Bias Free Gap Creation in Bilayer Graphene

TL;DR

This paper proposes a novel method to create significant electronic band gaps in bilayer graphene without external electric fields, using electron-phonon interactions with ionic materials, potentially simplifying graphene-based electronics.

Contribution

It introduces a new approach to induce large band gaps in bilayer graphene via electron-phonon coupling with ionic materials, avoiding external electric fields.

Findings

Large band gaps can be achieved at intermediate electron-phonon coupling.

The gap results from amplified Coulomb interactions due to interlayer proximity.

Method bypasses limitations of existing gap creation techniques.

Abstract

For graphene to be utilized in the digital electronics industry the challenge is to create bandgaps of order 1eV as simply as possible. The most successful methods for the creation of gaps in graphene are (a) confining the electrons in nanoribbons, which is technically difficult or (b) placing a potential difference across bilayer graphene, which is limited to gaps of around 300meV for reasonably sized electric fields. Here we propose that electronic band gaps can be created without applying an external electric field, by using the electron-phonon interaction formed when bilayer graphene is sandwiched between highly polarisable ionic materials. We derive and solve self-consistent equations, finding that a large gap can be formed for intermediate electron-phonon coupling. The gap originates from the amplification of an intrinsic Coulomb interaction due to the proximity of carbon atoms in neighbouring planes.