Non-equilibrium Interface and Surface Dynamics

The Chemical Control of Nanoscale Si(100) Morphology

Melissa A. Hines

Cornell University

The evolution of surface morphology during chemical etching is an inherently multiscale problem in which atomic-scale chemical reactions lead to the development of characteristic features on atomic, mesoscopic and even macroscopic scales. From a chemist?s standpoint, the study of these morphologies yields fascinating insights into surface chemistry, as etching reactions literally write a record of their reactivity in the etched surface. I will discuss the formation of a variety of morphological features on etched Si(100) surfaces that were studied with a combination of morphological probes (e.g., STM, AFM, SEM), chemical probes (e.g., infrared spectroscopy), and kinetic Monte Carlo simulations. I will show that subtle changes in chemistry lead to dramatic morphological changes ? from striped, near-atomically-flat surfaces to surfaces covered with dense arrays of self-propagating pyramids. Although many questions remain unanswered, I will discuss our current understanding of the chemical origins of these features. In contrast to the more commonly studied Si(111) surface, the reactivity of the (100) face is dominated by interadsorbate strain, which leads to long-range correlations in the etch morphology.