Characterization of thermal transport in multiwalled carbon nanotube using FIB irradiation

Thermal conductance of an individual multiwalled carbon nanotube was measured as a function of its length. Focused ion beam was used to shorten a 4.8 micrometer-long nanotube to 2.4, 1.2, 0.6, and 0.3-micrometer-long specimens on a hot-film sensor. As the nanotube is shorten, the conductance decreases more than expected by the diffusive thermal conduction theory. We treated two nanotubes of 64nm and 85nm diameters, both of which showed quasi-ballistic phonon transport. This is the first experiment to quantitatively investigate the contribution of phonons with long free paths in multiwalled carbon nanotube. The principle of thermal measurement, amorphous carbon induced by the ion beam, and considerable errors are also explained.