Strain at surface and interface steps

Abstract

Transmission Electron Microscopy (TEM) is a powerful tool for the study of interface and surface phenomena. Its sensitivity to lattice plane orientation allows for the imaging of crystal strain. In this thesis, I will present a unique method for quantitatively measuring crystal strain using TEM. This method relies on the quantitative comparison of experimental and simulated dark field images. Employing this technique has allowed for the measurement of strain at surface and interface steps for the first time. It will be shown that a Si(111) 7 x 7 surface step possesses appreciable long range strain. This strain increases by more than an order of magnitude for Si(111)/Ge and Si(111)/SiO$\sb2$ interface steps. The presence of strain has important consequences for surface and interface properties, and these are briefly discussed.