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 prenucleation transient behavior, which may be of experimental relevance due to the low defect content, is associated with standard solid-on-solid universality classes.