Grazing-incidence metal deposition: Pattern formation and slope selection

Molecular beam epitaxy of Cu on Cu(001) at grazing angles of incidence has been studied using spot profile analysis low-energy electron diffraction. A t angles of incidence larger than 50 degrees the evolving surface morpholog y no longer shows the fourfold symmetry inherent to Cu(001), leaving only t he plane of incidence as a mirror plane. The surface roughness as well as t he slope of the grown mound structures increase with increasing deposition angle. These findings are explained by steering, which originates from long -range attractive forces between incident atoms and substrate atoms and lea ds to preferential arrival of atoms on top of islands. Steering is of gener al importance and should routinely be considered in growth studies when the angle of incidence of the depositing beam is larger than 50 degrees.