Growth of large area graphene from sputtered films

TL;DR

This paper demonstrates a scalable method for producing large-area polycrystalline graphene via sputtered films and rapid thermal processing, highlighting the importance of cooling rate and layer configuration for quality and coverage.

Contribution

It introduces a novel, industrially scalable sputtering-based process for growing high-quality large-area graphene suitable for semiconductor integration.

Findings

Graphene grows on the top surface of the stack in contact with Ni or Ni-silicide.

Optimized rapid cooling is crucial for monolayer graphene formation.

Achieved up to 40% surface coverage with high-quality monolayer graphene.

Abstract

Techniques for mass-production of large area graphene using an industrial scale thin film deposition tool could be the key to the practical realization of a wide range of technological applications of this material. Here, we demonstrate the growth of large area polycrystalline graphene from sputtered films (a carbon-containing layer and a metallic layer) using in-situ or ex-situ rapid thermal processing in the temperature range from 650 to 1000 oC. It was found that graphene always grows on the top surface of the stack, in close contact with the Ni or Ni-silicide. Raman spectra typical of high quality exfoliated monolayer graphene were obtained for samples under optimised conditions. A fast cooling rate was found to be essential to the formation of monolayer graphene. Samples with Ni atop SiC produced the best monolayer graphene spectra with ~40% surface area coverage, whereas samples with Ni below SiC produced poorer quality graphene but 99% coverage. The flexibility of the sputtering process allows further optimization of the growth, with possibility of transferring the graphene to any insulator substrate in vacuum. We present a potential route for the production of graphene-on-insulator wafers, which would facilitate easy integration of graphene into modern semiconductor device process flows.