Adhesion and electronic structure of graphene on hexagonal boron nitride substrates

TL;DR

This paper uses first-principles calculations to study how graphene adheres to h-BN substrates, revealing the role of van der Waals forces, stacking configurations, and substrate-induced electronic effects, aligning with recent experimental observations.

Contribution

It provides detailed insights into the adhesion energies, electronic structure modifications, and moiré pattern effects of graphene on h-BN, highlighting the importance of stacking and long-range interactions.

Findings

Adhesion is dominated by van der Waals forces.

Stacking configurations induce substrate-dependent mass terms.

Moiré structures have significantly smaller band gaps than local mass terms.

Abstract

We investigate the adsorption of graphene sheets on h-BN substrates by means of first-principles calculations in the framework of adiabatic connection fluctuation-dissipation theory in the random phase approximation. We obtain adhesion energies for different crystallographic stacking configurations and show that the interlayer bonding is due to long-range van der Waals forces. The interplay of elastic and adhesion energies is shown to lead to stacking disorder and moir\'e structures. Band structure calculations reveal substrate induced mass terms in graphene which change their sign with the stacking configuration. The dispersion, absolute band gaps and the real space shape of the low energy electronic states in the moir\'e structures are discussed. We find that the absolute band gaps in the moir\'e structures are at least an order of magnitude smaller than the maximum local values of the mass term. Our results are in agreement with recent STM experiments.