Evaluation of radio-frequency performance of gate-all-around ge/gaas heterojunction tunneling field-effect transistor with hetero-gate-dielectric by mixed-mode simulation

In this work, the frequency response of gate-all-around (GAA) Ge/GaAs heterojunction tunneling field-effect transistor (TFET) with hetero-gate-dielectric (HGD) and pnpn channel doping profile has been analysed by technology computer-aided design (TCAD) device-circuit mixed-mode simulations, with comparison studies among ppn, pnpn, and HGD pnpn TFET devices. By recursive tracing of voltage transfer curves (VTCs) of a common-source (CS) amplifier based on the HGD pnpn TFET, the operation point (Q-point) was obtained at V_DS = 1 V, where the maximum available output swing was acquired without waveform distortion. The slope of VTC of the amplifier was 9.21 V/V (19.4 dB), which mainly resulted from the ponderable direct-current (DC) characteristics of HGD pnpn TFET. Along with the DC performances, frequency response with a small-signal voltage of 10 mV has been closely investigated in terms of voltage gain (A_v), unit-gain frequency (f_unity), and cut-off frequency (f_T). The Ge/GaAs HGD pnpn TFET demonstrated A_v = 19.4 dB, f_unity = 10 THz, f_T = 0.487 THz and f_max = 18THz.