The carbon's solubility into copper is incredibly low and thus generally floor diffusion and nucleation of carbon atoms are associated. Because of this along with the growth kinetics, the graphene thickness is restricted to predominantly a monolayer. The large edge would be that the graphene is usually developed on Cu https://www.facebook.com/permalink.php?story_fbid=pfbid0YUx5gnWXKYpDdf4zZk9dagBnHDWXdmfYSKKbYe4g51gyU5jdQ8jNVAQcdH6jE5jjl&id=61562415773754&__cft__[0]=AZVQRBH89egHZ9zUXrup0rUzNx2chOEfnhEmoV1AJVWzuIWOV1HMyrwmY1gmmB6L2aN8RrcWI_EX2pEtUBA3BW28dXt2MwT-Zteu3hLWf3D_7AvXTNPMmaZk2AeFPaR2hM4kAjobJyz6IGFkiOe6y51jRfkxTRY92OVVytQrzyDSpF59ivTLaUIMvvt8hvXYRoI0KMuId3bwnBfnVek3Xu1K&__tn__=%2CO%2CP-R