Step-edge barriers: Truths and kinetic consequences

Observations of individual atoms on metal surfaces have shown that the diffusion potential at descending steps is not the simple repulsive barrier usually assumed in crystal growth. Instead, atoms may be held in asymmetric traps at step edges, and there are significant distortions of the potential near ascending steps. That the presence of step-edge traps instead of repulsive barriers can have a crucial effect on atomic kinetics is demonstrated by analyzing three processes important in crystal growth: the lifetime of atoms before incorporating into a cluster, dissociation of atoms from lattice steps, and incorporation on vicinal surfaces.