Optical Absorption Spectra of Electrically Gated Bilayer Graphene

TL;DR

This study uses first-principles methods to analyze how electric gating affects the electronic structure and optical absorption of bilayer graphene, revealing dependencies on electric field, stacking, and light polarization.

Contribution

It provides detailed first-principles calculations of the band gap and optical spectra of gated bilayer graphene, including effects of stacking and polarization, and discusses many-electron effects.

Findings

Induced band gap agrees with experiments for electric fields below 1.5 V/nm.

Infrared absorbance depends on stacking and polarization.

Many-electron effects influence optical response.

Abstract

The electronic structure and optical response of electrically gated bilayer graphene are studied by first-principles approaches. We have obtained the induced band gap that is in good agreement with experiment when the applied electric field is less than 1.5 V/nm. The infrared optical absorbance is calculated within the single-particle excitation picture and its fine structures are presented. In addition, the calculated infrared optical absorbance is found to be strongly depending on stacking styles of bilayer graphene and the polarization direction of the incident light, which provides efficient ways to identify the electric-field intensity and stacking styles in experiment. Finally, many-electron effects are discussed.