Electrical characterization of multi-walled carbon nanotubes

Electrical characteristics of multi-walled carbon nanotubes (MWNTs) grown by chemical vapor deposition have been investigated as a function of the bias voltage, nanotubes length and temperature, in 2 and 4 terminal configurations. Nanotubes were deposited over metal electrodes using ac dielectrophoresis method. For better contacts between the nanotubes and electrodes, Ni and Pd films were deposited by an electroless deposition technique. Differential conductance was found to rise considerably with bias, and this effect was more pronounced for Ni. Using 2 and 4 terminal configurations, electrical resistance measurements for individual MWNTs were performed, and the results were interpreted using the model of nanotube as a resistive transmission line, where current at low bias flows mainly through the two outermost shells.