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 1⁢ 1^^-00 direction results in the appearance of pairs of (0001) macroterraces and (1⁢1^^-0⁢𝑛) macrofacets covered with graphene, as follows. A carpetlike carbon layer grows on the surface, covering both the macroterraces and macrofacets; it forms a (6⁢√×6⁢√) 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 11⁢2^^-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.