title: Nitrogen-doped graphene films from chemical vapor deposition of pyridine: influence of process parameters on the electrical and optical properties.
abstract: Graphene films were produced by chemical vapor deposition (CVD) of pyridine on copper substrates. Pyridine-CVD is expected to lead to doped graphene by the insertion of nitrogen atoms in the growing sp(2) carbon lattice, possibly improving the properties of graphene as a transparent conductive film. We here report on the influence that the CVD parameters (i.e., temperature and gas flow) have on the morphology, transmittance, and electrical conductivity of the graphene films grown with pyridine. A temperature range between 930 and 1070 °C was explored and the results were compared to those of pristine graphene grown by ethanol-CVD under the same process conditions. The films were characterized by atomic force microscopy, Raman and X-ray photoemission spectroscopy. The optical transmittance and electrical conductivity of the films were measured to evaluate their performance as transparent conductive electrodes. Graphene films grown by pyridine reached an electrical conductivity of 14.3 × 10(5) S/m. Such a high conductivity seems to be associated with the electronic doping induced by substitutional nitrogen atoms. In particular, at 930 °C the nitrogen/carbon ratio of pyridine-grown graphene reaches 3%, and its electrical conductivity is 40% higher than that of pristine graphene grown from ethanol-CVD.
authors.affiliation: ENEA, Materials Technology Unit, Surface Technology Laboratory, Casaccia Research Centre,Via Anguillarese 301, 00123 Rome, Italy ; Istituto Italiano di Tecnologia, Graphene Labs, I-16163 Genova, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Capasso
authors.affiliation: ENEA, Materials Technology Unit, Surface Technology Laboratory, Casaccia Research Centre,Via Anguillarese 301, 00123 Rome, Italy.
authors.forename: Theodoros
authors.initials: T
authors.lastname: Dikonimos
authors.affiliation: ENEA, Fusion Technical Unit, Lab. of Nuclear Technologies, Via Enrico Fermi 45, 00044 Frascati (Rome), Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Sarto
authors.affiliation: Research Center on Nanotechnology Applied to Engineering of Sapienza (CNIS), SSNLab, Sapienza, University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Tamburrano
authors.affiliation: Research Center on Nanotechnology Applied to Engineering of Sapienza (CNIS), SSNLab, Sapienza, University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: De Bellis
authors.affiliation: Research Center on Nanotechnology Applied to Engineering of Sapienza (CNIS), SSNLab, Sapienza, University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy.
authors.forename: Maria Sabrina
authors.initials: MS
authors.lastname: Sarto
authors.affiliation: Dipartimento di Ingegneria dell'Informazione, delle Infrastrutture e dell'Energia Sostenibile (DIIES), Università "Mediterranea" di Reggio Calabria, 89122 Reggio Calabria, Italy.
authors.forename: Giuliana
authors.initials: G
authors.lastname: Faggio
authors.affiliation: Dipartimento di Ingegneria dell'Informazione, delle Infrastrutture e dell'Energia Sostenibile (DIIES), Università "Mediterranea" di Reggio Calabria, 89122 Reggio Calabria, Italy.
authors.forename: Angela
authors.initials: A
authors.lastname: Malara
authors.affiliation: Dipartimento di Ingegneria dell'Informazione, delle Infrastrutture e dell'Energia Sostenibile (DIIES), Università "Mediterranea" di Reggio Calabria, 89122 Reggio Calabria, Italy.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Messina
authors.affiliation: ENEA, Materials Technology Unit, Surface Technology Laboratory, Casaccia Research Centre,Via Anguillarese 301, 00123 Rome, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Lisi
keywords: carbon; electrical conductivity; nitrogen doping; optical conductivity; transparent conductor