Atomic-scale model for the contact resistance of the nickel-graphene interface

TL;DR

This study uses first-principles calculations to analyze electron transport at the nickel-graphene interface, revealing that covalent bonding leads to a consistent contact resistance regardless of contact area, aligning with experimental data.

Contribution

It provides a detailed atomic-scale model of contact resistance for nickel-graphene interfaces, highlighting the role of covalent bonding and offering a generic framework for covalently bonded graphene.

Findings

Contact resistance is similar across different geometries.

Covalent bonding results in a minimum contact resistance twice the ideal quantum limit.

Results agree with recent experimental measurements.

Abstract

We perform first-principles calculations of electron transport across a nickel-graphene interface. Four different geometries are considered, where the contact area, graphene and nickel surface orientations and the passivation of the terminating graphene edge are varied. We find covalent bond formation between the graphene layer and the nickel surface, in agreement with other theoretical studies. We calculate the energy-dependent electron transmission for the four systems and find that the systems have very similar edge contact resistance, independent of the contact area between nickel and graphene, and in excellent agreement with recent experimental data. A simple model where graphene is bonded with a metal surface shows that the results are generic for covalently bonded graphene, and the minimum attainable edge contact resistance is twice the ideal edge quantum contact resistance of graphene.