Currently aimed for the 5nm node, the tunnel field-effect transistor (TFET) is a steep sub-threshold slope transistor that can scale the supply voltages below 1 volt, and possibly as low as sub-0.5 volts. TFETs could appear in 2D and 3D configurations. They could be based on bulk CMOS or silicon-on-insulator (SOI) technology. The TFET is similar to today’s MOSFETs, but the TFET is actually a gated-diode that makes use of an electron tunneling technology. In theory, TFETs could switch on and off at lower voltages than current and future finFETs. The TFET operates in reverse bias. TFETs make use of band-to-band tunneling of electrons through a barrier, as opposed to flowing over a barrier as in MOSFETs.