Nonlinear screening and charge redistribution in periodically doped graphene

TL;DR

This paper develops a numerical theory for nonlinear screening and charge redistribution in periodically doped graphene, revealing how long-range Coulomb interactions influence electron potential and concentration in 2D heterostructures.

Contribution

It introduces a computationally efficient method to solve the nonlinear screening problem in periodically doped graphene considering all long-range effects.

Findings

Power law distance screening in 2D systems differs from exponential screening in 3D.

Electron inflow from high- to low-doped regions depends on doping levels.

The method applies broadly to doped 2D heterostructures with linear energy spectra.

Abstract

The screening problem for the Coulomb potential of a charge located in a two-dimensional (2D) system has an intriguing solution with a power law distance screening factor due to out-of-plane electrical fields. This is crucially different from a three-dimensional case with exponential screening. The long-range action of electric fields results in the effective inflow of electrons from high-doped regions to low-doped regions of a 2D heterostructure. In graphene and other materials with linear energy spectrum for electrons, such inflow in low-doped regions also occurs, but its effectiveness is dependent on doping level. This can be used for fabricating high-mobility conducting channels. We provide the theory for determining electron potential and concentration in a periodically doped graphene sheet along one dimension taking into account all effects of long-range 2D screening. This results in a substantially nonlinear integro-differential problem, which is solved numerically via computationally cheap algorithm. Similar nonlinear problems arise in a wide range of doped 2D heterostructures made of linear spectrum materials.