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

Paper SS1-WeA3
Electromigration and Cluster Motion@footnote 1@

Wednesday, November 4, 1998, 2:40 pm, Room 308

Session: Electromigration and Surface Transport
Presenter: O. Pierre-Louis, University of Maryland, College Park
Authors: O. Pierre-Louis, University of Maryland, College Park
T.L. Einstein, University of Maryland, College Park
Correspondent: Click to Email
We describe the fluctuations, dynamics, and instabilities of adatom and of vacancy single-layer islands during electromigration, generalizing earlier work on straight steps without driving forces.@footnote 2@ We emphasize the dependence on the mass-transport mechanism: periphery diffusion (PD), terrace diffusion (TD), or evaporation-condensation (EC).@footnote 3@ In particular, we find non-circular steady states and derive the cluster diffusion constant D@sub c@. Analytical calculations using Langevin formalism are corroborated by both Monte Carlo simulations and numerical integration. We determine the cluster drift velocity, which in the 3 limiting cases has the size dependence of cluster-area x D@sub c@. In EC, clusters elongate perpendicular to the drift axis. Differences exist in this novel behavior for atom and vacancy clusters. In PD a morphological instability leads to cluster splitting.@footnote 4@ We show that adatom diffusion across the terrace induces a new morphological instability for vacancy clusters and discuss the threshold. Shape fluctuations and D@sub c@ are studied in our Langevin framework. For weak electromigration the cluster responds isotropically for TD or PD but not EC. Fluctuation behavior close to the instability threshold is characterized analytically and numerically. An electric current can also alter attachment/detachment probabilities; novel consequences on cluster dynamics (drift velocity, shape, etc.) are investigated. We discuss experimental relevance of our results. New phenomena should be observed on metal surfaces, and implications for voids in electric lines are discussed. @FootnoteText@ @footnote 1@Work supported by NSF MRSEC grant DMR 96-32521. @footnote 2@O. Pierre-Louis and C. Misbah, Phys. Rev. Lett. 76, 4761 (1996); Phys. Rev. B 58, xxx (1998). @footnote 3@S. V. Khare and T. L. Einstein, Phys. Rev. B 57, 4782 (1998); 54, 11752 (1996). @footnote 4@W. Wang and Z. Suo, J. Appl. Phys.79, 2394 (1996); M. Schimschak and J. Krug, Phys. Rev. Lett. 80, 1674 (1998).