Phase-field modeling of anomalous spiral step growth on Si(001) surface

Motivated by recent experimental results on anomalous spiral step motion on Si (001) surfaces, we use a phase-field model to understand the observed growth mode. The developed phase-field model allows simulation of step motion and surface phase switching for growth and sublimation. Our simulated results reproduce the anomalous spiral step motion on the Si (001) surfaces. Furthermore, we investigate the step dynamics in terms of the steady-state spiral shape for possible strain distributions and a large range of deposition rates. The obtained scaling law of the step spacing as a function of the deposition rate is different from earlier results for conventional spiral step growth, and indicates a crossover toward the local step dynamics due to the strain field of the screw dislocation on the Si(001) surfaces.