Low Temperature Growth and Surface Chemistry of Strained Germanium Films on Silicon(100)

本研究关注的是在晶体硅衬底上生长和表征具有2 × 1表面重构的（100）取向的锗薄膜的基本问题。最近的理论和实验研究支持了锗/硅体系的电子能带结构在原子尺度上由于应变和超晶格组成的改变而发生的巨大变化。这个小组已经在室温下生长的硅上的锗薄膜中发现了假晶畴的证据。现在有人提议研究低温下生长在硅上的锗薄膜的结构以及温度的函数。这项工作涉及到分析技术的独特组合：透射离子通道，扫描隧道显微镜，低能电子衍射和俄歇电子能谱。第二个重点将涉及张力锗上附着原子的表面化学。希望人们能够区分化学、几何和应变在确定合原子的键合位置时所起的不同作用。最初，锡和硫将被用作辅助原子。

This research is concerned with fundamental problems involving the growth and characterization of thin heteroepitaxial germanium films on crystalline silicon substrates with a (100) orientation which exhibits a 2 x 1 surface reconstruction. Recent theoretical and experimental studies have given support for dramatic changes in the electronic band structure of germanium/silicon systems resulting from changing the strain and superlattice composition on an atomic scale. This group has found evidence for pseudomorphic domains in germanium films on silicon grown at room temperature. It is now proposed to investigate the structure of thin germanium films on silicon grown at low temperatures and also as a function of temperature. This work involves a unique combination of analytic techniques: transmission ion channeling, scanning tunneling microscopy, low energy electron diffraction, and Auger electron spectroscopy. A second emphasis will involve the surface chemistry of adatoms on strained germanium. It is hoped one can distinguish the seperate roles played by chemistry, geometry, and strain in determining the bonding site of the adatom. Initially tin and sulfur will be employed as adatoms.