Observations were made of a negative differential resistance behavior in the tunneling spectra recorded from hydrogen and nitrogen plasma-induced atomic defects on semiconducting single-walled carbon nanotubes. The negative differential resistance was observed only in the positive bias range of the spectra. This bias asymmetry, and the spectral shape in the negative differential resistance region, could be explained on the basis of a bias-dependent tunneling barrier height model. Within this model, the negative differential resistance behavior could be directly related to defect-induced sharp electronic states in the single-walled carbon nanotube band gap created at the defect sites.

Defect-Induced Negative Differential Resistance in Single-Walled Carbon Nanotubes. G.Buchs, P.Ruffieux, P.Gröning, O.Gröning: Applied Physics Letters, 2008, 93[7], 073115