Two-Dimensional Motion of Unstable Steps Induced by Flow in Solution

Abstract

By carrying out Monte Carlo simulation, we study step instabilities during crystal growth from solution. In previous studies [M. Sato: J. Phys. Soc. Jpn. 79 (2010) 064606; M. Sato: J. Cryst. Growth 318 (2011) 5; M. Sato: J. Phys. Soc. Jpn. 80 (2011) 024604], we used a one-dimensional model, so that we were unable to study another type of instability, step wandering. In this research, we use a two-dimensional model to study both step wandering and step bunching. When the flow of solutes is in the step-down direction, a regular array of steps is unstable and bunches of steps are formed. Owing to the step bunching, fluctuations along the steps are enlarged and step wandering is induced. If the direction of flow is opposite, a regular array of steps is stable and step bunching does not occur. Although a single straight step is unstable in the case of long-wavelength fluctuations, step wandering does not occur on a vicinal face. Thus, with a step-up flow, the vicinal face is stable against both step bunching a...