Effect of a gate bias voltage on quantum dots in single-walled carbon nanotubes

In this study, the electrical transport properties of single-walled carbon nanotubes with Co contacts were investigated. The electrical transport measurements revealed an n-type field effect. Irregular Coulomb diamond features and beat patterns, which suggest the formation of multiple dots in the tubes, were observed and confirmed by the temperature dependence of Coulomb oscillations. Upon increasing the gate bias voltage, the multi-dots were transformed into single dots. Such experimental observations can be explained by the variation of electrochemical potential along the single-walled nanotube, which modulates the height of local barriers in the nanotubes.