Carbon Nanotubes Defects

Four major categories of carbon nanotubes exist and include topological, rehybridization, incomplete bonding and doping defects. Topological defects are localized and do not change the lengths of the carbon nanotubes, but only affect electronic structures on sidewalls in some locations along the nanotube. Graphite is mostly affected by the incomplete bonding defect where dislocations and vacancies arise. Incomplete bonding and doping defects have the ability to increase the chemical reactivity and electrical conductivity of carbon nanotubes.

Behavior in Electricity

Carbon nanotubes have unique electrical properties, and they are either semiconducting or metallic. These properties depend on the chirality and tube diameter of the Carbon nanotubes. The chirality of carbon nanotubes is represented by the integer pair (n and m). Carbon nanotubes with n – m = 3j (where j is a nonzero integer) are metallic. All the other carbon nanotubes are semiconducting. Carbon nanotubes are highly anisotropic in their dielectric properties, and this arises from their uni-dimensional structures. This increases the efficiency of carrying high current electricity in carbon nanotubes with minimum loss in terms of heating. The current density in most metallic conductors is limited by electromigration. Conducting carbon nanotubes have high current densities due to their small cross-sectional areas. Semiconducting SWCNTs have the advantage of operating at high frequencies and are used in integrated circuits to increase their number densities and speeds. SWCNTs have low electron scattering, which makes them useful for building transistors. Carbon nanotubes are also used for high voltage applications, such as providing reduced initiation voltage required for corona discharges (Chen 1).