This study explores the performance optimization of charge plasma-assisted Ge/Si/GaAs Double-Gate (DG) Junctionless Tunnel Field-Effect Transistors (TFETs) and their homogeneous DG-JL-TFET counterparts, targeting ultra-low-power and high-frequency applications. By leveraging the unique material properties of germanium (Ge), silicon (Si), and gallium arsenide (GaAs), the design achieves superior performance: Ge, with its high electron mobility, serves as the source, Si- materials have moderate stability, functions as the channel and GaAs, recognized for its high-speed characteristics, is employed as the drain. The adoption of charge plasma technology eliminates the need for traditional doping, simplifying fabrication and mitigating dopant fluctuation issues. For the homogeneous structure, the device achieves an on-state current ( \(I_{\text {on}}\) ) of \(6.0 \times 10^{-3} \, \text {A}\) , with fixed off-state current ( \(I_{\text {off}}\) ) of 9.6 fA, resulting in an exceptional \(I_{\text {on}}/I_{\text {off}}\) ratio of \(6.2 \times 10^{11}\) . Additional performance metrics include threshold voltage ( \(V_t\) ) of 0.93 V, subthreshold swing (SS) of 52 mV/dec, transconductance ( \(g_m\) ) of \(3.4 \times 10^{-3} \, \text {S}\) , output conductance ( \(g_d\) ) of \(3.19 \times 10^{-9} \, \text {S}\) , cut-off frequency ( \(f_t\) ) of 374 GHz, and maximum oscillation frequency ( \(f_{\text {max}}\) ) of 738 GHz. The heterogeneous structure outperforms its homogeneous counterpart, achieving an \(I_{\text {on}}\) of \(6.3 \times 10^{-3} \, \text {A}\) (a \(5\%\) improvement), \(V_t\) of 0.4 V (a \(56.99\%\) reduction), and an SS of 24 mV/dec (a \(53.85\%\) improvement). Moreover, the transconductance ( \(g_m\) ) increases to \(4.5 \times 10^{-3} \, \text {S}\) (a \(32.35\%\) boost), while the ( \(f_t\) ) and ( \(f_{\text {max}}\) ) rise significantly to 795 GHz (a \(112.57\%\) improvement) and 838 GHz (a \(13.56\%\) improvement), respectively. These results highlight the heterogeneous Ge/Si/GaAs TFET as a highly promising solution for next-generation mixed-mode and ultra-low-power and high-frequency integrated circuit applications.
