AVS 45th International Symposium
    Surface Science Division Thursday Sessions
       Session SS2-ThA

Paper SS2-ThA7
Photoemission Study of Ultra-thin NiO(111) Films Grown on Au(111)

Thursday, November 5, 1998, 4:00 pm, Room 309

Session: Oxide Growth and Structure
Presenter: C.A. Ventrice, Jr., University of New Orleans
Authors: B.R. King, University of New Orleans
M. Howard, University of New Orleans
P.S. Robbert, University of New Orleans
H. Geisler, University of New Orleans
C.A. Ventrice, Jr., University of New Orleans
D.A. Hite, CAMD/Louisiana State University
P.T. Sprunger, CAMD/Louisiana State University
Correspondent: Click to Email
Only a few systems are known where the polar surface of an ionic metal-oxide crystal can be grown without the introduction of surface impurities. One example of a stable polar surface is the growth of NiO(111) on Au(111) by evaporation of Ni in an O@sub 2@ atmosphere at ~300 °C.@footnote 1@ STM analysis of this surface has shown that the NiO(111) surface consists of a p(2x2) array of four-atom tripods with several missing-atom point defects on the surface as well as regions of bare Au.@footnote 1@ Angle-resolved photoelectron spectroscopy and x-ray absorption measurements have been performed to better understand the growth morphology and the resulting electronic structure of this system. Significant changes in the Au-5d photoemission intensity features are observed after the growth or the NiO which indicates that the Au regions observed with STM result from segregation, not NiO three-dimensional island growth into the Au substrate. The photoemission results also show a 1 eV shift in the Ni-3d emission to lower binding energy when compared to previously published results for single-crystal NiO(100).@footnote 2@ Since Ni deficient NiO results in a p-type substrate, this shift and the observation of missing-atom point defects with STM provide evidence that the (111) surface is Ni terminated. Analysis of structural changes in the Ni coordination upon oxidation is currently being performed by comparison of x-ray absorption features of Ni/Au(111) and NiO(111)/Au(111) systems. @FootnoteText@ @footnote 1@C. A. Ventrice, Jr., et al., Phys. Rev. B 49, 5773 (1994). @footnote 2@S. Hüffner et al., Z. Phys. B 83, 185 (1991).