Eur. Phys. J. B (2014) 87: 126
https://doi.org/10.1140/epjb/e2014-41103-9

Regular Article

Bundle versus network conductivity of carbon nanotubes separated by type

Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, 1525 Budapest, Hungary

^a Present address: Center for Nanoscale Science and Engineering, Departments of Chemistry and Chemical & Environmental Engineering, University of California, Riverside, CA 92521, USA.
^b e-mail: kamaras.katalin@wigner.mta.hu

Received: 25 December 2013
Received in final form: 20 April 2014
Published online: 9 June 2014

Abstract

We report wide-range optical investigations on transparent conducting networks made from separated (semiconducting, metallic) and reference (mixed) single-walled carbon nanotubes, complemented by transport measurements. Comparing the intrinsic frequency-dependent conductivity of the nanotubes with that of the networks, we conclude that higher intrinsic conductivity results in better transport properties, indicating that the properties of the nanotubes are at least as much important as the contacts. We find that HNO₃ doping offers a larger improvement in transparent conductive quality than separation. Spontaneous dedoping occurs in all samples but is most effective in films made of doped metallic tubes, where the sheet conductance returns close to its original value within 24 h.