Reduced Miller Capacitance in U-Shaped Channel Tunneling FET by Introducing Heterogeneous Gate Dielectric

In this letter, a novel U-shaped channel tunneling FET (UTFET) with heterogeneous gate dielectric (HG-UTFET) is designed to reduce the Miller capacitance (C
_M
) and to improve the performance of TFET digital circuits. Because the HG-UTFET and UTFET have the same gate dielectric near the source region, these two devices nearly have the same on-state current. But due to the smaller gate-to-drain capacitance (C
_gd
) caused by the low-k gate dielectric near the drain region, the HG-UTFET has smaller C
_M
compared with UTFET, which will enhance the switching performance of digital circuits. The simulation results reveal that the overshoot/undershoot and rising/falling delay of the output signal in the HG-UTFET inverter are reduced a lot compared with the UTFET inverter. Results show that the C
_M
and falling delay of the HG-UTFET inverter are ~45.6% and ~30.7% less than that of the UTFET inverter, respectively. Therefore, by the application of HG-UTFET, the switching performance of inverter can be enhanced a lot.