AVS 46th International Symposium
    Surface Science Division Thursday Sessions
       Session SS1+EM+NS-ThA

Paper SS1+EM+NS-ThA9
Diffusion of Lead on the Au(111) Surface Studied by Scanning Tunneling Microscopy and Embedded-Atom Method Molecular Dynamics

Thursday, October 28, 1999, 4:40 pm, Room 606

Session: Metal/Metal Growth
Presenter: M.C. Robinson, Trent University and Queen's University, Canada
Authors: M.C. Robinson, Trent University and Queen's University, Canada
K. De'Bell, University of New Brunswick in Saint John, Canada
A.J. Slavin, Trent University and Queen's University, Canada
Correspondent: Click to Email
Low coverages of Pb deposited on the reconstructed Au(111) surface have been studied with STM and show that the reconstruction strongly influences diffusion and film morphology. Nucleation sites for Pb adatoms are found at the kinks of the reconstruction. For higher coverages, Pb atoms concentrate in the fcc and hcp regions; the elevated transition regions are much less populated. The reconstruction is lifted for some coverage between 0.05 and 0.3 monolayers (ML). For comparison, the Embedded Atom Method-Molecular Dynamics (EAM-MD) method has been used to study diffusion of Pb on both the unreconstructed (flat) and reconstructed surfaces. EAM-MD simulations show that diffusion is complicated by the reconstruction. Using both static and dynamic methods, the diffusion energies have been determined. They show that, for an adatom moving perpendicular to the compression direction, the energy barrier is 1.7 times greater than for motion in the parallel direction. Diffusion is slowed on the fcc part of the reconstructed surface, as compared to the unreconstructed, by a factor of about 2. No greater coverage than 0.07 ML could be forced onto the EAM-modelled reconstructed surface. However, the flat surface could be fully covered, suggesting that the reconstruction is not energetically stable at higher coverages, as has been observed experimentally.