A design of improved nanoscale U-Shaped TFET by energy band modification for high performance digital and analog/RF applications

In this study, a new nanoscale U-shaped tunnel field-effect transistor (US TFET) structure is proposed. In order to start the design process, the drain region of the conventional US TFET is divided into two distinct parts with N+ and N- doping which is named the drain doping engineering (DDE). It is considered that the tunneling barrier at the channel-drain junction is increased and consequently the ambipolar current is decreased considerably. To continue the design process, the dual work function (DW) in the DDE-US TFET has been used to ameliorate the DC characteristics and the cutoff frequency. Moreover, we have used the metal implant (MI) in the source-side oxide of DDE-DW-US TFET as a technique to improve the device for high-frequency and low-power applications. The 2 -D TCAD simulation results not only indicate the superiority of the proposed structure (DDE-DW-MI-US TFET) compared to others in terms of the highfrequency performance, but also illustrate the improvement of the DC parameters. Finally, the proposed device has been investigated by increasing the length of implanted metal in the source-side oxide. It is found that selecting the appropriate length contributes significantly to improve high-frequency performance.