The growth of epitaxial VN(1 1 1) nanolayer surfaces |
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Authors: | A Glaser MG Ramsey J Redinger FP Netzer |
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Institution: | a Institut für Physik, Oberflächen- und Grenzflächenphysik, Karl-Franzens Universität Graz, A-8010 Graz, Austria b Institut für Allgemeine Physik, Technische Universität Wien, A-1060 Wien, Austria c Institut für Physikalische Chemie, Universität Wien, A-1090 Wien, Austria |
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Abstract: | Ultrathin films of vanadium nitride (1-20 monolayers = nanolayers) with (1 1 1) orientation have been grown on a Pt(1 1 1) surface by reactive evaporation of vanadium in NH3 atmosphere. The VN(1 1 1) surfaces have been investigated by X-ray and UV photoelectron spectroscopy, LEED, work function measurements, and ab initio DFT calculations. Nearly stoichiometric, well-ordered VN0.9 overlayers with their (1 × 1) unit cells rotationally aligned to the high symmetry directions of the Pt substrate have been obtained after annealing the films deposited at 300-500 °C in vacuum. The experimental valence band spectra have been compared to the theoretical density of states for differently terminated VN(1 1 1) surfaces, i.e. V and N terminated surfaces, bare and with chemisorbed hydrogen. The comparison suggests that the VN(1 1 1) nanolayers are terminated by a hexagonal layer of vanadium atoms, possibly covered with some chemisorbed hydrogen (which may originate from the preparation procedure). The VN nanolayer growth on Pt(1 1 1) follows a Stranski-Krastanov layer-plus-island growth mode. |
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Keywords: | Vanadium nitride Photoelectron spectroscopy Density functional theory |
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