Atomistics of Kinks and Surfactants

9526100 Spence这个项目主要研究半导体中位错运动的基本原子过程，以及表面活性剂在控制逐层外延晶体生长中的作用机制。重点研究两个方面：(1)利用原子分辨电子显微镜在600℃下用“禁止”反射TEM晶格成像直接观察运动中的扭结对位错的影响；扭结的钉钉机制和扭结在不同部分位错上的相关性，以及在原子水平上最终控制晶体延展性的因素是基本的兴趣。(2)最近开发的扫描原子探针（SAP）允许从STM图像中识别位点的原子群喷射到飞行时间质量分析仪中进行化学鉴定，将用于研究表面活性剂在Ge on Si生长过程中的作用，并测试表面活性剂在低温外延生长早期阶段的作用理论。理论分析，例如，扭结迁移率的从头计算，是该项目的一个组成部分。扫描原子探针（SAP）是近年来发展起来的一种新型探针，将用于表面活性剂在电子和光子材料外延晶体生长过程中的中介作用的基础研究。SAP和高分辨率电子显微镜都将用于研究原子缺陷的运动，以及最终控制宏观材料特性的额外原子水平现象。该计划的一个重要特点是在一个基础和技术意义重大的领域培养研究生和本科生。* * *。

9526100 Spence This project addressees research into fundamental atomic processes responsible for dislocation motion in semiconductors, and into the mechanism of surfactant action in controlling layer-by-layer epitaxial crystal growth. Two research aspects being emphasized are: (1)direct observation of kinks in motion on dislocations by atomic resolution electron microscopy using "forbidden" reflection TEM lattice imaging in silicon at 600C; pinning mechanisms of kinks and the correlations of kinks on different partial dislocation, and factors which ultimately control the ductility of crystals at the atomic level are of basic interest. (2) a recently developed Scanning Atom Probe (SAP) which allows groups of atoms from identified sites in an STM image to be ejected into a time-of-flight mass analyzer for chemical identification, will be used to study surfactant action during the growth of Ge on Si, and to test theories of surfactant action in the early stages of low-temperature epitaxial growth. Theoretical analyses, e.g., ab-initio computations of kink mobility, are an integral part of the project. %%% A Scanning Atom Probe (SAP) has recently been developed and will be used for basic research studies of surfactant mediation during epitaxial crystal growth of electronic and photonic materials. Both SAP and high resolution electron microscopy will be used to study the motion of atomic defects, and additional atomic level phenomena that ultimately control macroscopic material properties. An important feature of the program is the training of graduate and undergraduate students in a fundamentally and technologically significant area. *** .