  In this work, we studied the gate breakdown mechanisms of p-GaN gate
AlGaN/GaN HEMTs by a novel multiple-gate-sweep-based method. For the first
time, three different breakdown mechanisms were observed and identified
separately in the same devices: the metal/p-GaN junction breakdown, the
p-GaN/AlGaN/GaN junction breakdown, and the passivation related breakdown. This
method is an effective method to determine the breakdown mechanisms. The
different BD mechanisms were further confirmed by scanning electron microscopy
(SEM). Finally, the temperature dependences of the three BD mechanisms were
measured and compared. This analysis method was also employed in the devices
with a different passivation material and showed its applicability.
