Quantifying Single-Carbon Nanotube-Electrode Contact via the Nanoimpact Method.

A new methodology is developed to enable the measurement of the resistance across individual carbon nanotube-electrode contacts. Carbon nanotubes (CNTs) are suspended in the solution phase and occasionally contact the electrified interface, some of which bridge a micron-sized gap between two microbands of an interdigitated gold electrode. A potential difference is applied between the contacts and the magnitude of the current increase after the arrival of the CNT gives a measure of the resistance associated with the single CNT-gold contact. These experiments reveal the presence of a high contact resistance (∼50 MΩ), which significantly dominates the charge-transfer process. Further measurements on ensembles of CNTs made using a dilute layer of CNTs affixed to the interdigitated electrode surface and measured in the absence of solvent showed responses consistent with the same high value of contact resistance.