Transmission line impedance of carbon nanotube thin films for chemical sensing applications.

ORAL

Abstract

We measure the resistance and frequency-dependent (50 Hz - 20 KHz) gate capacitance of carbon nanotube (CNT) thin films as a function of DC gate bias under ambient conditions, in ultra-high vacuum, and under low-pressure (10$^{-6}$ torr) gaseous environments of water, acetone, and argon. We have analyzed our results by modeling the CNT film as an RC transmission line. We show that changes in the measured capacitance as a function of gate bias and analyte pressure can be explained by the changes in the CNT film resistivity alone; the electrostatic gate capacitance of the CNT film does not depend on gate voltage or chemical analyte adsorption to within the resolution of our measurement. We also show that the resistance of the CNT film is enormously sensitive to exposure to low pressures ($<$ 10$^{-6}$ Torr) of analytes. This research was supported by the Laboratory for Physical Sciences and the U.S. Army Research Laboratory MICRA Program. MI received support from the Director of Central Intelligence Postdoctoral Fellowship program.

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Authors

  • G. Esen

    • Department of Physics and Center for Superconductivity Research, University of Maryland, College Park, Maryland 20742

  • M.S. Fuhrer

    • Department of Physics and Center for Superconductivity Research, University of Maryland, College Park, Maryland 20742
    • Dept. of Physics and Center for Superconductivity Research, Univ. of Maryland, College Park
    • Department of Physics and Center for Superconductivity Research, University of Maryland, College Park, MD 20742, USA
    • Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, MD 20742-4111

  • Jianhao Chen

    • Laboratory for Physical Sciences and Department of Physics, University of Maryland, College Park, Maryland 20742
    • Physics Department and the Material Research Science and Engineering Center, Unversity of Maryland, College Park, MD 20742
    • Physics Department and the Material Research Science and Engineering Center, University of Maryland, College Park, MD 20742

  • Masa Ishigami

    • Laboratory for Physical Sciences and Department of Physics, University of Maryland, College Park, Maryland 20742
    • University of Maryland
    • Physics Department and the Material Research Science and Engineering Center, Unversity of Maryland, College Park, MD 20742

  • E. D. Williams

    • Laboratory for Physical Sciences and Department of Physics, University of Maryland, College Park, Maryland 20742
    • U. Maryland, College Park