Formation of graphene nanoribbons on the macrofacets of vicinal 6H -SiC(0001) surfaces

Thermal decomposition of vicinal 6H-SiC(0001) surfaces with miscut angles toward the [11¯00] direction results in the appearance of pairs of (0001) macroterraces and (11¯0n) macrofacets covered with graphene, as follows. A carpetlike carbon layer grows on the surface, covering both the macroterraces and macrofacets; it forms a (63×63) buffer layer on the former ones, whereas its partial periodic bonding with the SiC steps on the latter ones generates a pseudographene nanoribbon (pseudo-GNR) array. The nanoribbons have a width of 1.7-1.8 nm and are aligned in the [112¯0] direction with a spatial periodicity of 3.3 nm. Scanning tunneling spectroscopy at a nanoribbon indicated a 0.4-0.5 eV energy gap and the Raman spectroscopy analysis of the pseudo-GNR array showed the absence of the 2D peak and the polarization dependence of the G and D peaks, which is typical of the armchair-edge nanoribbon.