Band gap engineering in AA-stacked bilayer graphene

TL;DR

This paper explores how encapsulating AA-stacked bilayer graphene with dielectrics can induce an energy gap through an interlayer mass term, affecting electron transport and tunneling phenomena.

Contribution

It introduces a method to engineer a band gap in AA-stacked bilayer graphene via dielectric encapsulation and analyzes the resulting transport properties using a four-band continuum model.

Findings

Energy gap can be induced in AA-BLG by dielectric encapsulation.

Interlayer mass-term difference couples Dirac cones and affects transport.

Klein tunneling is suppressed, replaced by Fabry-Pérot resonances.

Abstract

We demonstrate that AA-stacked bilayer graphene (AA-BLG) encapsulated by dielectric materials can possess an energy gap due to the induced mass term. Using the four-band continuum model, we evaluate transmission and reflection probabilities along with the respective conductance. Considering interlayer mass-term difference opens a gap in the energy spectrum and also couples the two Dirac cones. This cone coupling induces an inter-cone transport that is asymmetric with respect to the normal incidence in the presence of asymmetric mass-term. The energy spectrum of the gapped AA-BLG exhibits electron-hole asymmetry that is reflected in the associated intra- and inter-cone channels. We also find that even though Klein tunneling exists in gated and biased AA-BLG, it is precluded by the interlayer mass-term difference and instead Febry-P\'erot resonances appear.