Low-temperature annealing of radiation-induced defects in carbon nanotube bundles

Abstract The annealing of radiation-induced defects in carbon nanotube bundles below room temperature has been investigated experimentally. Significant feature of this study is that electron irradiation (with an energy 1 MeV and fluence up to 10 16  el/cm 2 ) was carried out at liquid helium temperature. A detailed analysis of the resistance change over a wide temperature range (7–300 K) enables us to prove partial annealing of irradiation-induced defects at moderate temperatures. It is shown that such an annealing follows a first-order reaction in whole investigated temperature range. While at temperatures below 40 K, annealing is nonactivation, tunneling process; at higher temperatures (100 − 300 K) it becomes activated, with activation energy of ~ 0.05 eV. The value of discovered activation energy is close to the migration energy of interstitial carbon atom in graphite. Probably, observed annealing of radiation-induced defects in carbon nanotube bundles is also caused by the migration of interstitial carbon atoms between single nanotubes below room temperature.