The growth morphology of ultrathin (up to 5 ML) vanadium oxide films on TiO2(1 1 0) has been investigated by scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). It has been found that the reactive evaporation technique produces more uniform and better-ordered vanadia layers than the post-oxidation method. At low coverages V-oxide clusters adsorb on top of the fivefold-coordinated Ti rows of the substrate. With increasing coverage the clusters agglomerate and form strands, which are oriented along the [0 0 1] titania direction. For oxide coverage >2 ML the strands cover uniformly the titania substrate, forming a texture along the [0 0 1] direction, and give rise to a (1 · 1) LEED pattern. The latter is consistent with the growth of an epitaxial rutile-type VO2 phase.
The growth of ultrathin films of vanadium oxide on TiO2(110)
AGNOLI, STEFANO;SAMBI, MAURO;GRANOZZI, GAETANO;
2004
Abstract
The growth morphology of ultrathin (up to 5 ML) vanadium oxide films on TiO2(1 1 0) has been investigated by scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). It has been found that the reactive evaporation technique produces more uniform and better-ordered vanadia layers than the post-oxidation method. At low coverages V-oxide clusters adsorb on top of the fivefold-coordinated Ti rows of the substrate. With increasing coverage the clusters agglomerate and form strands, which are oriented along the [0 0 1] titania direction. For oxide coverage >2 ML the strands cover uniformly the titania substrate, forming a texture along the [0 0 1] direction, and give rise to a (1 · 1) LEED pattern. The latter is consistent with the growth of an epitaxial rutile-type VO2 phase.
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