Faceted-rough surface in the non-equilibrium steady state near equilibrium

Abstract

Faceted rough surfaces near equilibrium in nucleation limited steady crystal growth is demonstrated using the Monte Carlo method, where “faceted” means the terrace and side surfaces of a macrostep are atomically and thermodynamically smooth at equilibrium due to anomalous surface tension caused by a step–step attraction at sufficiently low temperatures. The surface growth velocity and surface width are calculated as a function of the driving force of crystal growth Δμ for several system sizes L. We found that a faceted rough surface is thermodynamically rough for Δμ larger than the transition point Δμco between two-dimensional (2D) single nucleation and poly-nucleation growth. In the faceted rough regime, surfaces with faceted macrosteps grow in the manner of a step detachment process, due to 2D poly-nucleation at the lower edge of a faceted macrostep. In the step detachment growth process, the centre of a faceted macrostep moves in the direction opposite to the growth direction of the elementary steps. The present work demonstrates that since a step detaches to grow both along the terrace and the side surface, the centre of the macrostep keeps the same position. In addition, stacking faults in a grown layer are suppressed as the side and terrace surfaces sustain the crystal structure.