IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Tuesday Sessions
       Session SS1-TuM

Paper SS1-TuM1
Microstructure of the Al@sub 2@O@sub 3@(11-20) Surface and Ultrathin Nb Films

Tuesday, October 30, 2001, 8:20 am, Room 121

Session: Adsorption on Oxide Surfaces
Presenter: G. Witte, Ruhr-Universität Bochum, Germany
Authors: G. Witte, Ruhr-Universität Bochum, Germany
Th. Becker, Ruhr-Universität Bochum, Germany
A. Birkner, Ruhr-Universität Bochum, Germany
Ch. Woöll, Ruhr-Universität Bochum, Germany
Correspondent: Click to Email
Despite the technological importance of sapphire such as a support for devices or catalysts the microstructure of its surfaces have yet not been investigated in great detail. Here we report on a combined AFM, LEED, HAS and XPS study of the microstructure of the Al@sub 2@O@sub 3@(11-20) surface and the initial growth of ultrathin (110) oriented Nb-films. The samples were first heated in air which leads to atomically flat but carbon coated surfaces as indicated by the AFM and XPS measurements and requires a further preparation by sputtering and annealing to produce clean and well ordered surfaces. The resulting surface structure was found to depend sensitively on the annealing temperature. Heating above 1300K causes a substantial oxygen reduction at the surface which is accompanied by a long ranging highly periodic surface reconstruction without facetting. The subsequent growth of ultrathin Nb-films reveals the well known epitaxial relation between Nb and sapphire but also indicates that the films are not continuos. Instead flat islands are formed in a growth mode similar to that obtained for Ni on diamond.@footnote 1@ @FootnoteText@ @footnote 1@J.Braun, J.P.Toennies and Ch.Wöll, Phys. Rev. B60, 11707 (1999).