Monte Carlo study of kinetic smoothing during dissolution and etching of the Kossel (100) and silicon (111) surfaces

Abstract

We have analyzed the asymmetry between growth and dissolution using Monte Carlo simulations of flat and vicinal (100) surfaces of a Kossel crystal. We find that at a high driving force dissolution is very anisotropic and nearly atomically flat surfaces are produced, if the nearest-neighbor bond strength is sufficiently large. This effect we call kinetic smoothing. For wet-chemical etching of the Si(111) surface, the chemical-etch reaction determines the annihilation rate constants. If the differences between the rate constants for removal of atoms from kink, step, and terrace sites are large enough, then we observe smooth surfaces and anisotropic etching, i.e., kinetic smoothing. If etching is anisotropic, knowledge of the annihilation rate constants suffices to find an analytical expression for the etch rate as a function of misorientation. This expression can be used to fit experimental etch rates for etching of vicinal Si(111) in potassium hydroxide.