A Tunnel Field Effect Transistor (TFET) structure is similar to a metal oxide semiconductor field effect transistor (MOSFET) structure and includes a source, a drain, and a channel coupled to a gate. TFETs are available in different forms, such as n type (nTFET) and p type (pTFET) devices. The drain current (Id) increases with increasing gate voltage (Vg) for an nTFET and increases with decreasing Vg for a pTFET. The nTFET switches on (“on state”) for a gate/source voltage (Vg) greater than the threshold voltage, while the pTFET switches on for a Vg less than the threshold voltage. The source in an nTFET is p doped while the drain is n doped and the source in a pTFET is n doped while the drain is p doped. The channel is undoped or less doped, in terms of doping concentration, than the source or drain.
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