Versatile sputtering technology for Al2O3 gate insulators on graphene

TL;DR

This paper introduces a versatile sputtering method for fabricating high-quality Al2O3 gate insulators on graphene, achieving comparable electrical performance to traditional methods and enabling improved device fabrication.

Contribution

A novel sputtering-based fabrication process for Al2O3 gate insulators on graphene with performance comparable to atomic layer deposition.

Findings

Al2O3 layers have high dielectric constant (~8)

Low hysteresis and high breakdown voltage achieved

Moderate carrier mobility in graphene devices

Abstract

We report a novel fabrication method of graphene Al2O3 gate insulators based on sputtering. Electrical performance of dual-gated mono- and bilayer exfoliated graphene devices is presented. Sputtered Al2O3 layers possess comparable quality to oxides obtained by atomic layer deposition (ALD) with respect to a high relative dielectric constant of about 8, as well as low-hysteresis performance and high breakdown voltage. We observe a moderate carrier mobility of about 1000 cm2/Vs in graphene and 350 cm2/Vs in its bilayer due to increased resonant scattering on atomic scale defects. Most likely this originated from the thin Al precursor layer evaporated prior to sputtering the Al2O3 gate oxide.