The electronic properties of semimetallic (12,0) carbon nanotubes in the presence of a variety of monovacancy, divacancy, and hexavacancy defects were investigated by using first-principles density functional theory combined with the non-equilibrium Green’s function technique. It was shown that defect states related to the vacancies hybridize with the extended states of the nanotubes to modify the band edge, and change the energy gap. As a consequence, the nanotube conductance was not a monotonic function of the defect size and geometry. Paradoxically, tetravacancy and hexavacancy nanotubes have higher conductance than divacancy nanotubes, which was due to the presence of mid-gap states originating from the defect, thereby enhancing the conductance.

Atomic Vacancy Defects in the Electronic Properties of Semi-Metallic Carbon Nanotubes. H.Zeng, J.Zhao, H.Hu, J.P.Leburton: Journal of Applied Physics, 2011, 109[8], 083716