The interlayer diffusion of Au atoms from Au islands grown on Ir(111) was investigated via scanning tunnelling microscopy and kinetic Monte Carlo simulations. The scanning tunnelling microscopy measurements revealed that the first Au layer on Ir(111) grows in a complete layer at 100K, whereas the Au layer grows in a three-dimensional fashion from the second Au layer at this temperature. Annealing these surfaces to 300K reduces the higher-layer islands, indicating that Au atoms undergo step-down diffusion. By measuring the density of the top-layer islands and comparing them with the kinetic Monte Carlo simulation results, the additional step-down diffusion barrier for Au atoms to descend from the Au islands was estimated to be 0.02eV on the first Au layer and 0.04eV on the second Au layer. The layer dependence of the additional step-down diffusion barrier was explained in terms of the lattice mismatch between Au and underlying layers.

Interlayer Diffusion of Au Atoms in a Heteroepitaxial System. S.Ogura, K.Fukutani: Journal of Physics - Condensed Matter, 2009, 21[47], 474210