Effects of geometric structures and temperature on electronic properties of double-walled armchair carbon nanotubes

Abstract

Electronic structures of armchair double-walled carbon nanotubes are calculated by the tight-binding model. The energy dispersions near Fermi level are significantly affected by the translation and rotation between the inner and outer nanotubes. There are intersecting linear bands or parabolic bands with energy spacings in the low energy region. The main characteristics of the subbands would be directly reflected in the density of states and the optical excitations. The absorption frequencies come from the energies between the band-edge states, and the low-frequency optical absorptions would be further modulated by temperature. Several absorption peaks might be created at finite temperature due to the variations on the carrier concentration near the Fermi level. The calculated results would be useful to examine the effects of nanotube configurations and temperature on the electronic properties.