Reversibility, Dopant Desorption, and Tunneling in the Temperature-Dependent Conductivity of Type-Separated, Conductive Carbon Nanotube Networks

Teresa M. Barnes, Jeffrey L. Blackburn, Jao van de Lagemaat, Timothy J. Coutts, Michael J. Heben

Research output: Contribution to journalArticlepeer-review

111 Scopus Citations

Abstract

We present a comprehensive study of the effects of doping and temperature on the conductivity of single-walled carbon nanotube (SWNT) networks. We investigated nearly type-pure networks as well as networks comprising precisely tuned mixtures of metallic and semiconducting tubes. Networks were studied in their as-produced state and after treatments with nitric acid, thionyl chloride, and hydrazine to explore the effects of both intentional and adventitious doping. For intentionally and adventitiously doped networks, the sheet resistance (Rs) exhibits an irreversible increase with temperature above ∼350 K. Dopant desorption is shown to be the main cause of this increase and the observed hysteresis in the temperature-dependent resistivity. Both thermal and chemical dedoping produced networks free of hysteresis. Temperature-programmed desorption data showed that dopants are most strongly bound to the metallic tubes and that networks consisting of metallic tubes exhibit the best thermal stability. At temperatures below the dopant desorption threshold, conductivity in the networks is primarily controlled by thermally assisted tunneling through barriers at the intertube or interbundle junctions.

Original languageAmerican English
Pages (from-to)1968-1976
Number of pages9
JournalACS Nano
Volume2
Issue number9
DOIs
StatePublished - 2008

NREL Publication Number

  • NREL/JA-520-44672

Keywords

  • Carbon nanotubes
  • Doping
  • Electrical properties
  • Hysteresis
  • Optical properties
  • Resistivity
  • Temperature dependence

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