In this paper we have simulated electron phonon scattering in a SWCNT by solving Boltzmann equation. We have extracted electric current of a CNTFET by using a new consideration of Fermi level moderation. Finally we have reported a mechanism which moderate Fermi level in a CNT under an applied electric field. Results show Fermi level increase linearly respects to electric field and the slope of this line is proportionate to CNT diameter.
