Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 17: Semiconductor Substrates
O 17.9: Vortrag
Montag, 31. März 2014, 18:00–18:15, PHY C 213
Ultra-thin ZnO on Metal Substrates as ZnO Surface Model — •Bjoern Bieniek, Oliver T. Hofmann, Patrick Rinke, and Matthias Scheffler — Fritz Haber Institut der MPG, 14195 Berlin
In the context of catalysis and hybrid inorganic/organic systems, metal supported ultra-thin ZnO can be used as model systems. However, it is not clear to what degree the ZnO films resemble the surfaces of ZnO or whether they exibit significantly different properties. We investigate the structure of ultra-thin ZnO films (1 to 4 layers) on the (111) surfaces of Ag, Cu, Pd, and Pt by means of density-functional theory. The free-standing ZnO monolayer adopts an α-BN structure. This structure prevails on the metal substrates, and we obtain coincidence structures in good agreement with experiment [1, 2, 3]. Thicker ZnO layers adopt a wurtzite structure. The films exhibit a large random corrugation, which can be regularized by hydrogen adsorption. A hydrogen overlayer with 50% coverage is formed at chemical potentials that range from low vacuum to ultra-high vacuum H2 pressures. For the Ag substrate both α-BN and wurtzite ZnO films are accessible in this pressure range, while for Cu wurtzite films are favoured. The surface structure and the density of states of these hydrogen passivated ZnO thin films agree well with those of the bulk ZnO(0001)-2x1-H surface. [1] C. Tusche et al. PRL 99, 026102 (2007) [2] Y. Martynova et al., J. Cat., 301, 227-223 (2013) [3] G. Weirum et al. J. Phys. Chem. C, 114 (2010)