The application of single-walled carbon nanotubes as the high performance electronic devices is expected, because the nanotubes are exceptional ballistic conductors. However, electronic current observed experimentally is saturated due to electron backscattering by phonon and Schottky barrier. In order to improve the performance of carbon nanotube devices, it is important to understand the effect of such scattering on transport properties.
We investigated the conductance and the mobility of the single-walled carbon nanotube field effect transistors (FETs) with electron-phonon coupling using the time-dependent wave-packet under a tight-binding approximation [1].
First, we calculated the conductance of the metallic carbon nanotubes with electron-phonon coupling. The phonon scattering largely decreases the conductance at Fermi energy. Then, we investigated the mobility of 1-micron semiconducting carbon nanotube FET without electron-phonon coupling. The mobility increases in proportion to the system length. On the other hand, the mobility decreases when the applied gate voltage becomes larger. Finally, we added the effect of electron-phonon coupling to the carbon nanotube FETs. We found that the mobility of the carbon nanotube FET is decided by only the Schottky barrier. Our calculation results show that the contacts to electrodes should be improved in order to realize the high performance carbon nanotube devices. In the presentation, we discuss the detail of above calculation results.
[1] S.Roche et al., Phys. Rev. Lett. 95 (2005) 076803
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