title: Effect of SOCl2 treatment on electrical and mechanical properties of single-wall carbon nanotube networks.
abstract: Chemical modification by SOCl2 of an entangled network of purified single-wall carbon nanotubes, also known as 'bucky paper', is reported to profoundly change the electrical and mechanical properties of this system. Four-probe measurements indicate a conductivity increase by up to a factor of 5 at room temperature and an even more pronounced increase at lower temperatures. This chemical modification also improves the mechanical properties of SWNT networks. Whereas the pristine sample shows an overall semiconducting character, the modified material behaves as a metal. The effect of SOCl2 is studied in terms of chemical doping of the nanotube network. We identified the microscopic origin of these changes using SEM, XPS, NEXAFS, EDX, and Raman spectroscopy measurements and ab initio calculations. We interpret the SOCl2-induced conductivity increase by p-type doping of the pristine material. This conclusion is reached by electronic structure calculations, which indicate a Fermi level shift into the valence band, and is consistent with the temperature dependence of the thermopower.
authors.affiliation: Max-Planck-Institute for Solid State Research, Heisenbergstr.1, D-70569 Stuttgart, Germany. u.dettlaff@fkf.mpg.de
authors.forename: Urszula
authors.initials: U
authors.lastname: Dettlaff-Weglikowska
authors.forename: Viera
authors.initials: V
authors.lastname: Skákalová
authors.forename: Ralf
authors.initials: R
authors.lastname: Graupner
authors.forename: Sung Ho
authors.initials: SH
authors.lastname: Jhang
authors.forename: Byung Hoon
authors.initials: BH
authors.lastname: Kim
authors.forename: Hyun Jung
authors.initials: HJ
authors.lastname: Lee
authors.forename: Lothar
authors.initials: L
authors.lastname: Ley
authors.forename: Yung Woo
authors.initials: YW
authors.lastname: Park
authors.forename: Savas
authors.initials: S
authors.lastname: Berber
authors.forename: David
authors.initials: D
authors.lastname: Tománek
authors.forename: Siegmar
authors.initials: S
authors.lastname: Roth