High-quality AB bilayer graphene films by direct solar-thermal chemical vapor deposition

Mass production of graphene by plasma or thermal chemical vapor deposition consumes much energy with potentially adverse effects on the environment. This work reports the use of a high-flux solar simulator that approximates the sun's spectrum and a cold-wall chemical vapor deposition reactor to demonstrate a renewable energy process for graphene growth. Synthesis of high-quality (I_{D}/I_{G} = 0.13) AB-stacked bilayer graphene with greater than 90% coverage is achieved on commercial polycrystalline copper in a one-step process and short time of 5 min. The graphene exhibits large grain sizes of at least 20 micron with spatial uniformity over a large area up to 20 mm in radius. The transmissivity and sheet resistance of the graphene films fall in the ranges of 92.8-95.3% and 2-4 kOhm/sq. Thus, direct solar capture provides a compelling option for graphene synthesis that can potentially decrease fabrication costs and environmental pollution.