Electronic Response and Bandstructure Modulation of Carbon Nanotubes in a Transverse Electrical Field

Abstract

The electronic properties of carbon nanotubes (NTs) in a uniform transverse field are investigated within a single orbital tight-binding (TB) model. For doped nanotubes, the dielectric function is found to depend not only on symmetry of the tube, but also on radius and Fermi level position. Bandgap opening/closing is predicted for zigzag tubes, while it is found that armchair tubes always remain metallic, which is explained by the symmetry in their configuration. The bandstructures for both types are considerably modified when the field strength is large enough to mix neighboring subbands.

One-dimensional Coulomb problem in Dirac materials

“…We have shown that manipulating the size of the band gap allows one to exclude from the discrete spectrum certain low-lying quantum states, for example, the ground state, in stark contrast to the nonrelativistic case. The band gap can be controlled, e.g., in the case of carbon nanotubes, by applying an external field [48][49][50][51][52] or via strain [56] or, in graphene nanoribbons, by choosing certain nanoribbons with a desirable geometry [57]. Alternatively, the strength of the interaction potential can be controlled by having multiple charged impurities [58] or changing the dielectric environment.…”

Origin of the Electric Property Change of a Single-Wall Carbon Nanotube Caused by Low-Energy Irradiation: Defects or Substrate Charging?

“…The energy barrier height observed after irradiation is not consistent with the field-induced band gap opening, either. The calculations show that the maximum value of the fieldinduced band gap is at most ∼0.1 eV [10,11], which is not sufficient to explain the almost insulating properties observed at room temperature. In fact, an energy barrier of ∼0.6 eV was observed for a SWNT whose room temperature electric properties were converted from metallic to semiconducting by irradiation [4].…”

“…Although the phenomena they observed are very similar to ours, they ascribed the conductivity decrease to a local band gap opening caused by irradiation-induced charging of dielectric SiO 2 layer just under the SWNT. In fact, theoretical calculations predict that a uniform [10] or inhomogeneous [11] electric field can open a gap in a metallic SWNT of specific chiralities. In their model, the recovery is explained by a release of the trapped charges caused by the strong electric field in the vicinity of the SWNT [7,8].…”

Metal-semiconductor transition and Fermi velocity renormalization in metallic carbon nanotubes

“…This perturbation may induce a transition in a SWNT changing the type of its electronic structure by opening/closing the band gap in the metallic/semiconducting nanotube. 2,3,4,5,6,8 It is important for applications in which such gap engineering can potentially be controlled locally, for instance by the field of a sharp tip, by a small molecule or by a local gate.…”

“…Different perturbations have been attempted to modify the electronic structure of A-SWNTs. 2,3,4,5,6,8,9,12,13,14,15 Our goal is to demonstrate, using symmetry arguments, whether a particular perturbation can open a gap at all and how the gap depends on the magnitude of the perturbation potential. We will show below that, with minor exceptions, this cannot be a linear dependence.…”