Influence of Drain Doping Engineering on the Ambipolar Conduction and High-Frequency Performance of TFETs

In this paper, the effect of a proposed drain doping engineering on the ambipolar conduction and high-frequency performance of tunneling FETs (TFETs) is investigated using 2-D TCAD simulations. The proposed TFET structure is based on using a high-doped region above a low-doped region of the drain side. It is demonstrated that when splitting the drain into two regions, one with high doping above the other of low doping, the tunneling width at the channel-drain interface increases. This increase in the tunneling width causes an appreciable reduction of ambipolar current in the TFET. Moreover, high-frequency-figures of merit regarding the transconductance (g
_m
), source-to-gate and drain-to-gate capacitances, and unit-gain cutoff frequency (f
_T
) are analyzed. It is found that the combination of drain doping regions could enhance the high-frequency performance. Additionally, the proposed technique does not deteriorate the ON-current levels.