title: Transport mechanisms in metallic and semiconducting single-wall carbon nanotube networks.
abstract: A fundamental understanding of the conduction mechanisms in single-wall carbon nanotube (SWCNT) networks is crucial for their use in thin-film transistors and conducting films. However, the uncontrollable mixture state of metallic and semiconducting SWCNTs has always been an obstacle in this regard. In the present study, we revealed that the conduction mechanisms in nanotube networks formed by high-purity metallic and semiconducting SWCNTs are completely different. Quantum transport was observed in macroscopic networks of pure metallic SWCNTs. However, for semiconducting SWCNT networks, Coulomb-gap-type conduction was observed, due to Coulomb interactions between localized electrons. Crossovers among a weakly localized state and strongly localized states with and without Coulomb interactions were observed for transport electrons by varying the relative content of metallic and semiconducting SWCNTs. It was found that hopping barriers, which always exist in normal SWCNT networks and are serious obstacles to achieving high conductivity, were not present in pure metallic SWCNT networks.
authors.affiliation: Department of Physics, Tokyo Metropolitan University, Hachioji, 192-0397 Tokyo, Japan. yanagi@phys.metro-u.ac.jp
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yanagi
authors.forename: Hiroki
authors.initials: H
authors.lastname: Udoguchi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Sagitani
authors.forename: Yugo
authors.initials: Y
authors.lastname: Oshima
authors.forename: Taishi
authors.initials: T
authors.lastname: Takenobu
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Kataura
authors.forename: Takao
authors.initials: T
authors.lastname: Ishida
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Matsuda
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Maniwa