Unconventional features of Ag epitaxy on the Si(111)7×7 surface

The population of Ag-occupied half-unit cells (HUC’s) on $\mathrm{Si}\mathrm{}\left(111\right)7\times 7$ surface resulting from growth and annealing experiments is observed by scanning tunneling microscopy. The temperature dependence of Ag-object density and preference in HUC occupation are measured. The results are interpreted with the help of a coarse-grained kinetic Monte Carlo model. The key kinetic mechanisms affecting Ag motion are determined, in particular transient mobility of deposited Ag atoms and the existence of a highly stable configuration of six Ag atoms in a HUC. The attempt frequency and barrier to hopping of a single Ag atom between HUC’s are estimated.