title: Phonon-assisted electroluminescence from metallic carbon nanotubes and graphene.
abstract: We report on light emission from biased metallic single-wall carbon nanotube (SWNT), multiwall carbon nanotube (MWNT) and few-layer graphene (FLG) devices. SWNT devices were assembled from tubes with different diameters in the range 0.7-1.5 nm. They emit light in the visible spectrum with peaks at 1.4 and 1.8 eV. Similar peaks are observed for MWNT and FLG devices. We propose that this light emission is due to phonon-assisted radiative decay from populated pi* band states at the M point to the Fermi level at the K point. Since for most carbon nanotubes as well as for graphene the energy of unoccupied states at the M point is close to 1.6 eV, the observation of two emission peaks at approximately 1.6 +/- approximately 0.2 eV could indicate radiative decay under emission or absorption of optical phonons, respectively.
authors.affiliation: Institut für Nanotechnologie, Karlsruhe Institute of Technology, Karlsruhe, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Essig
authors.forename: C W
authors.initials: CW
authors.lastname: Marquardt
authors.forename: A
authors.initials: A
authors.lastname: Vijayaraghavan
authors.forename: M
authors.initials: M
authors.lastname: Ganzhorn
authors.forename: S
authors.initials: S
authors.lastname: Dehm
authors.forename: F
authors.initials: F
authors.lastname: Hennrich
authors.forename: F
authors.initials: F
authors.lastname: Ou
authors.forename: A A
authors.initials: AA
authors.lastname: Green
authors.forename: C
authors.initials: C
authors.lastname: Sciascia
authors.forename: F
authors.initials: F
authors.lastname: Bonaccorso
authors.forename: K-P
authors.initials: KP
authors.lastname: Bohnen
authors.forename: H v
authors.initials: Hv
authors.lastname: Löhneysen
authors.forename: M M
authors.initials: MM
authors.lastname: Kappes
authors.forename: P M
authors.initials: PM
authors.lastname: Ajayan
authors.forename: M C
authors.initials: MC
authors.lastname: Hersam
authors.forename: A C
authors.initials: AC
authors.lastname: Ferrari
authors.forename: R
authors.initials: R
authors.lastname: Krupke
mesh_terms: D003460:Crystallization / Q000379:methods*; D004563:Electrochemistry / Q000379:methods*; D006108:Graphite / Q000737:chemistry*; D008163:Luminescent Measurements / Q000379:methods*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008670:Metals / Q000737:chemistry; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010316:Particle Size; D017785:Photons; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D008670:Metals; D037742:Nanotubes, Carbon; D006108:Graphite