Plasmons in electrostatically doped graphene

TL;DR

This paper investigates how inhomogeneous electrostatic doping affects plasmon properties in graphene, revealing differences from uniform doping and providing insights for realistic device applications.

Contribution

It analyzes plasmon behavior in realistically doped graphene configurations, contrasting with idealized uniform doping assumptions.

Findings

Plasmons in backgated ribbons resemble uniformly doped cases with scaled Fermi energy.

Ribbon pairs at opposite potentials show similar plasmon properties to uniform doping.

Uniform electric field exposure leads to distinct plasmon dispersion and spatial profiles.

Abstract

Graphene has raised high expectations as a low-loss plasmonic material in which the plasmon properties can be controlled via electrostatic doping. Here, we analyze realistic configurations, which produce inhomogeneous doping, in contrast to what has been so far assumed in the study of plasmons in nanostructured graphene. Specifically, we investigate backgated ribbons, co-planar ribbon pairs placed at opposite potentials, and individual ribbons subject to a uniform electric field. Plasmons in backgated ribbons and ribbon pairs are similar to those of uniformly doped ribbons, provided the Fermi energy is appropriately scaled to compensate for finite-size effects such as the divergence of the carrier density at the edges. In contrast, the plasmons of a ribbon exposed to a uniform field exhibit distinct dispersion and spatial profiles that considerably differ from uniformly doped ribbons. Our results provide a road map to understand graphene plasmons under realistic electrostatic doping conditions.