Fig. S2: a, An optical image of large-area graphenes after PMMA-mediated nanotransfer process on a silicon wafer. b, Schematic representation of the SLG device array. c, The enlarged optical image of a representative device. The average width of graphene sheets is 70 m. d, A representative Raman spectrum of the grown graphene. e, A representative high-resolution TEM image of SLG.
Fig. S3. Intensity profile plot along the line indicated by the arrows in Fig. 3e. The intensities of the diffraction spots from outer hexagon is equivalent to that from inner hexagon, confirms that our graphene samples are single-layer1.
Fig. S4. XPS spectra of a SLG sample before and after plasma methylation. Inset shows the enlarged N 1s XPS spectra. We find that the amount of O and N atoms were strongly suppressed after plasma treatment.
