Atomistic modeling of morphological evolution during simultaneous etching and oxidation of Si(1 0 0)

Prolonged exposure of Si(100) surfaces to oxygen produces: etching at high temperatures (T) characterized by the formation of monolayer-deep elliptical etch pits in successive layers (active oxidation); simultaneous etching and formation of oxide-capped Si-nanoprotrusions at moderate T (transition regime); and rapid coverage of the substrate by an oxide layer at low T (passive oxidation). We develop an atomistic model with the goal of describing evolution of the complex far-from-equilibrium surface morphology for a range of temperatures above and into the transition regime under conditions where etching dominates oxidation. Model development is guided by experimental observations, by general concepts from nucleation theory for the formation of etch pits and oxide islands, and by input from ab-initio quantum chemistry calculations for key aspects of the oxygen adsorption and SiO desorption energetics.