Investigation of False Turn-On Behavior of Schottky P-Gan HEMT in Bridge-Leg Circuit over −55 °C - 150 °C Operating Temperature Range

The false turn-ON issue of 650 V commercial Schottky p-GaN high-electron mobility transistors (HEMTs) is evaluated under the hard switching double pulse testing mode and show strong dependency on the temperature conditions. The study firstly investigates the negative threshold voltage shift phenomenon in these devices, particularly under varying temperatures. A customized double-pulse tester circuit with bridge-leg configuration is then built to evaluate the false turn-ON problem over -55 degrees C - 150 degrees C operating temperature range. When the high-side transistor is turned ON, the fast switching exerts a large overshoot current I-D into the drain of the low-side device. The overshoot current consists of the displacement current that flows into C-OSS of the transistor and the current flowing through the channel due to false turn-ON of the device. As an indicator of the false turn-ON phenomenon, the peak value of overshoot current exhibits a 0.9 A difference comparing to the pure displacement current when dV/dt is 30 V/ns. Furthermore, the study establishes the occurrence of premature false turn-ON at cryogenic temperatures, underscoring the heightened vulnerability of Schottky p-GaN HEMTs to false triggering in low-temperature environments.