First-principles study of van der Waals interactions and lattice mismatch at MoS2/metal interfaces

We explore the adsorption of MoS 2 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 MoS 2 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 MoS 2 and the metal lattices of <1% . MoS 2 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 MoS 2 conduction band due to interface states. MoS 2 is physisorbed on Au, where the bonding hardly perturbs the electronic structure. The bonding of MoS 2 on other metals lies between these two extreme cases, with interface interactions for the late 3d transition metals Co, Ni, Cu and the simple metal Mg that are somewhat stronger than for the late 4d/5d 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 MoS 2 band gap, which pin the Fermi level below the conduction band.