Effects of Drain Doping Profile and Gate Structure on Ambipolar Current of TFET

In this paper, the effects of drain doping profile and gate structure on ambipolar behavior of tunnel field effect transistor (TFET) are investigated. The Gaussian doping drain region TFET (GD TFET) ambipolar current is lower than abrupt junction doping TFET. The influence of gate structure, oxide thickness (t
ox
) and channel thickness (t
si
) on the ambipolar current of GD TFET are studied by TCAD simulation. Compared with traditional TFET, GD TFET requires longer gate-on-drain overlap length (Lgd) to suppress ambipolar current, and it will be affected by t
ox
and t
si
. With the increase of gate underlap drain length (Lug), the ambipolar current of GD TFET decreases regardless of device parameters, which effectively suppresses the ambipolar behavior of TFET. When the Lug is 10 nm, the ambipolar current of GD TFET decreases from 10
^-9
A/μm of traditional TFET to 10
^-16
A/μm, and the subthreshold swing remains invariable in the on-state.