Growth of self-assembled graphene nanoribbons on SiC substrates.

Graphene nanoribbons (GNRs) hold promise for future nanoelectronics due to their unique band structure. Quantum confinement effects are observed in GNRs, and their bandgap energies increase with inverse proportionality to the GNR width. However, existing lithographic patterning methods cause disordered edges to form during the etching process creating dangling bonds that degrade the electrical properties of the GNR. To overcome these problems, structured silicon carbide (SiC) has been used as a template for selective growth of GNRs, which show outstanding ballistic transport with an electronic mean free path up to 15 μm [1, 2]. In this study, we have demonstrated the growth of narrow GNRs (~40 nm width) with improved structural properties using a surface pre-treatment. This method restrains SiC terrace edge step-flow during the annealing process, helping to form GNRs with the shape of the patterned SiC. The longitudinal and Hall magnetoresistance of GNRs are measured at low temperature using a six-terminal Hall bar geometry and the structural characteristics are demonstrated with atomic force microscopy (AFM), conductive AFM, and field emission scanning electron microscopy.

[1] Y. Hu et al., J. Phys. D: Appl. Phys. 45, 154010 (2012)
[2] J. Baringhaus et al., Nature 506, 349 (2014)