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Growth Morphology and Electronic Structure of Ultra-Thin TaOx Films on Ag(100)

Published online by Cambridge University Press:  10 February 2011

M. M. Howard
Affiliation:
Department of Physics, University of New Orleans, New Orleans, LA 70148
C. A. Ventrice Jr
Affiliation:
Department of Physics, University of New Orleans, New Orleans, LA 70148
H. Geisler
Affiliation:
Department of Chemistry, Xavier University, New Orleans, LA 70125
D. A. Hite
Affiliation:
CAMD/Department of Physics, Louisiana State University, Baton Rouge, LA 70806
P. T. Sprunger
Affiliation:
CAMD/Department of Physics, Louisiana State University, Baton Rouge, LA 70806
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Abstract

A study of the growth morphology and electronic structure of TaOx films on the Ag(100) substrate has been performed to determine the properties of ultra-thin TaOx films without the influence of a mixed interfacial oxide (i.e., a disordered SiO2/TaOx interface for growth on Si). The TaO, films were grown by thermal evaporation of Ta in an oxygen atmosphere of 1 × 101−6 Torr. Growth on a Ag(100) surface held at room temperature results in an amorphous TaOx overlayer, as determined by low energy electron diffraction. The onset of ordering of these films occurs for a post-anneal at ∼500°C. A diffraction pattern that corresponds to a multi-domain overlayer structure is observed for anneals at ∼550°C. Deposition of Ta without oxygen results in the formation of Ta islands. These results indicate that there is a very weak adsorbatesubstrate interaction. Photoemission measurements of the TaOx films show the formation of a band gap with the valence band maximum residing at 3.5 eV below the Fermi level. Core level shifts of ∼3.5 eV are observed for the Ta with no indication of metallic Ta at the surface.

Type
Research Article
Copyright
Copyright © Materials Research Society 2000

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