Ultra-thin metal overlayers on Cu(001)
Understanding metal overlayers on metal substrates is important both scientifically and technologically. In this thesis, the author has investigated ultra-thin metal films on a Cu(001) surface using Atom Beam Scattering (ABS), Low Energy Diffraction (LEED) and Auger Electron Spectroscopy (AES). The growth of Hg and Pb overlayers has been studied in real time by using ABS. Changes in the growth mode are shown to be dependent on substrate temperature; while lead shows a self-similar growth within the submonolayer region. Growth of Pb island size is well characterized by a power law. ABS diffraction has given us information on the structure of overlayers. The Hg/Cu(001) system displays a richness in overlayer phases. Four ordered first monolayer phases and two second layer phases have been obtained, and corresponding structure models have been proposed. A detailed study of Pb overlayers grown on Cu(001) at low temperature has been carried out for the first time. Two Pb ordered phases were obtained. They are high order commensurate phases with symmetries (5 [times] 5)Rtan[sup [minus]1] (3/4) and ([radical]61 [times] [radical]61)Rtan[sup [minus]1] (5/6), respectively. Utilizing the top layer sensitivity of ABS, it was found that overlayers are buckled in most cases; buckling is mainly caused by the arrangement of atoms in the supercell of the overall structures. A novel phenomenon that occurs upon adsorbing low coverage Pb or Bi on Cu(001) is reported. Upon Pb or Bi adsorption, the Cu(001) surface corrugation is enhanced more than ten times than that of the clean Cu(001). Meantime adsorption of Hg atoms is found to have no effect on Cu(001). Computer simulations for a one-dimensional model have been carried out to analyze this phenomenon. Disordering of Pb overlayers upon increasing the sample temperature was also investigated. A first order to disorder phase transition has been found while heating the c(5[radical]2 [times] [radical]2) overlayer.
- Research Organization:
- Syracuse Univ., NY (United States)
- OSTI ID:
- 6987625
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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BISMUTH
STRUCTURAL CHEMICAL ANALYSIS
SURFACE PROPERTIES
COPPER
COATINGS
LEAD
MERCURY
AUGER ELECTRON SPECTROSCOPY
ELECTRON DIFFRACTION
EPITAXY
THIN FILMS
COHERENT SCATTERING
DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
FILMS
METALS
SCATTERING
SPECTROSCOPY
TRANSITION ELEMENTS
360102* - Metals & Alloys- Structure & Phase Studies