Threshold voltage engineering via diode-embedded p-GaN gate HEMTs

In this work, enhancement-mode (E-mode) p-GaN/AlGaN/GaN high-electron-mobility transistors (HEMTs) with monolithically embedded gate diodes are investigated to explore the use of embedded diode width as a design parameter for threshold-voltage engineering. The embedded diode geometry modulates the electrostatic potential within the gate stack, thereby tuning the threshold voltage. A wide threshold-voltage tuning range of 1.45–3.3 V was achieved, where 1.45 V corresponds to the reference device without an embedded diode and 3.3 V corresponds to the device with a diode-to-HEMT channel ratio of 0.1. In addition, the diode-embedded structure exhibits improved forward gate breakdown voltage while maintaining comparable on-resistance and off-state breakdown voltage. Pulsed bias measurements reveal that smaller diode widths effectively suppress negative threshold-voltage shifts, indicating enhanced dynamic gate stability. These results demonstrate that monolithically embedded gate diodes provide an effective and scalable approach for threshold-voltage engineering and reliability enhancement in E-mode GaN HEMTs for power-switching applications.