Electron transport in graphene/graphene side-contact junction by plane-wave multiple scattering method

TL;DR

This paper develops a plane-wave multiple scattering method to analyze electron transport in graphene side-contact junctions, enabling efficient calculations of tunneling currents influenced by stacking and geometric configurations.

Contribution

It introduces a novel plane-wave based scattering approach for side-contact graphene junctions, improving computational efficiency and flexibility over existing methods.

Findings

Transport properties depend on stacking order (AA or AB)

Tunneling current varies with vacuum gap size

Transport behavior explained by orbital hybridization and delocalization

Abstract

Electron transport in graphene is along the sheet but junction devices are often made by stacking different sheets together in a "side-contact" geometry which causes the current to flow perpendicular to the sheets within the device. Such geometry presents a challenge to first-principles transport methods. We solve this problem by implementing a plane-wave based multiple scattering theory for electron transport. This implementation improves the computational efficiency over the existing plane-wave transport code, scales better for parallelization over large number of nodes, and does not require the current direction to be along a lattice axis. As a first application, we calculate the tunneling current through a side-contact graphene junction formed by two separate graphene sheets with the edges overlapping each other. We find that transport properties of this junction depend strongly on the AA or AB stacking within the overlapping region as well as the vacuum gap between two graphene sheets. Such transport behaviors are explained in terms of carbon orbital orientation, hybridization, and delocalization as the geometry is varied.