Extracting site-specific reaction rates from steady state surface morphologies: Kinetic Monte Carlo simulations of aqueous Si(111) etching

The etching of Si(111) surfaces is studied using a chemically realistic, kinetic Monte Carlo simulation that incorporates the full surface geometry. These simulations show that reliable, site-specific reaction rates can be extracted from steady state etched surface morphologies. The kinetics of pit etching and step etching are examined separately and in concert. Comparisons are made to mean field approximations; however, mean field kinetics are shown to be quantitatively incorrect in their predictions of surface morphology. Statistical parametrizations of surface morphology, such as local width measurements, are also examined. Although these parametrizations are sensitive to the relative etch rates, they cannot be used to ascertain the actual etch mechanism. In general, steady state etch morphologies change gradually as the relative etch rates are varied over three-to-five decades of reactivity. Within this range, a change in surface morphology is observable when a single etch rate is changed by a factor of 2–3.