We conducted comprehensive direct current (DC) and small-signal radio frequency (RF) characterization on AlGaN/GaN high-electron-mobility transistors (HEMTs) from 25 to 500 °C to investigate temperature-dependent variations in key device performance metrics, such as transconductance (gm), maximum-to-minimum drain current ratio (Imax/Imin), current gain cutoff frequency (fT), maximum gain frequency (fmax), unilateral power gain, and maximum stable gain. We compared prototype 140 nm AlGaN/GaN HEMTs made with regrown Ohmic contacts with production 180 nm AlGaN/GaN HEMTs made with standard alloyed Ohmic contacts. Our findings indicate that irrespective of the type of technology, DC and RF performance parameters decline with increasing temperature. Specifically, for every 100 °C increase in temperature, fT, fmax, and gain decreased by 6–8 GHz, ∼17 GHz, and ∼1 dB, respectively. These measurements provide insights onto how these GaN-based RF devices can be used in extreme thermal environments.
Sarker et al. (Mon,) studied this question.