Analytical relationship between subthreshold swing of thermionic and tunnelling currents

An analytical relationship between the subthreshold swing of the thermionic current and the tunnelling current is derived for double-gate metal-oxide semiconductor field-effect transistors (MOSFETs), based on the Wentzel-Kramers-Brillouin approximation. This formula allows predicting the behaviour of an ultimately scaled MOSFET in the subthreshold regime, as well as the performance of III-V devices.