Impact of Band-Tails on the Subthreshold Swing of III-V Tunnel Field-Effect Transistor

We present a simple model to evaluate the sharpness of the band edges for tunnel field-effect transistors (TFETs) by comparing the subthreshold swing and the conductance in the negative differential resistance region. This model is evaluated using experimental data from InAs/InGaAsSb/GaSb nanowire TFETs with the ability to reach a subthreshold swing well below the thermal limit. A device with the lowest subthreshold swing, 43 mV/decade at 0.1 V, exhibits also the sharpest band-edge decay parameter E
₀
of 43.5 mV although in most cases the S ≪ E
₀
. The model explains the observed temperature dependence of the subthreshold swing.