Bipolar electron waveguides in graphene

TL;DR

This paper demonstrates how bipolar electron waveguides in graphene can be used to create a controllable pseudo-band-gap, enabling potential terahertz applications through analytical modeling of electron localization.

Contribution

It introduces a novel approach to engineer pseudo-gaps in graphene using bipolar waveguides with narrow top-gates, expanding the control over electron dispersion in Dirac materials.

Findings

Bipolar waveguides induce a non-monotonous dispersion in graphene.

Electrostatically controllable pseudo-band-gap is achievable.

Strong terahertz transitions are associated with the pseudo-gap.

Abstract

We show analytically that the ability of Dirac materials to localize an electron in both a barrier and a well can be utilized to open a pseudo-gap in graphene's spectrum. By using narrow top-gates as guiding potentials, we demonstrate that graphene bipolar waveguides can create a non-monotonous one-dimensional dispersion along the electron waveguide, whose electrostatically controllable pseudo-band-gap is associated with strong terahertz transitions in a narrow frequency range.