Unravelling the electrical properties of epitaxial Graphene nanoribbons

TL;DR

This study investigates how the electrical resistivity of epitaxial graphene nanoribbons varies with width, revealing edge effects, doping control, and the impact of passivation layers, with implications for nanoscale electronic devices.

Contribution

It provides a comprehensive experimental analysis of size-dependent resistivity in graphene nanoribbons and introduces a conduction model considering edge and confinement effects.

Findings

Resistivity increases more dramatically than in metallic nanowires due to edge and band-gap effects.

Charge Neutrality point polarity switches below 50 nm ribbon width.

Passivation layers significantly affect charge carrier mean free path.

Abstract

The size-dependent electrical resistivity of single-layer graphene ribbons has been studied experimentally for ribbon widths from 16 nm to 320 nm. The experimental findings are that the resistivity follows a more dramatic trend than that seen for metallic nanowires of similar dimensions, due to a combination of surface scattering from the edges, band-gap related effects and shifts in the Fermi level due to edge effects. We show that the Charge Neutrality point switches polarity below a ribbon width of around 50 nm, and that at this point, the thermal coefficient of resistance is a maximum. The majority doping type therefore can be controlled by altering ribbon width. We also demonstrate that an alumina passivation layer has a significant effect on the mean free path of the charge carriers within the graphene, which can be probed directly via measurements of the width-dependent resistivity. We propose a model for conduction that takes edge and confinement effects into account.