AFM images of the polished 6H-SiC (0001) substrate (a) before and (b) after anneal; [(c) and (d)] zoom in image for marked area in (c), show the initial growth stage of epitaxial graphene prepared in our experiment. The inset of (d) shows the STM image of the formed moiré pattern scanned by Pt/Ir tip in air at , .
(a) Typical Raman spectra of a monolayer, a triple-layer, a six-layer and a ten-layer epitaxial graphene on the lightly N-doped 6H-SiC (0001), together with the reference spectra on the bared 6H-SiC (0001) substrate, as well as HOPG; (b) and (c) show the Raman peak positions for the G-band and the 2D-band with varying numbers of the epitaxial graphene layers, respectively; (d) and (e), respectively, illustrates the variation fits of the G-band and the 2D-band frequency as well as FWHM against the number of the epitaxial graphene layers.
(a) Raman spectra of monolayer epitaxial graphene grown on the different N-doped 6H-SiC (0001) substrates, together with the reference spectra on the bared 6H-SiC (0001) substrate; (b) Raman spectra of a monolayer, triple-layer, six-layer and ten-layer epitaxial graphene grown on the heavily N-doped 6H-SiC (0001); (c) and (d), respectively, illustrates the variation fits of the G-band and the 2D-band frequency of epitaxial graphene on the two differently N-doped substrates against the number of layers.
(Color online) (a) Fits of the Raman G-peak shifts of epitaxial graphene grown on different-doped 6H-SiC (0001) substrates with different layer numbers: on medium N-doped substrate (○), on high N-doped substrate (◻) and on highly P-doped substrate (△). (b) Schematic illustration of the charge transfer between epitaxial graphene and 6H-SiC (0001) system.
Room temperature Hall measurement parameter of bared 6H-SiC (0001) substrate.
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