Stranski-Krastanov Growth in a Binary Eutectic System

该资助旨在对半导体金属薄膜的生长有一个基本的了解，以发展相图的观点，包括有限尺寸效应，如共晶温度的降低。了解金属与衬底反应时在小尺寸上发生的过程几乎是一个处女地，即使是像二元共晶中stranski - krstanov（层加岛）生长这样简单的系统。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，利用西北大学的新实验系统和一些新技术获得原子尺度的表面信息。要回答的主要问题是：(1)什么是原子尺度的表面结构？(2)表面缺陷（如畴和异相边界）的原子尺度细节是什么，而不仅仅是最外层的原子层？(3)能否建立单层和单层加小颗粒（l-10nm）的相图？(4)如何将这些与粒径效应、奥斯特瓦尔德成熟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。随着金属膜区域尺寸的减小（由于实现更高密度的驱动和量子器件等新应用），不再可能忽略有限尺寸效应。本节目探讨与此类电影相关的生长现象。＊＊＊

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. ***