AVS 49th International Symposium
    Surface Science Monday Sessions
       Session SS2-MoM

Paper SS2-MoM11
The Polar O-ZnO(000-1) Surface: Stability and Interaction with Hydrogen

Monday, November 4, 2002, 11:40 am, Room C-112C

Session: Oxide Structure and Surface Chemistry
Presenter: M. Kunat, Ruhr-University Bochum, Germany
Authors: M. Kunat, Ruhr-University Bochum, Germany
St. Gil Girol, Ruhr-University Bochum, Germany
U. Burghaus, Ruhr-University Bochum, Germany
Ch. Wöll, Ruhr-University Bochum, Germany
Correspondent: Click to Email
The question about the stability of the polar surfaces of zinc oxide has been the topic of many experimental and theoretical investigations. Here we report on an investigation using the highly surface sensitive method of He-atom scattering (HAS). The clean, H-free surface shows (1x3) superlattice spots in He-atom diffraction scans. This finding is in contrast to previous work@footnote 1@ where the presence of a (1x1) overlayer was found, but is in agreement with Taskers rule,@footnote 2@ which predicts instabilities for polar oxide surfaces. After optimizing the preparation conditions for the O-ZnO(000-1) surface, in particular by employing annealing in an oxygen atmosphere, we were able to observe weak (1x3) spots not only with HAS but also in low energy electron diffraction (LEED). Exposure to hydrogen atoms leads to the disappearance of the (1x3) overlayer spots and the formation of a well-defined (1x1) diffraction pattern in both HAS and LEED, similar to the case of the Zn-ZnO(0001) surface previously studied in our laboratory.@footnote 3@ The formation of the H-atom overlayer is accompanied by a shoulder in the O1s XPS data, indicating the formation of OH-species. In addition first results of sticking coefficients of carbon monoxide as a function of hydrogen preexposure will be discussed. @FootnoteText@ @footnote 1@ A. Wander, F. Schedin, P. Steadman, A. Norris, R. MCGrath, T.S. Turner, G. Thornton, and N.M. Harrison, Phys. Rev. Lett. 86 (2001) 3811.@footnote 2@ P.W. Tasker, J. Phys. C: Solid State Phys. 12 (1979) 4977.@footnote 3@ Th. Becker, St. Hövel, M. Kunat, Ch. Boas, U. Burghaus, and Ch. Wöll, Surf. Sci. 486 (2001) L502.