Superdiffusive motion of the wetting layer to build the islands. Moving speed of the wetting layer 0.05 nm/sec at 180 K transforming a 4-layer island to a 5-layer island.

M. Hupalo and M. C. Tringides, Phys. Rev. B - Condens. Matter Mater. Phys. 75, 235443 (2007). "Ultrafast kinetics in Pb∕Si(111) from the collective spreading of the wetting layer"