Oxygen plasma effects on the electrical conductance of single-walled carbon nanotube bundles

We report the electrical properties of single-walled carbon nanotube bundles aligned between two electrodes with a gap of 8 mu m by the alternating current dielectrophoresis method. The resistance increased exponentially as the number of structural defects increased from the oxygen plasma treatment. However, no noticeable change was observed in the carrier concentration and tube-tube interaction. The resistance dependence on the plasma treatment time was explained on the basis of the localization of electron states at defect sites. The aspects of the defects were examined by measuring the effects of ammonia adsorption on the conductance of the device.