Extended Data Fig. 9: Statistics of residual nanoparticles on different transferred graphene.

a–c, AFM images of residual nanoparticles on transferred graphene films after UHV annealing. The films are grown by traditional CVD on Cu(111) (a), traditional CVD on Cu foil (b) and ICP–CVD on Cu(111) (c, 150 μm × 90 μm). Transferred ICP–CVD graphene films appear wrinkle-free and nanoparticle-free during this large-scale measurement. Scale bars in a–c are 1 μm, 1 μm and 30 μm, respectively.