Lattice-oriented catalytic growth of graphene nanoribbons on heteroepitaxial nickel films.

Graphene nanoribbons (GNRs) are a promising material for electronic applications, because quantum confinement in a one-dimensional nanostructure can potentially open the band gap of graphene. However, it is still a challenge to synthesize high-quality GNRs by a bottom-up approach without relying on lithographic techniques. In this work, we demonstrate lattice-oriented catalytic growth of single-layer GNRs on the surface of a heteroepitaxial Ni film. Catalytic decomposition of a poly(methyl methacrylate) film on the Ni(100) film at 1000 °C gives narrow nanoribbons with widths of 20-30 nm, which are aligned along either [011] or [011] directions of the Ni lattice. Furthermore, low-energy electron microscope (LEEM) analysis reveals that orientation of carbon hexagons in these GNRs is highly controlled by the underlying Ni(100) lattice, leading to the formation of zigzag edges. This heteroepitaxial approach would pave a way to synthesize nanoribbons with controlled orientation for future development of electronic devices based on graphene nanostructures.