究钝化膜在金属表面的生长机制、多层金属结构的腐蚀以及锂离子和钠离子电池中的界面效应。新设计的原位电池使我们有机会在循环电化学电池的同时进行高分辨率深度分析。对反应机理的进一步了解将提高电极的性能，改善钝化膜的性能，提高防腐性能。

The central theme of my proposed research is unravelling the mystery of materials on the electronic level, with focus on quantum structures and other nanoscale materials, with the electronic properties modified from their bulk analogues. My group studies atomic-scale behavior of semiconductor quantum dots (QD) with emphasis on their interfaces. Advanced fabrication methods such as ion beam modification (IBM) and molecular beam epitaxy (MBE) combined with nanofabrication are used. Surface and interface characterization tools with sub-nanometer depth resolution, and the atomic lateral resolution as well as time-domain optical spectroscopy are employed. Three major themes will be pursued in the next five years: 1. Semiconductor quantum structures: interplay of quantum confinement, interface and defect states. We have established expertise in the fabrication of silicon QDs using ion beams and will further explore the difference in optical and electronic properties of these systems when doped. We are interested in the interactions of photons (visible or X-ray) with these QD assemblies studied using photoluminescence (PL), time-resolved PL and X-ray excited optical luminescence (XEOL). Special effort will be given to characterization of the QDs/matrix interfaces and description of the transport properties using various transport models. These studies will be extended to device response under non-equilibrium conditions, e.g., with applied voltage or under illumination. The results of this work will have immediate impact on semiconductor science and technology, light-emitting structures and the future generation of ultra-fast devices for signal transmission and processing. 2. Plasmonic effects. Our goal is to achieve controllable plasmonic responses for metal nanoparticles (Al, Au) and non-metal group IV plasmonic systems. By using MBE and IBM, we will design and fabricate plasmonic structures that will be optimized to operate in the UV/visible and short wavelength IR range. We will focus on the following key questions. Can plasma frequency be controlled through MBE growth combined with nanofabrication and IBM? What are the effects of geometry on plasmonic structures? How to better control the confined modes? The outcome of these studies will be applicable in quantum and chemical sensing. 3. Ultra-high resolution ion depth profiling and in-situ capabilities. We will focus on in-situ application of high-resolution ion beam analysis to electrochemical processes. New in-situ devices will be designed and employed to study the mechanisms of passive film growth on metals, corrosion in multilayer metal structures and interface effects in Li- and Na-ion batteries. New designs of in-situ cells give us opportunities to perform high-resolution depth analysis while cycling the electrochemical cells. An improved understanding of reaction mechanisms will lead to higher performance of electrodes, better passive films, more advanced corrosion protection.