title: Atomic structure of epitaxial graphene sidewall nanoribbons: flat graphene, miniribbons, and the confinement gap.
abstract: Graphene nanoribbons grown on sidewall facets of SiC have demonstrated exceptional quantized ballistic transport up to 15 μm at room temperature. Angular-resolved photoemission spectroscopy (ARPES) has shown that the ribbons have the band structure of charge neutral graphene, while bent regions of the ribbon develop a bandgap. We present scanning tunneling microscopy and transmission electron microscopy of armchair nanoribbons grown on recrystallized sidewall trenches etched in SiC. We show that the nanoribbons consist of a single graphene layer essentially decoupled from the facet surface. The nanoribbons are bordered by 1-2 nm wide bent miniribbons at both the top and bottom edges of the nanoribbons. We establish that nanoscale confinement in the graphene miniribbons is the origin of the local large band gap observed in ARPES. The structural results presented here show how this gap is formed and provide a framework to help understand ballistic transport in sidewall graphene.
authors.affiliation: UR1 CNRS/Synchrotron SOLEIL , Saint-Aubin, 91192 Gif sur Yvette, France.
authors.forename: Irene
authors.initials: I
authors.lastname: Palacio
authors.forename: Arlensiú
authors.initials: A
authors.lastname: Celis
authors.forename: Maya N
authors.initials: MN
authors.lastname: Nair
authors.forename: Alexandre
authors.initials: A
authors.lastname: Gloter
authors.forename: Alberto
authors.initials: A
authors.lastname: Zobelli
authors.forename: Muriel
authors.initials: M
authors.lastname: Sicot
authors.forename: Daniel
authors.initials: D
authors.lastname: Malterre
authors.forename: Meredith S
authors.initials: MS
authors.lastname: Nevius
authors.forename: Walt A
authors.initials: WA
authors.lastname: de Heer
authors.forename: Claire
authors.initials: C
authors.lastname: Berger
authors.forename: Edward H
authors.initials: EH
authors.lastname: Conrad
authors.forename: Amina
authors.initials: A
authors.lastname: Taleb-Ibrahimi
authors.forename: Antonio
authors.initials: A
authors.lastname: Tejeda
mesh_terms: D006108:Graphite / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D016252:Microscopy, Scanning Tunneling; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure*
chemical_list: D037742:Nanotubes, Carbon; D006108:Graphite
keywords: Graphene; HR-XTEM; STM; atomic structure; band gap; ribbon