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

Paper SS1-WeM11
Reconstructed Oxide Structures Stable in Air: Monolayer Silicate on Hexagonal SiC Surfaces

Wednesday, November 4, 1998, 11:40 am, Room 308

Session: Physics of Semiconductors
Presenter: U. Starke, University of Erlangen-Nuernberg, Germany
Authors: U. Starke, University of Erlangen-Nuernberg, Germany
J. Schardt, University of Erlangen-Nuernberg, Germany
J. Bernhardt, University of Erlangen-Nuernberg, Germany
K. Heinz, University of Erlangen-Nuernberg, Germany
Correspondent: Click to Email
Ultrathin oxide layers on hexagonal SiC surfaces were studied using low-energy electron diffraction (LEED) and Auger electron spectroscopy (AES). SiC(0001) and SiC(000-1) samples were ex situ prepared using thermal hydrogen etching or microwave powered hydrogen plasma treatment. A well ordered (@sr@3x@sr@3)R30° reconstructed surface is observed by LEED immediately upon introduction into vacuum. The samples contain oxygen of approximately one layer equivalent bonded to Si atoms as indicated by AES. By a full dynamical LEED structure analysis carried out for the SiC(000-1) surface the crystallographic structure is determined: The silicon oxide is arranged as a silicate (Si@sub 2@O@sub 3@) layer ontop of the SiC substrate forming rings of the (@sr@3x@sr@3)R30° periodicity with twofold coordinated oxygen atoms in the topmost position. The oxygen incorporation into the surface is presumably caused by a rapid oxidation in air of the well ordered topmost substrate bilayer. The extreme stability of the resulting surface reconstruction is caused by the absence of dangling bonds in the surface terminating silicate layer. Similar results are indicated for the SiC(0001) surface by preliminary LEED calculations.