Rotation of Graphene on Cu(111) Surface During Chemical Vapor Deposition and Controlling the Stacking Angle of Bilayer Graphene

Control of stacking angle (θ_S) of bilayer graphene (BLG) is an essential task for the understanding and applications of BLG whose properties largely depend on θ_S. Up to date, BLG is frequently obtained by a layer-by-layer stacking of individual single-layer graphene manually, which is inferior to the potential alternative by chemical vapor deposition (CVD) method in the view of chemical purity. In this presentation, we introduce graphene rotation on Cu(111) surface during the CVD process and its application to obtaining AB-stacked BLG (θ_S = 0°) and 30°-twisted-BLG by edge state engineering of the second layer of BLG. It was found that the graphene could be rotated because of the population changes of BLG, as evidenced by population variation of AB-stacked and 30°-twisted BLG. Since the rotation of graphene is largely affected by the edge state of graphene, it is important to tune the edge state of graphene by growth temperature. Changes in programmed growth temperatures lead to block or accelerate the rotation of BLG and resulted in highly selective growth of AB-stacked or 30°-twisted BLG can be achieved. Both experimental and calculation studies on the unprecedented graphene rotation phenomenon on Cu(111) surface during CVD will be discussed in detail.