Tuning the Electronic Structure of Graphene by Controlling Spatial Confinement

TL;DR

This paper explores how stacking graphene nanoribbons with graphene layers can modify electronic properties, such as opening a band gap and tuning band steepness, which is promising for electronic device applications.

Contribution

It demonstrates how heterostructures of graphene nanoribbons and graphene layers can alter electronic structures, including gap opening and band tuning, using tight-binding models.

Findings

A local gap of ~0.6 eV can be induced in bilayer heterostructures.

The band steepness can be tuned by different stacking configurations.

Heterostructures exhibit electronic properties different from individual components.

Abstract

The electronic properties of a material depend on the spatial freedom of the electron wavefunction. A well-known example is graphite, which is a conventional gapless semiconductor, while a single layer of it, graphene, exhibits extremely high electronic conductivity. Nevertheless, graphene ribbons can have different physical properties, such as a tunable band gap, ranging from gapless to a large band gap semiconductor. The purpose of this study is to investigate the electronic structure of few-layer graphene composed of a layer of graphene nanoribbons and graphene sheet(s), where quasi-one-dimensional nanoribbons can interact with a two-dimensional sheet of graphite. Using the tight-binding model for graphite, we show how different configurations of such heterostructures can affect the electronic structure, which is different from that of their components. Our results show that systems composed of semiconducting AGNRs can not be seen as two separate systems. Namely, a local gap of ~0.6 eV at the Dirac point for dispersive bands can be opened in a bilayer configuration composed of a layer of gapless armchair nanoribbon stacked on graphene. We demonstrate that the band steepness in these structures can be tuned, highlighting their potential for electronic applications.