SWCNT single-walled carbon semiconducting

High-field transport properties of single wall carbon nanotubes (SWCNT) are analyzed on the basis of phonon-assisted tunneling (PhAT) model. This model enables to explain not only temperature-dependent current-voltage characteristics of SWCNT, but also the crossover from a semiconducting-like temperature dependence conductivity to a metallic-like one as temperature is increased. 

It is well known that the percolation threshold is strongly dependent on the aspect ratio. One-dimensional (ID) nanostructures, such as nanowires, nanotubes, and nanoribbons, have geometries that are favorable for the maintenance of connectivity at low content of active materials. Carbon nanotubes (CNTs) are a good representative example. Electrical percolation can be achieved in polymer composites with well-dispersed single-walled carbon nanotubes (SWCNTs) at levels as low as 0.03 wt% [69]. Recently, it has been reported that the formation of semiconducting nanofibers facilitates percolation in semiconducting/insulating polymer blends. 

Single nanostructures pump probe microscopy experiments revealed energy relaxation pathways that are obscured by ensemble averaging. For example, understanding of the intrinsic optical properties of single wall carbon nanotubes (SWCNTs) has been previously hindered primarily by the broad distribution of semiconducting and metallic nanotube types in as-synthesized... 

CNTs are commonly classified into single-waUed (SWCNTs) and multi-walled (MWCNTs) nanotubes [28]. SWCNTs consist of a single graphene layer rolled up into a hollow cylinder and are either metallic or semiconducting, whereas MWCNTs are comprised of two, three, or more concentrically arranged cylinders and exhibit only metallic character. Double-wall carbon nanotubes (DWCNTs) are the most basic members of the MWCNT family. The special role of DWCNTs should be emphasized, as they are the link between SWCNTs and the more complex MWCNTs and, therefore, of great interest for a fundamental understanding of these novel nanostructures. 

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