Island Diffusion and Coarsening on Metal (100) Surfaces

The diffusion and coarsening of two-dimensional homoepitaxial islands on Cu(100) and Ag(100) surfaces have been studied at room temperature with time-sequenced scanning tunneling microscopy. Quantitative analyses of the dependence of island diffusion coefficient $D$ vs the island side length $L$, $D\propto L^{-\alpha }$, yield noninteger scaling exponents which are consistent with island coalescence. Moreover, the near absence of island decay shows that the island diffusion occurs via mass transport along the island periphery.