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 high-frequency 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.