title: Direct oriented growth of armchair graphene nanoribbons on germanium.
abstract: Graphene can be transformed from a semimetal into a semiconductor if it is confined into nanoribbons narrower than 10 nm with controlled crystallographic orientation and well-defined armchair edges. However, the scalable synthesis of nanoribbons with this precision directly on insulating or semiconducting substrates has not been possible. Here we demonstrate the synthesis of graphene nanoribbons on Ge(001) via chemical vapour deposition. The nanoribbons are self-aligning 3° from the Ge〈110〉 directions, are self-defining with predominantly smooth armchair edges, and have tunable width to <10 nm and aspect ratio to >70. In order to realize highly anisotropic ribbons, it is critical to operate in a regime in which the growth rate in the width direction is especially slow, <5 nm h(-1). This directional and anisotropic growth enables nanoribbon fabrication directly on conventional semiconductor wafer platforms and, therefore, promises to allow the integration of nanoribbons into future hybrid integrated circuits.
authors.affiliation: Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Jacobberger
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, USA.|Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Kiraly
authors.affiliation: Department of Engineering Physics, École Polytechnique de Montréal, Montréal, Québec, Canada H3C 2A7.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Fortin-Deschenes
authors.affiliation: Department of Chemistry, Université de Montréal, Montréal, Québec, Canada H3C 3JT.
authors.forename: Pierre L
authors.initials: PL
authors.lastname: Levesque
authors.affiliation: Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Kyle M
authors.initials: KM
authors.lastname: McElhinny
authors.affiliation: Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Gerald J
authors.initials: GJ
authors.lastname: Brady
authors.affiliation: Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Rojas Delgado
authors.affiliation: Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Susmit
authors.initials: S
authors.lastname: Singha Roy
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, USA.|Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Mannix
authors.affiliation: Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Max G
authors.initials: MG
authors.lastname: Lagally
authors.affiliation: Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Paul G
authors.identifier: http://orcid.org/0000-0003-0421-6792
authors.initials: PG
authors.lastname: Evans
authors.affiliation: Department of Engineering Physics, École Polytechnique de Montréal, Montréal, Québec, Canada H3C 2A7.
authors.forename: Patrick
authors.initials: P
authors.lastname: Desjardins
authors.affiliation: Department of Chemistry, Université de Montréal, Montréal, Québec, Canada H3C 3JT.
authors.forename: Richard
authors.identifier: http://orcid.org/0000-0002-9021-4656
authors.initials: R
authors.lastname: Martel
authors.affiliation: Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.|Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Hersam
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: Nathan P
authors.initials: NP
authors.lastname: Guisinger
authors.affiliation: Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Arnold