Hot-Electron Hardening in GaN-Based Power Devices by Selective p-GaN Gate Epitaxy

A selective gate epitaxy strategy is proposed for p-GaN gate formation in enhancement-mode high-electron-mobility transistors (HEMTs) to enhance robustness against hot-electron effects. This approach avoids p-GaN growth and etching processes in the access region, preserving the high-quality as-grown barrier layer. Compared to the conventional p-GaN gate HEMTs, devices with selective epitaxial gate demonstrate$1.5\times $higher drain breakdown voltage at${V}_{\text {GS}}$of 6 V and significantly reducedon-resistance (${R}_{\text {on}}\text {)}$degradation during long-term semi-on stress with${V}_{\text {DS}}$ranging from 100 to 400 V. The selective p-GaN gate epitaxy is also compatible with the gate recess process, maintaining normally-off operation with thick AlGaN barriers, achieving furtheron-resistance reduction.