Disassembly of Faceted Macrosteps in the Step Droplet Zone in Non-Equilibrium Steady State

A Wulff figure—the polar graph of the surface tension of a crystal—with a discontinuity was calculated by applying the density matrix renormalization group method to the p-RSOS model, a restricted solid-on-solid model with a point-contact-type step–step attraction. In the step droplet zone in this model, the surface tension is discontinuous around the (111) surface and continuous around the (001) surface. The vicinal surface of 4H-SiC crystal in a Si–Cr–C solution is thought to be in the step droplet zone. The dependence of the vicinal surface growth rate and the macrostep size $\langle n\rangle$ on the driving force $\mathrm{\Delta }\mu$ for a typical state in the step droplet zone in non-equilibrium steady state was calculated using the Monte Carlo method. In contrast to the known step bunching phenomenon, the size of the macrostep was found to decrease with increasing driving force. The detachment of elementary steps from a macrostep was investigated, and it was found that $\langle n\rangle$ satisfies a scaling function. Moreover, kinetic roughening was observed for $\left|\mathrm{\Delta }\mu \right|>\mathrm{\Delta }{\mu }_R$ , where $\mathrm{\Delta }{\mu }_R$ is the crossover driving force above which the macrostep disappears.