THEORY OF SELF-DIFFUSION AT AND GROWTH OF AL(111)

We studied the self-diffusion at clean, flat, as well as stepped, Al(111) surfaces using density-functional theory. There are two important steps on fcc (111) surfaces, typically labeled according to their {111} and {100} microfacets. We calculated the formation energies of these steps, and analyzed the diffusion perpendicular and parallel to them. We discuss the general profile of the diffusing-atom potential-energy surface and identify the role of ''normal'' hopping and exchange mechanisms of diffusion at steps. From these results equilibrium shape of islands and the temperature dependence of the island shapes under growth conditions are predicted.