Search

The formation of a Schottky barrier at the interface between a metal and hexagonal boron nitride (h-BN) is studied using density functional theory. For metals whose work functions range from 4.2 to 6.0 eV, we find Schottky barrier heights for holes between 1.2 and 2.3 eV. A central role in determining the Schottky barrier height is played by a potential step of between 0.4 and 1.8 eV that is formed at the metal∣/i-BN interface and effectively lowers the metal work function. If h-BN is physisorbed, as is the case on fee Cu, Al, Au, Ag, and Pt(111) substrates, the interface potential step is described well by a universal function that depends only on the distance separating h-BN from the metal surface. The interface potential step is largest when h-BN is chemisorbed, which is the case for hep Co and Ti (0001) and for fee Ni and Pd (111) substrates. [ABSTRACT FROM AUTHOR]

Devising ways of opening a band gap in graphene to make charge-carrier masses finite is essential for many applications. Recent experiments with graphene on hexagonal boron nitride (h-BN) offer tantalizing hints that the weak interaction with the substrate is sufficient to open a gap, in contradiction of earlier findings. Using many-body perturbation theory, we find that the small observed gap is what remains after a much larger underlying quasiparticle gap is suppressed by incommensurability. The sensitivity of this suppression to a small modulation of the distance separating graphene from the substrate suggests ways of exposing the larger underlying gap. [ABSTRACT FROM AUTHOR]