title: Tuning the band gap of graphene nanoribbons synthesized from molecular precursors.
abstract: A prerequisite for future graphene nanoribbon (GNR) applications is the ability to fine-tune the electronic band gap of GNRs. Such control requires the development of fabrication tools capable of precisely controlling width and edge geometry of GNRs at the atomic scale. Here we report a technique for modifying GNR band gaps via covalent self-assembly of a new species of molecular precursors that yields n = 13 armchair GNRs, a wider GNR than those previously synthesized using bottom-up molecular techniques. Scanning tunneling microscopy and spectroscopy reveal that these n = 13 armchair GNRs have a band gap of 1.4 eV, 1.2 eV smaller than the gap determined previously for n = 7 armchair GNRs. Furthermore, we observe a localized electronic state near the end of n = 13 armchair GNRs that is associated with hydrogen-terminated sp(2)-hybridized carbon atoms at the zigzag termini.
authors.affiliation: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
authors.forename: Yen-Chia
authors.initials: YC
authors.lastname: Chen
authors.forename: Dimas G
authors.initials: DG
authors.lastname: de Oteyza
authors.forename: Zahra
authors.initials: Z
authors.lastname: Pedramrazi
authors.forename: Chen
authors.initials: C
authors.lastname: Chen
authors.forename: Felix R
authors.initials: FR
authors.lastname: Fischer
authors.forename: Michael F
authors.initials: MF
authors.lastname: Crommie
mesh_terms: D003460:Crystallization / Q000379:methods*; D006108:Graphite / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008567:Membranes, Artificial; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D008567:Membranes, Artificial; D006108:Graphite