Surfactant-induced layer-by-layer growth of Ag on Ag(111)

We have investigated the epitaxial growth of Ag(111) by x-ray reflectivity experiments. In the temperature range from 175 to 575 K the growth mode changes gradually from three-dimensional to step flow, but at no temperature was layer-by-layer growth observed. Submonolayer deposits of Sb on the starting surface dramatically alter the growth behavior. With Sb the Ag grows layer by layer over the entire temperature range investigated (225--375 K), resulting in smoother surfaces at the lowest growth temperatures. We propose that Sb decreases the barrier for interlayer diffusion.