AVS 53rd International Symposium
    Surface Science Wednesday Sessions
       Session SS1-WeA

Paper SS1-WeA5
LEEM Observations of Pb Growth on W(110)

Wednesday, November 15, 2006, 3:20 pm, Room 2002

Session: Growth Processes on Metal and Semiconductor Surfaces
Presenter: S. Chiang, University of California, Davis
Authors: D.B. Hoffman, University of California, Davis
S. Chiang, University of California, Davis
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Although surface energy considerations would suggest that Pb would grow layer-by-layer on W(110), an earlier study,@footnote 1@ using low energy electron diffraction (LEED), Auger spectroscopy, and thermal desorption spectroscopy, found Stranski-Krastanov growth. After the completion of the first monolayer, our low energy electron microscope (LEEM) observations of this system show the development of 3D Pb crystallites. For Pb deposition at substrate temperature of 200C, the islands grow together and form larger islands with quasi-hexagonal sides. After about 8ML growth, gradually raising the temperature to 325C, the Pb meltiing point, causes the crystals to melt. As they melt, the islands suddenly move to step bunches and become round. They also become smaller as the Pb desorbs from the surface. Finally, some round black islands remain, corresponding to a quasi-(4x1) LEED pattern. If the temperature is lowered below 325C, those remaining islands develop a hexagonal shape. At 425C, these desorb from the surface. For growth at 300C, there appears to be a maximum coverage, possibly resulting from the competition between Pb condensation from the vapor and desorption due to the temperature. The few observed islands typically grow on top of high density step bunches. The density of the crystallites depends on the substrate temperature. For growth at 200C, the island density is about 40 times higher than for growth at 300C, with only 3 islands apparent in a 10µm field of view at the higher temperature. @FootnoteText@ @footnote 1@ E. Bauer, H. Poppa, G. Todd, Thin Solid Films, 28, 19 (1975).