Suppression of Ambipolar Behavior and Simultaneous Improvement in RF Performance of Gate-Overlap Tunnel Field Effect Transistor (GOTFET) Devices

Abstract

This paper investigates a method to suppress the ambipolar current Iamb effectively, enhance the device performance with higher on current Ion, lower off current Ioff, lower inverse subthreshold slope SS and simultaneously improve the RF performance. Starting with a conventional double-gate TFET structure, the device optimization reported in this work has led to the gradual improvement in device performance in terms of higher Ion, lower Ioff, higher Ion/Ioff ratio and lower SS. The RF parameters of the optimized GOTFET, such as the mutual transconductance gm, gate-to-drain CGD, and gate-to-source CGS capacitances and unity-gain cut-off frequency fT are analyzed. We have optimized the tunnel FET device using the industry-standard synopsys® TCAD tools by studying the impact of various device parameters and dimensions on performance. We demonstrated that at high negative voltages, the proposed nGOTFET would completely suppress the ambipolar behavior of the device without deteriorating the device performance. We have compared the ambipolar current Iamb, Ioff, Ion, SS with 45 nm technology MOSFET and the TFETs reported earlier in literature. For the first time, we have proposed a GOTFET which completely suppresses the ambipolar current at high negative biases, without compromising the high Ion (1.04 mA/μ m) and low Ioff (0.27 pA/μ m) and low SS (32 mV/dec) at room temperature.