Mixed-Mode Circuit Analysis of Negative Capacitance Heterostructure Nanotube TFETs for Analog On-Chip Applications

This work presents a mixed-mode circuit analysis of a negative-capacitance heterostructure nanotube tunnel field-effect transistor (NC-HNT-TFET) using Silvaco ATLAS TCAD for analog-on-chip applications. The proposed device achieves a subthreshold swing (SS) of 20.2 mV/dec, a transconductance-to-current ratio (gm/ID) superior to that of a conventional Gate-All-Around (GAA) architecture, and a significantly higher intrinsic gain than MOSFET-based amplifiers, owing to enhanced drain resistance (ro). A complementary TFET common-source (CS) amplifier demonstrates a low-frequency voltage gain of 15 dB, a 3 dB and cutoff near 310 GHz, and two-pole system behaviour consistent with the extracted transfer function. The heterostructure employs a Ge/AlGaAs heterostructure with a HfO2 gate dielectric and a ferroelectric (FE) layer modelled using the Landau–Khalatnikov (LK) equation. Stability and non-hysteretic operation are confirmed through capacitance-matching analysis. The extracted RF figures of merit, cutoff frequency (fT) of 7.2 THz and maximum oscillation frequency (fmax) of 11.3 THz, are obtained by extrapolation of Y-parameter-based current-gain and unilateral-power-gain roll-offs, and are physically justified by the high tunnelling-enhanced gm and the ultra-thin ferroelectric capacitance. These results demonstrate strong potential for ultra-high-frequency analog front-end and system-on-chip integration.