Effects of metallic contacts on electron transport through graphene

TL;DR

This study uses first-principles calculations to analyze how metallic aluminum contacts influence electron transport in graphene, revealing charge transfer effects, conductance asymmetry, and potential profiles relevant for device modeling.

Contribution

It provides detailed first-principles insights into the conductance behavior of graphene with metallic contacts, including potential profiles and conductance minima.

Findings

Charge transfer causes electron-hole asymmetry.

Long junctions show conductance minima at Dirac points.

Parameters for effective models are derived.

Abstract

We report on a first-principles study of the conductance through graphene suspended between Al contacts as a function of junction length, width, and orientation. The charge transfer at the leads and into the freestanding section gives rise to an electron-hole asymmetry in the conductance and in sufficiently long junctions induces two conductance minima at the energies of the Dirac points for suspended and clamped regions, respectively. We obtain the potential profile along a junction caused by doping and provide parameters for effective model calculations of the junction conductance with weakly interacting metallic leads.