Decay of Cu adatom islands on Cu(111)

We have investigated the decay of Cu adatom islands on Cu(111) as a function of temperature using scanning tunneling microscopy. By comparing the experimental results with the theory of Ostwald ripening and with numerical simulations we find that the decay is limited by the diffusion of adatoms on the terrace. From the decay rate at constant island size as a function of temperature, the sum of the energy for the formation of an adatom on the terrace and the activation energy for diffusion on the terrace is found to be 0.78±0.04 eV. The local environment has a significant influence on the shape of the island area versus time curves. An optimum match between simulations and experiment for the shape of the decay curves is achieved for a line tension of the islands of 0.45 eV per atom length. The Schwoebel-Ehrlich barrier for the hopping of atoms over a step is determined to be about 0.12 eV by matching the relative decay times of islands on small terraces to the simulations.