Structural determination of single-walled carbon nanotube with an intramolecular junction and its electrical transport property

By utilizing a novel design of an electronic device with microfabricated through-etched slits for transmission electron microscopy (TEM), single-walled carbon nanotubes (SWNTs) suspended over two metal electrodes were successfully characterized. A semiconducting-semiconducting intramolecular junction (IMJ) was found from a change in chirality along the tube. Interestingly non-linear current-voltage characteristic was found despite almost negligible difference in the band-gap energy (13 meV). The non-linear electrical transport property can be caused by asymmetric defect states positioned in the band-gap of two semiconducting tubes, which make one as donor (similar to a p-type semiconductor) and the other as acceptor (similar to n-type semiconductor). The strain by deformation along the tube can also cause the electrical non-linearity.