Stranski-Krastanov Growth in a Binary Eutectic System

9705081 Marks这笔赠款旨在从根本上了解半导体上金属薄膜的生长，以期开发包括有限尺寸效应的相图，如降低共晶温度。了解金属与衬底反应时在小尺寸下发生的过程几乎是处女地，即使是像STranski-Krastanov(层和岛)在二元共晶中生长这样简单的系统也是如此。该研究方法将超高真空条件下的透射电子显微镜与更经典的表面表征技术相结合，开发了西北大学的一种新的实验系统，并采用了一些新的技术来获得原子尺度的表面信息。要回答的主要问题是：(1)原子尺度的表面结构是什么？(2)表面缺陷的原子尺度细节是什么，如磁区和异相界，而不仅仅是最外层的原子层？(3)我们能否建立单分子层和单分子层加小粒子体系(L-10 nm)的相图？(4)如何将这些与粒子尺寸效应、奥斯特瓦尔德熟化和动力学现象结合起来？多年来，半导体上的金属在科学和技术上都引起了极大的兴趣。%随着金属膜区尺寸的减小(由于实现更高密度的驱动和诸如量子器件等新应用)，不再可能忽略有限尺寸效应。本节目探索与这类电影相关的成长现象。***

9705081 Marks This grant aims at a fundamental understanding of the growth of metal films on semiconductors, with a view towards developing phase-diagrams which include finite size effects such as the depression of the eutectic temperature. Understanding the processes taking place at small sizes when the metal reacts with the substrate is almost virgin territory, even for as simple a system as Stranski-Krastanov (layer plus island) growth in a binary-eutectic. The research approach combines transmission electron microscopy under ultra-high vacuum conditions with more classic surface characterization techniques, exploiting a new experimental system at Northwestern University with some new techniques for obtaining atomic scale surface information. The primary questions to be answered are: (1) What are the atomic scale surface structures? (2) What is the atomic scale detail of surface defects such as domain and heterophase boundaries, not just at the outermost atomic layer? (3) Can we build phase diagrams of the monolayer and monolayer plus small particle regimes (l-10nm)? (4) How do we combine these with particle-size effects, Ostwald ripening and kinetic phenomena? Metals on semiconductors have been of substantial interest both scientifically and technologically for many years. %%% As the size of the metal film regions decrease (due to both the drive to achieve higher densities and for novel applications such as quantum devices), it is no longer possible to ignore finite size effects. This program explores the growth phenomena associated with such films. ***