In this paper, by using electrical junction in part of drain region which includes stepwise doping distribution,
a new structure is proposed for tunneling carbon nanotube field-effect transistors (T-CNTFETs).
The modified device consists of two parts in the drain region, a region without electrical junction and
a region having an electrical junction where the n-type impurity is entered stepwise along the drain
region. Electronic features of the modified device are simulated by the simultaneous solution of both
Schrodinger and Poisson equations in self-consistent routine. Simulation consequences demonstrate that
the proposed modifications reduce OFF state current and enhance the ON/OFF ratio in comparison with
the conventional structures. Moreover, delay time, the product of delay and power, and subthreshold
slope as important features of the T-CNTFET are enhanced. Also, to more assessment of the suggested
structure, variations of cut-off frequency parameters, including transconductance and gate capacitance
have been investigated.