Electrical Degradation of InAlN/GaN HEMTs Operating Under ON Conditions

The degradation of InAlN/GaN high-electron-mobility transistors (HEMTs) for millimeter-wave applications has been examined under on conditions. Two dominant permanent degradation mechanisms have been identified as well as two trapping mechanisms which affect the device characteristics in different ways. Under high-voltage, low-current stress conditions, we have observed permanent enhancement in the maximum drain current IDmax that arises from a negative shift in threshold voltage VT. We attribute this mechanism to depassivation of hydrogenated defects. Under the same stress conditions, there is prominent and reversible hot-electron trapping on the drain side of the device that brings IDmax down and increases the drain resistance. Under low-voltage high-current stress conditions, there is a visible permanent reduction in IDmax and a positive shift in VT. This is also the signature of-high temperature stress under unbiased conditions and is attributed to gate sinking.