Measuring the High Frequency Response of Individual Carbon Nanotubes

Carbon nanotubes are nanometer diameter hollow tubes of carbon that are ideal one-dimensional conductors. They are being developed as elements in molecular electronics. Extensive studies up to this time have focused on DC properties of nanotubes. I report progress toward measurements of the dynamic conductance of individual carbon nanotubes at GHz to THz frequencies using terahertz time-domain spectroscopy. In this method, individual single-wall carbon nanotubes are incorporated into microfabricated antennas and used as receivers of broadband THz radiation. A variable time delay between two incident pulses is used to gain information about the frequency dependence of the antenna response. If the nanotube has the predicted length-dependent resonance [Burke, P. J., IEEE Transactions on Nanotechnology V. 1, p. 129 (2002)], then this should be clear in the antenna response. Knowledge of the spectral response of carbon nanotubes is important for applications in electronic interconnects as well as a confirmation of certain aspects of Luttinger liquid theory.