Rotation of Graphene on Cu during Chemical Vapor Deposition and Its Application to Control the Stacking Angle of Bilayer Graphene

Control of the stacking angle (theta S) of bilayer graphene (BLG) isessential for fundamental studies and applications of BLG. Especially, the use ofchemical vapor deposition (CVD) to grow high-quality BLG requires thiscontrol, but methods to achieve it are not available. Here, we found that graphenerotates during the CVD process, and this action can be exploited as a newstrategy to control theta S. The rotation of graphene was revealed by the populationchanges of AB-stacked BLG and 30 degrees-twisted BLG upon the growth time change;this change can only be explained by rotation of graphene. The rotation is largelyaffected by the edge state of graphene which can be tuned by growthtemperature. The rotation was observed through experimental results combinedwith theoretical calculation. The rotation can be blocked or accelerated bycontrolling the growth temperature, by which highly selective growth of AB-stacked BLG or 30 degrees-twisted BLG can be achieved.