Transient study of self-heating effects in AlGaN/GaN HFETs: Consequence of carrier velocities, temperature, and device performance

GaN transistors offer a unique combination of high speed and high power. Devices capable of operating at close to 180 GHz can also be biased so that each electron may emit up to 100 phonons as it transits from source to drain. Therefore, strong heating effects in GaN transistors are expected. In this article, we present a time dependent model to examine current, power and temperature in pulsed and direct current conditions. The studies show that self-heating effects are significant even for very short pulse widths (∼ a few nanoseconds). The results explain part of the reasons for the low velocity observed in the short pulse measurements. Our calculations also suggest that the device performance could improve more than 30% if we can efficiently remove the self-heating effects.