Investigations on Unclamped-Inductive-Switching Behaviors of p-GaN HEMTs at Cryogenic Temperature

In this paper, the unclamped-inductive switching (UIS) behaviors of GaN-based high electron mobility transistors with p-GaN cap (p-GaN HEMTs) at cryogenic temperature (CT) are investigated in details. Unlike the temperature-dependent avalanche process induced failure for Si-based MOSFETs, the withstanding behaviors of p-GaN HEMTs are not affected by temperature. With the help of TCAD simulations and experimental characterizations, the temperature-independent inverse piezoelectric effect induced by high electric field during UIS process is considered as the original failure inducement. Meanwhile, it is demonstrated that p-GaN HEMTs have higher robustness at extremely low temperature scene under repetitive UIS stress. After enduring 5M UIS stress cycles at CT, the threshold voltage (V
th
) only increases by 0.06 V and ON-state resistance (R
dson
) increases by 4 mΩ, implying higher device reliability at CT. In conclusion, compared with traditional Si-based devices, p-GaN HEMTs are more competitive in extremely low temperature scene.