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 b arrier usually assumed in crystal growth. Instead, atoms may be held i n asymmetric traps at step edges, and there are significant distortion s of the potential near ascending steps. That the presence of step-edg e traps instead of repulsive barriers can have a crucial effect on ato mic kinetics is demonstrated by analyzing three processes important in crystal growth: the lifetime of atoms before incorporating into a clu ster, dissociation of atoms from lattice steps, and incorporation on v icinal surfaces. (C) 1997 Elsevier Science B.V.