Structural and electronic properties of a large-scale Moiré pattern of hexagonal boron nitride on Cu(111) studied with density functional theory

Ralph Koitz,Marcella Iannuzzi,Ari P Seitsonen,Jürg Hutter

doi:10.1039/c3nr00709j

Abstract

Hexagonal boron nitride (h-BN) adsorbed on metal surfaces shows great promise for applications in nanoscience. Depending on the nature of the substrate, effects such as an extended corrugation of the monolayer can be observed and utilized, e.g. for the patterning of adsorbed molecules. Here we present an in-depth computational study of the structural and electronic properties of a 6 nm Moiré pattern formed by a rotated layer of h-BN on a Cu(111) surface. In contrast to related systems, the h-BN layer undergoes only minute structural changes upon adsorption. Nevertheless, the projected density of states at various atoms in the cell and the electrostatic potential above the surface are periodically modulated, leading to the experimentally observed electronic corrugation. We rationalize this observation with the variation in adsorption registry resulting in periodic changes of the lateral, rather than vertical, h-BN-Cu distances.

Highlights

Two-dimensional molecular sheets adsorbed on metallic substrates have received a lot of attention in recent years.[1]
We de ne the interaction energy Eint according to eqn (1), where Em opt refers to the total energy of the relaxed Moire system, while EBN and ECu are the total energies of the monolayer and metal, respectively, with atomic coordinates equal to those in the optimized full system
The experimentally observed electrostatic corrugation can originate without signi cant structural changes. It is the lateral rather than the vertical distance which is responsible for the shi of the Projected Density of States (PDOS) features, as it is much more strongly modulated along the cell diagonal

Summary

Introduction

Two-dimensional molecular sheets adsorbed on metallic substrates have received a lot of attention in recent years.[1] Such materials have shown promise for applications in nanoscience, for nanoelectronics,[2] chemical sensing,[3] and as template surfaces for molecular assembly.[4,5] Frequently graphene adsorbed on metals is studied in this context, but its isoelectronic analog hexagonal boron nitride (h-BN) exhibits interesting and versatile properties Both the lattice mismatch between h-BN and the substrate surface and the interaction strength have a strong in uence on the structural and electronic properties of the adsorption system. In addition to the mismatch of lattice constants, a rotation of the layers relative to each other

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Conclusion