Atmospheric Pressure Chemical Vapor Deposition of Twisted Bilayer Graphene on Copper Foil Substrates

Atmospheric pressure chemical vapor deposition (APCVD) of graphene bilayers on
copper foil substrates represents a promising paradigm for the fabrication of Bernal stacked and
twisted bilayer graphene samples. Large scale growth techniques will be essential in developing
the potential applications of bilayer graphene, such as ultra high frequency field effect transistors
or novel photonic devices. Using a quartz tube and tube furnace, copper foil substrates, argon
and hydrogen forming gas, and a methane carbon feedstock, we studied a variety of different
APCVD recipes to determine the optimal growth parameters for depositing graphene bilayers.
Additionally, various copper substrate pretreatment techniques were tested, including surface
etching, electrochemical polishing, wet oxidation, and argon annealing. Preliminary results
suggest that increased bilayer grain sizes can be achieved by flowing higher methane
concentrations for longer time periods during the growth stage, and optical microscopy of single
and bilayer grain alignment suggest that small twist angles can be achieved using our APCVD method.