Pinning of steps near equilibrium without impurities, adsorbates, or dislocations
Discontinuous surface tension of a vicinal surface is calculated numerically based on a statistical mechanical method. The microscopic model is a restricted solid-on-solid (RSOS) model with a point-contact type step–step attraction (p-RSOS model). The discontinuity in the surface tension leads to step faceting at low temperatures near equilibrium, where macrosteps with smooth side surfaces are formed, resulting in two-surface coexistence. Using the Monte Carlo method with the Metropolis algorithm, we show the formation of the merged steps (macrosteps) and the slow velocity of the merged steps. We demonstrate that steps on a vicinal surface are pinned without impurities, adsorbates, or dislocations. We also propose simple ideas to avoid non-uniform growing of a crystal caused by the discontinuous surface tension of the crystal. • Surface tension becomes discontinuous at low temperatures for sticky steps. • The discontinuous surface tension results in the faceted macrosteps. • The motion of a faceted macrostep is almost inhibited near the equilibrium state. • Locally merged steps pin the single-height steps.