Ion beams: creating functionalities and probing interfaces in materials

我提出的研究的中心主题是在电子水平上揭开材料的神秘面纱，重点是量子结构和其他纳米材料，其电子性质从它们的大块类似物中修改。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。先进的制造方法，如离子束改性（IBM）和分子束外延（MBE）与纳米纤维相结合。表面和界面表征工具，亚纳米深度分辨率，原子横向分辨率以及时域光谱。在未来五年内，我们将继续致力于三大主题：1.半导体量子结构：量子限制、界面与缺陷态的相互作用。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的光学和电子特性的差异。我们感兴趣的是光子（可见光或X射线）与这些量子点组件的相互作用研究使用光致发光（PL），时间分辨PL和X射线激发的光学发光（XEOL）。特别的努力将被赋予量子点/矩阵接口和使用各种传输模型的传输特性的描述的表征。这些研究将扩展到非平衡条件下的器械响应，例如，施加电压或在照明下。这项工作的结果将对半导体科学和技术，发光结构以及未来一代用于信号传输和处理的超快速器件产生直接影响。2.等离子体效应我们的目标是实现可控的金属纳米粒子（Al，Au）和非金属IV族等离子体系统的等离子体响应。通过使用MBE和IBM，我们将设计和制造等离子体结构，这些结构将被优化以在UV/可见光和短波长IR范围内操作。我们将重点关注以下关键问题。等离子体频率可以通过MBE生长结合纳米纤维和IBM来控制吗？几何形状对等离子体结构有什么影响？如何更好地控制受限模式？这些研究的结果将适用于量子和化学传感。3.超高分辨率离子深度剖析和原位能力。我们将着重于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用于研究金属上的钝化膜生长、多层金属结构中的腐蚀以及锂离子和钠离子电池中的界面效应的机制。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的深度分析。提高对反应机理的理解将导致更高的电极性能，更好的钝化膜，更先进的防腐蚀。

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.