Abstract
We explore the adsorption of on a range of metal substrates by means of first-principles density functional theory calculations. Including van der Waals forces in the density functional is essential to capture the interaction between and a metal surface, and obtain reliable interface potential steps and Schottky barriers. Special care is taken to construct interface structures that have a mismatch between the and the metal lattices of . is chemisorbed on the early transition metal Ti, which leads to a strong perturbation of its (electronic) structure and a pinning of the Fermi level 0.54 eV below the conduction band due to interface states. is physisorbed on Au, where the bonding hardly perturbs the electronic structure. The bonding of on other metals lies between these two extreme cases, with interface interactions for the late transition metals Co, Ni, Cu and the simple metal Mg that are somewhat stronger than for the late transition metals Pd, Ag, Pt and the simple metal Al. Even a weak interaction, such as in the case of Al, gives interface states, however, with energies inside the band gap, which pin the Fermi level below the conduction band.
4 More- Received 23 October 2015
- Revised 13 January 2016
DOI:https://doi.org/10.1103/PhysRevB.93.085304
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