Electrical and mechanical properties of distorted carbon nanotubes

Abstract

We have calculated the effects of structural distortions of armchair carbon nanotubes on their electrical transport properties. We found that the bending of the nanotubes decreases their transmission function in certain energy ranges and leads to an increased electrical resistance. Electronic structure calculations show that these energy ranges contain localized states with significant σ-π hybridization resulting from the increased curvature produced by bending. Our calculations of the contact resistance show that the large contact resistances observed for SWNTs are likely due to the weak coupling of the NT to the metal in side bonded NT-metal configurations.Carbon nanotubes (NTs) can be metallic or semiconducting. They have high mechanical strength and good thermal conductivity [1], properties that make them potential building blocks of a new, carbon-based, nanoelectronic technology [2][3][4][5]. Conduction in defect-free NTs, especially at low temperatures, can be ballistic, thus involving little energy dissipation within the NT [6]. Furthermore, NTs are expected to behave like quasi onedimensional systems (Q1D) with quantized electrical resistance, which, for metallic armchair nanotubes at low bias should be about 6 kΩ (h/4e2 ). The experimentally observed behavior is, however, quite different. The contact resistance of single-wall nanotubes (SWNTs) with metal electrodes is generally quite high. Furthermore, at low temperatures a localization of the wavefunction in the nanotube segment contained between the metal electrodes is observed that leads to Coulomb blockade phenomena [7]. The latter observation suggests that a barrier or bad-gap develops along the NT near its contact with the metal. In an effort to understand the origin of these discrepancies we have used Green's function techniques to calculate the effect of the modification of the NTs by bending on their electronic structure and electric transport properties. We also investigated the effects of the strength of the NT-metal pad interaction on the value of the contact resistance.

Atomic and electronic structure in collapsed carbon nanotubes evidenced by scanning tunneling microscopy

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Moiré Patterns Observed in Bi Layer Graphene Irradiated with High Energetic Protons

“…Due that the effect of rotation in between planes of graphene was considered, the effect is similar to the nanotubes subjected to distortion as reported by Rochefort et al [23] they reported the effect of structural distortions of armchair carbon nanotubes on their electronic properties. One of the effects produced is to open of band gaps at some symmetric point of the FBZ, especially at the K point of the reciprocal space.…”

A molecular structural mechanics model applied to the static behavior of single-walled carbon nanotubes: New general formulation

“…For instance, CNTs show a singular coupling between mechanical strain and electrical conductivity [3,4], becoming ideal candidates for making nanosensors and nano electro-mechanical systems (NEMS), with promising applications in robotics and biomechanics.…”