Origin of Transconductance roll-off in mmWave AlGaN/GaN HEMTs

Paper in proceeding, 2023

Transconductance roll-off at high gate bias is an issue in mmWave AlGaN/GaN HEMTs, resulting in reduction of current gain cut-off frequency, fT and degradation in linearity. In this work, the cause of this effect is investigated by comparing competing source starvation and hot phonon scattering models in TCAD simulations. Simulation of a GaN HEMT with a 100 nm gate length and recessed contact suggests that the device characteristics could be better explained by the source starvation model. This work highlights the importance of including source starvation effects in the design of device and optimization of RF device characteristics.