AVS 45th International Symposium
    Surface Science Division Thursday Sessions
       Session SS-ThP

Paper SS-ThP31
Interlayer Diffusion Near Ledge Contacts: Comparison of Systems with Positive and Negative Schwoebel-Ehrlich Barriers

Thursday, November 5, 1998, 5:30 pm, Room Hall A

Session: Surface Science Division Poster Session
Presenter: L. Yang, Iowa State University
Authors: V. Shah, Iowa State University
L. Yang, Iowa State University
T.L. Einstein, University of Maryland
Correspondent: Click to Email
We present molecular statics studies on the diffusion mechanisms near steps on fcc (111) surfaces. We use the Molecular Dynamics/Monte Carlo-Corrected Effective Medium (MD/MC-CEM) interatomic potential, which has been applied to the study of the Schwoebel-Ehrlich (SE) barriers for single atom diffusion towards a single descending step on Ag, Cu, Au, Pd, Ni, and Pt [Y. Li and A. E. DePristo, Surf. Sci. 351, 189 (1996)]. Among these six transition metals, the MD/MC-CEM potential predicts that Cu and Pd, respectively, have the highest (137 meV) and lowest (-4 meV) SE barriers for interlayer diffusion, via the exchange mechanism at the B-type step. In the present study, we focus on the change in the SE barrier for single- and multi-atom diffusion at descending step edge contacts for two model systems that have positive (Cu) and slightly negative (Pd) SE barriers for atomic diffusion at a single step. We also track the potential surface as an atom approaches corners while diffusing along island edges and as it diffuses away from the step edge on an island plateau. Our results on the behavior of mass transport near ledge contacts will be discussed in the light of recent experimental observations [M. Giesen et al., Phys. Rev. Lett. 80, 552 (1998)]. Two of us (VS and LY) would like to thank members of the Department of Chemistry and the surface physics group at the University of Maryland for their hospitality during our visit there. TLE was supported by NSF-MRSEC at U. of Md.