Atmospheric Pressure Catalytic Vapor Deposition of Graphene on Liquid In and Cu-In Alloy Substrates

Maryam A Saeed,Brian Derby,Ian A Kinloch

doi:10.3390/catal11111318

Abstract

Liquid substrates are great candidates for the growth of high-quality graphene using chemical vapour deposition (CVD) due to their atomically flat and defect free surfaces. A detailed study of graphene growth using atmospheric pressure CVD (APCVD) on liquid indium (In) was conducted. It was found that the effect of the growth parameters on the quality of the graphene produced is highly dependent on the properties of the substrate used. A short residence time of 6.8 sec for the reactive gases led to a high graphene quality, indicating the good catalytic behaviour of In. The role of hydrogen partial pressure was found to be crucial, with monolayer and bilayer graphene films with a low defect density obtained at low PH2 (38.6 mbar), whilst more defective, thicker graphene films with a partial coverage being obtained at high PH2 (74.3 mbar). The graphene deposition was insensitive to growth time as the graphene growth on liquid In was found to self-limit to bilayer. For further investigation, five compositions of Cu-In alloys were made by arc-melting. Graphene was then grown using the optimum conditions for In and the quality of the graphene was found to degrade with increasing Cu wt.%. This work will aid the future optimisation of the growth conditions based upon the substrate’s properties.

Highlights

Graphene synthesis techniques fall either into the categories of top-down or bottomup
Bottom-up approaches start with a carbon precursor such as methane or acetylene which is deposited onto a substrate to grow high quality graphene films via chemical vapor deposition (CVD) [5,6,7]
The quality of the CVD graphene film varies with the substrates and the growth conditions used

Summary

Introduction

Graphene synthesis techniques fall either into the categories of top-down or bottomup. Liquid Sn and Cu–Sn alloys were investigated, showing that altering the growth conditions with the change in the catalytic activity of the substrates directly affect the number of layers and defects density of the graphene grown [10]. The CVD graphene is grown on solid substrates, where the morphology (e.g., surface impurities and grain boundaries) affects the nucleation density and the quality of the graphene produced [11] Substrates in their liquid phase provide a defect-free surface with no grain boundaries and lead to a uniform graphene deposition [10,12,13,14,15,16,17]. Gallium (Ga), indium (In), and tin (Sn) have been used a liquid growth substrates for graphene [18,19]

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Results

Conclusion