Graphene nanoribbons on vicinal SiC surfaces by molecular beam epitaxy

We present a method of producing a densely ordered array of epitaxial graphene nanoribbons (GNRs) using vicinal SiC surfaces as a template, which consists of ordered pairs of (0001) terraces and nanofacets. Controlled selective growth of graphene on approximately 10 nm wide (0001) terraces with 10 nm spatial intervals allows GNR formation. By selecting the vicinal direction of SiC substrate, [11̄00], well-ordered GNRs with predominantly armchair edges are obtained. These structures, the high-density GNRs, enable us to observe the electronic structure at K points by angle-resolved photoemission spectroscopy, showing a clear band-gap opening of at least 0.14 eV.