Coherent transport between two interface states in single-walled carbon nanotube quantum dots

The resonance tunnelling of states at two interfaces are investigated through the three models of two-terminated carbon nanotube heterojunctions: (5, 5)/(10, 0)/(5, 5), (9, 0)/(10, 0)/(9, 0) and (5, 5)/(10, 0)/(9, 0). In (5, 5)/(10, 0)/(5, 5) CNQD, we observed the existence of interface states in LDOS, and the resonant tunnelling peak at the position of interface states also emergent in quantum conductance. With the increase of QDs size, the resonant tunnelling peak gradually disappears. Comparing their quantum conductance for different sizes, when the size of the (5, 5)/(10, 0)/(5, 5) model is larger than 23 layers, there is not a quantum conductance peak at −0.26 eV. Therefore, the largest size for resonant tunnelling occurring between two interface states in (5, 5)/(10, 0)/(5, 5) is about 23 layers (about 45 Å).