Specific stacking angles of bilayer graphene grown on atomic-flat and -stepped Cu surfaces

Bilayer graphene (BLG) exhibits unique properties depending on a stacking angle between the two layers of graphene. Although it has been known that BLGs having stacking angles of 0 degrees and 30 degrees can be obtained by chemical vapor deposition (CVD), not much is known yet about the effect of copper (Cu) surface on the decision of stacking angle, through which further fine control of the stacking angle could be possible. Here, we report that the crystal plane of Cu catalyst plays a critical role in the selection of the stacking angle of BLG, and provide experimental and computational evidence that an atomic-flat Cu (111) surface generates BLGs having 0 degrees and 30 degrees of stacking angle, while atomic-stepped Cu (311) and Cu (110) surfaces mainly produce small stacking angle BLGs with 3-5 degrees of stacking angle as a major product by CVD.