The capture of diffusing Ag adatoms, by arrays of 2-dimensional Ag islands deposited onto Ag(100) at room temperature, was studied by using a combination of scanning tunnelling microscopy, kinetic Monte Carlo simulations and diffusion-equation analysis. The dependence of the capture-rates upon Ag-island size was shown to reflect larger island-free regions surrounding the larger islands. That is, there was a strong correlation between island size and separation. This feature, and the effect of the local island environment upon capture, were clarified by introducing suitable tessellations of the surface into so-called capture zones for each island. It was shown that a Voronoi-type tessellation, based upon the distance from the island edges, accurately reflected adatom capture. However, a tessellation which exactly described adatom capture was obtained only from a solution of the steady-state equation which described adatom deposition, diffusion, and capture by an array of islands which were distributed in the same manner as in the experiment. The stochastic nature of adatom capture was also quantified by analyzing the dependence, upon deposition location, of the probability of diffusing adatoms being captured by a specific island. The experimental island-size dependence of adatom capture was found to be entirely consistent with that obtained from a so-called canonical model for the irreversible nucleation and growth of square islands.

Adatom Capture by Arrays of Two-Dimensional Ag Islands on Ag(100). M.C.Bartelt, C.R.Stoldt, C.J.Jenks, P.A.Thiel, J.W.Evans: Physical Review B, 1999, 59[4], 3125-34