18 research outputs found

    Electromigration-Induced Flow of Islands and Voids on the Cu(001) Surface

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    Electromigration-induced flow of islands and voids on the Cu(001) surface is studied at the atomic scale. The basic drift mechanisms are identified using a complete set of energy barriers for adatom hopping on the Cu(001) surface, combined with kinetic Monte Carlo simulations. The energy barriers are calculated by the embedded atom method, and parameterized using a simple model. The dependence of the flow on the temperature, the size of the clusters, and the strength of the applied field is obtained. For both islands and voids it is found that edge diffusion is the dominant mass-transport mechanism. The rate limiting steps are identified. For both islands and voids they involve detachment of atoms from corners into the adjacent edge. The energy barriers for these moves are found to be in good agreement with the activation energy for island/void drift obtained from Arrhenius analysis of the simulation results. The relevance of the results to other FCC(001) metal surfaces and their experimental implications are discussed.Comment: 9 pages, 13 ps figure

    The epitaxy of gold

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    IN SITU ULTRA HIGH VACUUM HIGH ENERGY ELECTRON DIFFRACTION STUDIES. Final Report.

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    Surface characterization of catalytically active metal, alloy, and compound films. Progress report, September 1, 1978--August 31, 1979. [Ag--Cu, Pd--Cu, Pt--Au]

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    Characterization of several catalytically active metal expitaxial systems was carried out. In addition to the Ag/Cu system previously reported, TEM, RHEED, and AES studies were carried out on the Pd/Cu system. Studies were also made on the Pt/Au system. Pd grows on Cu by a monolayer growth mechanism with misfit dislocations at the interface. The thinnest Pd layers are highly strained in compression. As the overgrowth thickens, the strain decreases rapidly so that very little remains after 3 monoatomic layers have formed. The Auger line profile from a strained Pd monolayer in intimate contact with a Cu substrate is different from what one gets from bulk Pd suggesting that a line profile analysis of the AES spectra from monolayer epitaxial films may be useful in determining the modified electronic structure resulting from the Pd/Cu interaction. The results obtained so far were carried out with a UHV-RHEED system built 12 years ago. Because of the almost continuous useage of this system on the Pd/Cu studies, little time was available for studying other potentially usefuel systems, such as those involving Pt. The recent availability of a LEED instrument, a new and more flexible stainless steel UHV system, was constructed. This system is almost finished. It will allow the simultaneous investigation of two catalytic systems, given much needed flexibility

    EELS and AES study of epitaxially grown Pd(111) thin films

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