Ultra Low Specific Contact Resistivity in Metal-Graphene Junctions via Atomic Orbital Engineering

TL;DR

This paper demonstrates a method to significantly reduce contact resistivity in graphene devices by patterning contacts and electrostatic doping, supported by multi-scale modeling, offering practical guidelines for contact engineering in 2D materials.

Contribution

It introduces a systematic approach combining patterning and doping to achieve ultra low contact resistivity in graphene, validated by experimental and theoretical analysis.

Findings

67% increase in current injection with edge contacts

Reduced contact resistivity from 1372 to 456 {a}a}m with patterning

Further decrease to 45 {a}a}m via electrostatic doping

Abstract

A systematic investigation of graphene edge contacts is provided. Intentionally patterning monolayer graphene at the contact region creates well-defined edge contacts that lead to a 67% enhancement in current injection from a gold contact. Specific contact resistivity is reduced from 1372 {\Omega}m for a device with surface contacts to 456 {\Omega}m when contacts are patterned with holes. Electrostatic doping of the graphene further reduces contact resistivity from 519 {\Omega}m to 45 {\Omega}m, a substantial decrease of 91%. The experimental results are supported and understood via a multi-scale numerical model, based on density-functional-theory calculations and transport simulations. The data is analyzed with regards to the edge perimeter and hole-to-graphene ratio, which provides insights into optimized contact geometries. The current work thus indicates a reliable and reproducible approach for fabricating low resistance contacts in graphene devices. We provide a simple guideline for contact design that can be exploited to guide graphene and 2D material contact engineering.