Complementary Germanium Electron–Hole Bilayer Tunnel FET for Sub-0.5-V Operation

In this letter, we present a novel device, the germanium electron-hole (EH) bilayer tunnel field-effect transistor, which exploits carrier tunneling through a bias-induced EH bilayer. The proposed architecture provides a quasi-ideal alignment between the tunneling path and the electric field controlled by the gate. The device principle and performances are studied by 2-D numerical simulations. This device allows interesting features in terms of low operating voltage (<; 0.5 V), due to its super-steep subthreshold slope (SS_AVG ~ 13 mV/dec over six decades of current), I_ON/I_OFF ratio of ~ 10⁹, and drive current of I_ON ~ 10 μA/μm at V_DD = 0.5 V. The same structure with symmetric voltages can be used to achieve a p-type device with I_ON and I_OFF levels comparable to the n-type, which enables a straightforward implementation of complementary logic that could theoretically reach a maximum operating frequency of 1.39 GHz when V_DD = 0.25 V.