Abstract
Aluminium gallium nitride/gallium nitride (AlGaN/GaN)-based superlattice castellated field-effect transistors are a potential basis for high-power radiofrequency amplifiers and switches in future radars. The reliability of such devices, however, is not well understood. Here we report transistor latching in multichannel GaN transistors. At the latching condition, drain current sharply transits from an off-state value to a high on-state value with a slope less than 60 mV per decade. Current-voltage measurements, simulations and correlated electroluminescent emission at the latching condition indicate that triggering of fin-width-dependent localized impact ionization is responsible for the latching. This localization is attributed to the presence of fin-width variation due to variability in the fabrication process. The latching condition is reversible and non-degrading, and we show that it can lead to improvement in the transconductance characteristics of transistors, implying improved linearity and power in radiofrequency power amplifiers.