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 ( ${I}_{\text {G}}$ ) is high during appreciable, yet non-destructive, discharge events. To characterize the elevated ${I}_{\text {G}}$ 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 $\le 10$ ns and width of <100 ns, and a maximum pulse current of 26 A. The pulsed ${I}_{\text {G}}$ - $V_{\text {G}}$ (gate voltage) characteristics’ temperature and time dependencies suggest that the high transient ${I}_{\text {G}}$ is primarily governed by electron thermionic emission across the AlGaN barrier. This emission is stimulated by the dynamic capacitive ${V}_{\text {G}}$ division within the two back-to-back junctions of the p-GaN gate stack rather than by the resistive ${V}_{\text {G}}$ division observed in the steady-state conditions.