AVS 45th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS1-WeA

Paper SS1-WeA8
Edge Barriers and Mass Transport on Metal (100) Surfaces@footnote 1@

Wednesday, November 4, 1998, 4:20 pm, Room 308

Session: Electromigration and Surface Transport
Presenter: W.W. Pai, The University of Tennessee
Authors: W.W. Pai, The University of Tennessee
J.F. Wendelken, Oak Ridge National Laboratory
Correspondent: Click to Email
Since epitaxial growth is subject to kinetic limitations, epitaxial growth morphology is usually thermodynamically unstable. These kinetic limitations, in particular the Schwoebel barrier in homoepitaxial systems, often result in a rough, multilevel morphology which begins during deposition of the first monolayer. Post-deposition equilibration of the resultant morphology occurs through several avenues of mass transport. When the starting condition consists of monolayer height islands following a submonolayer deposition at room temperature, coarsening is observed to result from island diffusion and coalescence on Cu(100) and Ag(100) surfaces, where the island diffusion occurs via rapid edge diffusion.@footnote 2@ When a multilevel system results from higher depositions, islands may still diffuse, but this diffusion is inhibited at downhill step edges due to an edge barrier just as the Schwoebel barrier inhibits downhill transport of adatoms. On the (100) surface, this barrier is found to be very high when the step edge is in the close-packed [110] direction, but very low, or even non-existent, when the edge is oriented in a non-close-packed direction. If a diffusing island encounters an edge with such a low barrier, the island may very quickly descend to the lower level with its atoms being incorporated into the step edge in a manner similar to that which has been reported for Cu(111).@footnote 3@ These low barrier sites, in combination with island diffusion and edge diffusion are found to provide the main pathway for smoothening at room temperature on Cu(100) and Ag(100). This is in contrast to the evaporation-condensation mechanism implied by the line tension driven smoothening at higher temperatures on Cu(100).@footnote 4@ @FootnoteText@ @footnote 1@Research performed at ORNL, which is managed by Lockheed Martin Energy Research Corporation for the U.S. DOE under Contract No. DE-AC05-96OR22464 @footnote 2@Woei Wu Pai, Anna K. Swan, Zhenyu Zhang and J. F. Wendelken, Phys. Rev. Lett.79, 3210 (1997).@footnote 3@M. Giesen, G. Schulze Icking-Konert, and H. Ibach, Phys. Rev. Lett. 80, 552 (1998).@footnote 4@J.-K. Zuo and J.F. Wendelken, Phys. Rev. Lett. 70, 1662 (1993).