Abstract:
Interlayer diffusion controls the transfer of atoms between different layers in a film and is the key factor controlling whether growth is layer-by-layer growth or 2-dimensional. Recent experiments on Ag/Ag(111) have measured similar values for the step edge barrier Es but different prefactor ratios vs/vt where vt is the prefactor at a terrace and vs the prefactor at a step edge site. Prefactor ratio larger than 1, vs/vt $>$1, is extracted at low temperature T$<$150K, but vs/vt $\propto $1 is extracted at higher temperature, T=300K experiments. We examine as possible reasons for the discrepancy the dependence of the step edge barriers on the type of microscopic site (i.e. kink or straight step sites). In addition we examine the conditions necessary for steady state to hold in island decay experiments, which are used to conclude vs/vt $\propto $1 and whether such conditions are fulfilled for Ag/Ag(111). Because of the very low terrace diffusion barrier on Ag(111) Et $<$ 0.1eV the steady state condition does not hold and the island decay is better described in terms of independent atom detachment. Re-analysis of the data in terms of this model results also in vs/vt $>$1 in good agreement with the low temperature experiments.