All the above discussed results were calculated for a device with a CNT length
. In the case of ballistic transport the current is
independent of the device length, but in the presence of scattering
it decreases as the device length increases.
Fig. 5.25-a shows the ballisticity as a function of the CNT length in the presence
of elastic and inelastic electron-phonon interaction. An artificially
large value for the electron-phonon coupling strength and a small value
for the phonon energy is chosen to simulate the diffusive limit (see Fig. 5.25-b).
In this case, the current is expected to
be inversely proportional to the device length according to OHM's law.
5.5.3 Diffusive Limit
M. Pourfath: Numerical Study of Quantum Transport in Carbon Nanotube-Based Transistors