First-principle investigation of the electronic structure and optical properties of graphene/boron nitride lateral heterostructures

TL;DR

This study uses ab initio and tight-binding methods to analyze the electronic and optical properties of graphene/boron nitride heterostructures, revealing family-specific features and new insights into their optical behavior.

Contribution

It demonstrates that the classification of heterostructures by gapwidth extends to other electronic states and links electronic structure to optical properties using combined theoretical approaches.

Findings

Classification by gapwidth applies to electronic states near the gap

Optical absorption spectra show family-specific peak energies and intensities

Tight-binding model explains charge redistribution and optical selection rules

Abstract

We investigate the electronic and optical properties of lateral heterostructures made of alternated armchair ribbons of graphene and hexagonal boron nitride. It is known that the gapwidth of these heterostructures can be classified into three families depending on the width of the graphene part. Here, by employing ab initio methods (standard and time-dependent density functional theory and GW), we demonstrate that such classification still holds for other electronic states close to the gap. We show that they display trends substantially different from those known for the gapwidth and originate family-specific features in the screening properties and optical absorption spectra (peak energy and intensity). In addition, our use of a tight binding model originally introduced for isolated nanoribbons allows us to discuss some crucial heterostructure's properties in view of those of its isolated building blocks, including charge redistribution at the edges, gap hierarchy inversion, and specific optical selection rules. By bridging the electronic structure to optical absorption spectra in a comprehensive set of systems, this study sets the stage for more refined investigations on the absorption properties of graphene/boron nitride lateral heterostructures.