A Novel PNPN-Like Z-Shaped Tunnel Field- Effect Transistor With Improved Ambipolar Behavior and RF Performance

To suppress the ambipolar behavior and improve RF performance in tunnel field-effect transistors (TFETs), a Z-shaped (ZS)-TFET is proposed. The proposed ZS-TFET is more scalable than other vertical band-to-band-based TFETs and provides higher ON-state current (ION), larger ON/OFF current ratio (ION/IOFF) and lower subthreshold swing compared to conventionalTFETs. These advantages stem from the tunneling junction in the ZS-TFET being perpendicular to the channel direction, which facilitates the formation of a relatively large tunneling junction area. The ZS body makes use of both vertical and horizontal fields while suppressing the lateral parasitic tunneling current. In addition, by using a ZS gate in the proposed device, the energy band diagram near the source is modulated to create an N
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source pocket which creates a downward band bending of the potential, similar to PNPN-like structures. Finally, the proposed structure significantly improves the analog/RF figure-of-merit.