Atomistics of Kinks and Surfactants

9526100 Spence该项目致力于研究半导体中位错运动的基本原子过程，以及控制逐层外延晶体生长的表面活性剂作用机制。 重点研究了两个方面：（1）利用原子分辨电子显微术，在600 ℃下利用“禁戒”反射TEM晶格成像技术，直接观察位错上运动的扭结;扭结的钉扎机制和不同部分位错上扭结的相关性，以及最终控制晶体延展性的因素，是原子水平上的基本兴趣。 (2)最近开发的扫描原子探针（SAP）允许从STM图像中识别的位点中的原子组被喷射到飞行时间质量分析器中用于化学识别，其将被用于研究在Si上生长Ge期间的表面活性剂作用，并且用于测试低温外延生长的早期阶段中的表面活性剂作用的理论。 理论分析，例如，扭结流动性的从头计算是该项目的组成部分。扫描原子探针（SAP）最近已经开发出来，并将用于电子和光子材料外延晶体生长过程中表面活性剂介导的基础研究。 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其他原子级现象。 该计划的一个重要特点是在一个基本的和技术上重要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. *** .