Defect Formation and Crossover Behavior in the Dynamic Scaling Properties of Molecular Beam Epitaxy

Stochastic simulation results, appropriate for Molecular Beam Epitaxy, involving ballistic deposition and thermally activated Arrhenius diffusion of adatoms are presented for one- and two-dimensional substrates, allowing for overhangs and bulk vacancies. The asymptotic Kardar-Parisi- Zhang universality is found to be triggered by a sudden nucleation of large-scale defect formation in the growing film that shows a distinct dependence on dimensionality. The pre-nucleation transient behavior, which may be of experimental relevance due to the low defect content, is associated with standard solid-on-solid universality classes.