Interface effects in hybrid hBN-graphene nanoribbons

Carlos Leon,Marcio Costa,Leonor Chico,Andrea Latgé

doi:10.1038/s41598-019-39763-5

Abstract

We analyze the electronic properties of a hybrid graphene-BN nanoribbon system, using a Hubbard model Hamiltonian within a mean field approximation. Due to the different electronegativities of the boron and nitrogen atoms, an electric field is induced across the zigzag graphene strip, breaking the spin degeneracy of the electronic band structure. Optimal tight-binding parameters are found from first-principles calculations. Edge potentials are proposed as corrections for the on-site energies, modeling the BN-graphene nanoribbon interfaces. We show that half-metallic responses in the hybrid systems may be driven with the help of an external electric field. We also study the role of defects across the graphene nanoribbon and at the h-BN/graphene interface regions. Modulations on the spin-dependent gaps may be achieved depending on the nature and position of the defect, constituting a way towards spin-gap engineering by means of spatial doping.

Highlights

Graphene is a zero-band-gap semiconductor with valence and conduction bands touching at the corners of the Brillouin zone
Insulator-metal transitions in BN nanoribbons have been predicted with the application of transversal electric fields[12]; the actual critical field depends on the width of the ribbon
When an electric field is applied in the transversal direction of zigzag graphene nanoribbons (ZGNRs), the system behaves as a half-metallic material[13,14]

Summary

Introduction

Graphene is a zero-band-gap semiconductor with valence and conduction bands touching at the corners of the Brillouin zone. Post-processing DFT calculations consider interactions between a large range of neighbor atoms, we are just interested in the on-site energy and first nearest-neighbor hoppings, so parameters www.nature.com/scientificreports Taking into account the important contribution from edge states to the electronic density of zigzag BN nanoribbons and the electronegativity difference between B and N atoms, Zheng et al proposed a TB model for a ZBNNR system with on-site energy corrections in the form of effective edge potentials[30].

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Conclusion