摘要
This paper investigates gate-to-source (G-S) electrostatic-discharge (ESD) robustness in 650-V p-GaN Schottky-gate enhancement-mode (E-mode) power HEMTs. For forward G-S ESD, epitaxial splits including top spacer (TS) and bottom spacer (BS) with varying Al composition were fabricated and evaluated. Transmission-line-pulse (TLP) measurements reveal that the forward G-S ESD capability strongly depends on the BS, with increasing Al composition significantly enhancing the forward TLP current. In particular, introducing an AlN BS increases the forward TLP current by approximately 14 times compared with the BS-free structure, whereas the TS exhibits a comparatively minor impact. TCAD simulations and failure analysis indicate that the AlN BS effectively mitigates current crowding beneath the gate, consistent with the measured ESD improvement. For reverse G-S ESD, a proposed source-connected secondary field-plate (FP2) structure combined with reduced gate-to-source spacing (L gs ) enhances the TLP current capability, achieving robustness up to JEDEC HBM Class 1C for a device with R on = 606 mΩ. The proposed solution introduces internal coupling capacitance without additional area penalty, strengthening transient discharge capability while reducing the channel depletion width and increasing the channel depletion capacitance.