Choking of electron flow: A mechanism of current saturation in field-effect transistors

Abstract

We describe a mechanism of the current saturation in a field-effect transistor (FET) caused by choking of electron flow. The choking occurs when the electron velocity at the drain side of the channel reaches the plasma-wave velocity. This effect is quite similar to the choking of a gas flow in a pipe. This mechanism is an alternative to the well-known mechanism of current saturation caused by the drift velocity saturation in the FET channel. We show that the choking mechanism may dominate in a submicrometer ${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As/GaAs FET at 10 K and low drain and gate bias voltages.