Representation of an engineered double-step structure SOI-TFET with linear doped channel for electrical performance improvement: a 2D numerical simulation study

Abstract

In this paper, a novel double-step (DS) structure tunnel field-effect transistor with a linear doping profile channel (DSS-LDC-TFET) is presented. The use of a step-shaped structure near the source/channel interface leads to the large tunneling junction area because the band-to-band tunneling of the carriers occurs perpendicularly along the conducting path in the channel. The step-shape of the channel/drain interface reduces the electric field distribution near the drain junction which helps to suppress the ambipolar behavior. Further, the DS structure of the body suppresses the ambipolar conduction due to increasing the effective length of channel area along the device. Therefore, the height of the steps in the proposed structure plays an important role in the device characteristics. The doping profile in the channel region is considered to be linear. The maximum value of the doping concentration is at the source side and linearly decreases to its minimum value along the x-axis. Numerical simulation results show that using the linear doping distribution at the channel improves device behavior through reducing the tunneling barrier width at the source/channel interface. The optimum length for the linear-doped part of the channel is selected to maximize the on-state current without degrading much the off-state current. Finally, the comparative study between DSS-LDC-TFET with the conventional silicon-on-insulator tunnel field-effect transistor is presented.