Comeback of epitaxial graphene for electronics: large-area growth of bilayer-free graphene on SiC

Mattias Kruskopf,Rainer Stosch,Jens Baringhaus,Hans W Schumacher,Franz J Ahlers,Thomas Seyller,Frank Hohls,Klaus Pierz,Martin Götz,Christoph Tegenkamp,Stefan Wundrack,Davood Momeni Pakdehi,Jakob Lidzba,Thorsten Dziomba,Johannes Aprojanz

doi:10.1088/2053-1583/3/4/041002

Abstract

We present a new fabrication method for epitaxial graphene on SiC which enables the growth of ultra-smooth defect- and bilayer-free graphene sheets with an unprecedented reproducibility, a necessary prerequisite for wafer-scale fabrication of high quality graphene-based electronic devices. The inherent but unfavorable formation of high SiC surface terrace steps during high temperature sublimation growth is suppressed by rapid formation of the graphene buffer layer which stabilizes the SiC surface. The enhanced nucleation is enforced by decomposition of deposited polymer adsorbate which acts as a carbon source. Unique to this method are the conservation of mainly 0.25 and 0.5 nm high surface steps and the formation of bilayer-free graphene on an area only limited by the size of the sample. This makes the polymer-assisted sublimation growth technique a promising method for commercial wafer scale epitaxial graphene fabrication. The extraordinary electronic quality is evidenced by quantum resistance metrology at 4.2 K showing ultra-high precision and high electron mobility on mm scale devices comparable to state-of-the-art graphene.

Highlights

The success of graphene as a basis for new applications depends crucially on the reliability of the available technologies to fabricate large areas of homogenous high quality graphene layers
By using propane in a chemical vapor deposition process the versatility of the graphene growth is improved. (Michon et al 2010; Strupinski et al 2011) in spite of the progress achieved so far, the growth of high quality graphene in a reproducible manner remains challenging. (Eriksson et al 2012) The problem of the inherent high step edge formation caused by step bunching of the SiC substrate is not solved, leading to an increased electrical resistance (Ji et al 2012)(Low et al 2012) and anisotropic electronic properties (Yakes et al 2010)(Schumann et al 2012)
We describe a new sublimation growth method that leads to the formation of bilayer-free graphene on SiC with exceptionally shallow step heights and a layer size which is only limited by the dimensions of the sample. The core of this method is to form the surface stabilizing buffer layer by an external carbon source before the smooth surface morphology is destroyed by step bunching occurring at high temperature annealing

Summary

Introduction

The success of graphene as a basis for new applications depends crucially on the reliability of the available technologies to fabricate large areas of homogenous high quality graphene layers. We describe a new sublimation growth method that leads to the formation of bilayer-free graphene on SiC with exceptionally shallow step heights and a layer size which is only limited by the dimensions of the sample.

Results

Conclusion