VT-Modulation of Planar Tunnel Field-Effect Transistors with Ground-Plane under Ultrathin Body and Bottom Oxide

Control of threshold voltage (V_T) by ground-plane (GP) technique for planar tunnel fieldeffect transistor (TFET) is studied for the first time using TCAD simulation method. Although GP technique appears to be similarly useful for the TFET as for the metal-oxide-semiconductor field-effect transistor (MOSFET), some unique behaviors such as the small controllability under weak ground doping and dependence on the dopant polarity are also observed. For V_T-modulation larger than 100 mV, heavy ground doping over 1×1020 cm^-3 or back biasing scheme is preferred in case of TFETs. Polarity dependence is explained with a mechanism similar to the punch-through of MOSFETs. In spite of some minor differences, this result shows that both MOSFETs and TFETs can share common V_T-control scheme when these devices are co-integrated.