Electronic structure of folded hexagonal boron nitride

TL;DR

This study uses density functional theory to analyze how folding in hexagonal boron nitride alters its electronic properties, revealing stacking-dependent band gap variations and a type-II junction formation.

Contribution

It provides the first detailed theoretical analysis of the electronic effects of folding in h-BN, highlighting stacking configurations and their impact on band structure.

Findings

Folded regions cause significant band gap variations.

Stacking configurations depend on fold orientation.

Folded monolayers form type-II junctions.

Abstract

Folded regions are commonly encountered in a number of hexagonal boron nitride (h-BN) based bulk and nanostructured materials. Two types of structural modifications occur in folded h-BN layers: local curvature at the folded edges and interlayer shear of the layers which changes the stacking of the overlapping flat regions. In this work we discuss, via density functional theory simulations, the impact of these structural modifications on the ground state electronic structure of the pristine monolayer. We show that, depending on the fold orientation, the overlapping region might present different stacking configurations with subsequent variations of the fundamental band gap; further gap changes occur at the folded regions. The overall electronic structure of a BN folded monolayer can finally be described as a type-II junction between two wide gap semiconductors located at the curved and flat overlapping zones.