Step-mediated island growth: a new ripening mechanism

Two types of islands have grown on a Co-deposited Si(111)-(5$\times $2)/Au vicinal surface: islands grow on terraces (terrace islands) and on top of a step (step islands). The terrace islands follow the classical Ostwald ripening process. For step islands, their density remains unchanged as the average size grows to a limit of $\sim $ 650 \textit{nm}$^{3}$. Furthermore, an ordering of step islands gives a ratio of $\sim $ 0.25 between the average island width and island-island separation. We attribute this unique growth to the vertical lattice mismatch created by the height difference between two halves of an island separated by a step.