A Novel Step-shaped Gate Tunnel FET with Low Ambipolar Current

In this paper, a novel TFET architecture named the step-shaped gate TFET (SSG-TFET) has been proposed for the suppression of the ambipolar current. By adjusting the energy band, the SSG-TFET can evidently reduce the ambipolar current. We compare the proposed SSG-TFET with the conventional DGTFET, gate overlap on drain TFET (OGTFET) and gate underlap TFET (SG-TFET) by using TCAD tool Sentaurus and found that the SSG-TFET can evidently suppress the ambipolar current. To be specific, the ambipolar current of the SSG-TFET decreases 7 orders of magnitude from 10$^{-9} {A}/\mu$m for conventional TFET to 10$^{-16}{A}/\mu$m atVgs = -1.5 V. For the proposed SSG-TFET, we have found that there exists an optimal right gate dielectric thickness t oxdb with minimum ambipolar current of SSG-TFET. Moreover, we investigate the influence of the Si body thickness t si , the length of the oxide layer exceeds the interface of channel and the drain on the optimal thickness of the right gate dielectric of the SSG-TFET. The simulation results show that the optimal oxide layer thickness t oxdb decreases with the increase of $t_{s}$, and t oxdb increases with the increase length of L un and L ov , but when L ov $\gt 40$ nm, t oxdb remains the same. The proposed SSG-TFET with low ambipolar current can be used for the ultra-low power integrated circuit applications.