Carbon nanotubes are allotropes of carbon with a cylindrical nanostructure, and can be categorized into single-walled nanotubes (SWNT) and multi-walled nanotubes (MWNT). These cylindrical carbon molecules have novel properties that make them potentially useful in many nanotechnology applications, including electronics, optics and other fields of materials science.
Because of its unique symmetry the structure of a single-walled nanotube will strongly affect its electrical properties. For a nanotube's given chirality (n,m), if n = m then the nanotube is metallic; if n - m is a multiple of 3 then the nanotube is semiconducting with a very small band gap (if not the nanotube is a moderate semiconductor). In this image three nanotube configurations are shown (left image). Band structures (right image) computed using tight binding for (6,0) show it to be metallic;the configuration shown in (10,2)is semi-conducting and the illustration of the(10,10) nanotube is metallic. This is typical for(m,m)types.