Influence analysis of dielectric pocket on ambipolar behavior and high-frequency performance of dual material gate oxide stack -double gate Nano-Scale TFET

In this paper, a new Nano-Scale structure of dual material gate oxide stack-double gate TFET (DMGOS-DG TFET) with the inclusion of the dielectric pocket (DP) in the drain region is proposed. Hence the gate consists of three parts, named M1, M2, and M3 with work functions ϕM1, ϕM2, and ϕM3 respectively. The work function engineering with the gate oxide stack (SiO2 as the bottom layer and HfO2 as the top layer) improves ON current, leakage current, and ambipolar behavior. In addition, the dielectric pocket (DP) has been used in the drain region to achieve better ambipolar performance. Moreover, it is found that in comparison with the low-k DP (SiO2), the presence of the high-k DP (HfO2) provides a lower ambipolar current due to the greater depletion width in the drain region. Furthermore, the ambipolar behavior of the DP-DMGOS-DG TFET structure has been investigated by changing the length and thickness of the high-k DP. Finally, the comparative analysis of DMGOS-DGTFET and high-k DP-DMGOS-DG TFET on high-frequency performance reveals that DP inclusion reduces the gate-to-drain capacitance, which leads to the improved cut-off frequency.