Abstract
We demonstrate the growth of continuous monolayer graphene films with millimeter-sized domains on Cu foils under intrinsically safe, atmospheric pressure growth conditions, suitable for application in roll-to-roll reactors. Previous attempts to grow large domains in graphene have been limited to isolated graphene single crystals rather than as part of an industrially useable continuous film. With both appropriate pre-treatment of the Cu and optimization of the CH4 supply, we show that it is possible to grow continuous films of monolayer graphene with millimeter scale domains within 80 min by chemical vapour deposition. The films are grown under industrially safe conditions, i.e., the flammable gases (H2 and CH4) are diluted to well below their lower explosive limit. The high quality, spatial uniformity, and low density of domain boundaries are demonstrated by charge carrier mobility measurements, scanning electron microscope, electron diffraction study, and Raman mapping. The hole mobility reaches as high as ~5,700 cm2 V−1 s−1 in ambient conditions. The growth process of such high-quality graphene with a low H2 concentration and short growth times widens the possibility of industrial mass production.
Highlights
The safety issue of the CVD process is usually ignored, despite its importance in industrial production
We demonstrate the growth of continuous monolayer graphene with millimeter-sized domains using diluted H2 (2%) in 80 min
The Cu foil is annealed under pure Ar after the temperature ramps to 1030 °C under pure Ar
Summary
The safety issue of the CVD process is usually ignored, despite its importance in industrial production. There are several reports on graphene growth using no H213,32,33 or diluted H222,29,34,35–39, their charge carrier mobilities are limited below ~4, 000 cm2V−1s−1, which is not qualified for “electronic-grade” applications[8]. The growth of graphene with a high charge carrier mobility is still a challenge under industrially safe CVD conditions. We demonstrate the growth of continuous monolayer graphene with millimeter-sized domains using diluted H2 (2%) in 80 min. The hole mobility reaches as high as 5,700 cm2V−1s−1, the highest value among the reported mobilities using low concentrations of H2. We achieve this by combining electropolishing and non-reductive annealing of the Cu foils with optimizing the CH4 concentration. This work brings the current growth method of graphene a large step towards scalable and safe production
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