Influence of oxygen on surface reconstruction and growth of (0 0 1) vanadium

In this paper, the role of oxygen on surface reconstruction and growth of (0 0 1) vanadium is investigated. By using electron diffraction, in-plane lattice spacing oscillations are observed during the layer by layer vanadium growth. The amplitude of these oscillations which are due to elastic relaxation at the edges of the two-dimensional (2D) growing islands, are sometimes very large and thus cannot be explained by size effect in homo-epitaxy. We observe that the oscillation amplitude is clearly correlated with the presence of oxygen on the initial surface, as checked by Auger spectroscopy. As the presence of oxygen induces surface reconstructions, the electron diffraction experiments also allow us to demonstrate that these superstructures are compressed compared to an oxygen free 1×1 V surface. The peculiar morphology of these surface reconstructions, investigated by scanning tunnelling microscopy, may be explained by this compressive strain.