Atomistic deconstruction of current flow in graphene based hetero-junctions

TL;DR

This paper presents a numerical approach for atomistically modeling current flow in graphene heterojunctions using NEGF formalism, enabling detailed analysis of electron transport phenomena at experimental scales.

Contribution

It introduces a k-space based NEGF method with recursive Green's function algorithm for atomistic simulations of graphene devices, including boundary condition improvements.

Findings

Simulated current flow in graphene heterojunctions matches experimental conductance data.

Revealed detailed electron optics and pseudospin effects in graphene p-n junctions.

Demonstrated minimized edge reflection effects through exact boundary conditions.

Abstract

We describe the numerical modeling of current flow in graphene heterojunctions, within the Keldysh Landauer Non-equilibrium Green's function (NEGF) formalism. By implementing a $k$-space approach along the transverse modes, coupled with partial matrix inversion using the Recursive Green's function Algorithm (RGFA), we can simulate on an atomistic scale current flow across devices approaching experimental dimensions. We use the numerical platform to deconstruct current flow in graphene, compare with experimental results on conductance, conductivity and quantum Hall, and deconstruct the physics of electron `optics' and pseudospintronics in graphene $p-n$ junctions. We also demonstrate how to impose exact open boundary conditions along the edges to minimize spurious edge reflections.