Recent study on on-state breakdown modeling of pHEMTs

Traditionally, the on-state breakdown of pHEMTs is attributed to impact ionization and thermal breakdown under high Vd stress. Nonetheless, neither of these hypotheses perfectly explains all observations, including but not limited to when on-state breakdown happens and how it happens in devices with various structures. A systematic study on the on-state breakdown of pHEMTS carried out by our group recently reveals strong correlation between the adjusted input power and the burnout locus of devices. We further conclude that on-state breakdown happens mainly because the temperature of a certain spot in the channel exceeds a critical value, and that this hot pot, usually emerging beneath the drain-side end of the gate electrode, is the result of the unevenly distributed electric field in the channel of the pHEMT. We thereby developed a simple model which sheds some light on the physics mechanism behind on-state breakdown of pHEMTs and is capable of accurately predicting the corresponding burnout voltage for different devices under operating various operation conditions.