AVS 46th International Symposium
    Surface Science Division Tuesday Sessions
       Session SS3-TuA

Paper SS3-TuA5
Sulfur's Effect on Cu(111) Surface Morphology

Tuesday, October 26, 1999, 3:20 pm, Room 607

Session: Diffusion on Surfaces
Presenter: J. de la Figuera, Sandia National Laboratories
Authors: J. de la Figuera, Sandia National Laboratories
K. Pohl, Sandia National Laboratories
M.C. Bartelt, Sandia National Laboratories
N.C. Bartelt, Sandia National Laboratories
P.J. Feibelman, Sandia National Laboratories
R.Q. Hwang, Sandia National Laboratories
Correspondent: Click to Email
Numerous studies have demonstrated the dramatic effects that small amounts of an adsorbate can have on film growth and surface morphology. The origin for these effects range from kinetic limitations to thermodynamic considerations. We have recently observed that extremely small amounts of sulfur can significantly affect the smoothing of Cu(111). Cu islands of monolayer height decay several orders of magnitude faster in the presence of ~0.01 ML of sulfur as compared to the clean case. Using time-resolved STM, we have monitored the rate and morphology of the decay to identify the origin of this phenomenon. In agreement with these observations, first-principles calculations predict a dramatic change in the ratio of Cu step formation energies in the presence of a row of S atoms at the steps. Sulfur atoms bind more strongly to the A-type step. The ratio of the equilibrium lengths of the A- and B-type steps is about 1:1.1 on the clean surface, but about 2.4:1 when the step edges are S-saturated. We discuss the observed superfast island decay in terms of atomic processes at and near island edges, including S-mediated near-irreversible detachment of Cu atoms, enhanced diffusion of Cu adatoms and small clusters on the terraces, and more efficient downward transport. This work is supported by the Office of Basic Energy Sciences Division of Materials Sciences of the U.S. DOE (DE-AC04-94AL85000).