Investigating Forward Gate ESD Mechanism of Schottky-Type p-GaN Gate HEMTs Using a SiC-Based High-Speed Pulsed I-V Test System

The forward gate human-body-model (HBM) electrostatic discharge (ESD) robustness and mechanisms of the Schottky-type p-GaN gate HEMTs are investigated. Unexpectedly, the transient forward gate leakage current ( IG ) is high during appreciable, yet non-destructive, discharge events. To characterize the elevated IG more comprehensively, we use SiC MOSFETs to devise a new pulsed I-V test system. This system is capable of generating voltage pulses with a rise time of ≤10 ns and width of <100 ns, and a maximum pulse current of 26 A. The pulsed IG - VG (gate voltage) characteristics’ temperature and time dependencies suggest that the high transient IG is primarily governed by electron thermionic emission across the AlGaN barrier. This emission is stimulated by the dynamic capacitive VG division within the two back-to-back junctions of the p-GaN gate stack rather than by the resistive VG division observed in the steady-state conditions.