High-performance vertical GaN PN diodes utilizing a peripheral Schottky contact

This study proposes and demonstrates a facile edge termination method for vertical GaN PN diodes (PNDs) using a Schottky contact ring (SCR) to modulate the internal electric-field distribution. While vertical GaN power devices offer superior power density over lateral configurations, they suffer from premature breakdown due to electric-field crowding at the anode and mesa edges. In this work, TCAD simulations showed that integrating an SCR at the p-GaN periphery effectively smooths equipotential lines and alleviates localized field concentration. Experimentally, PNDs were fabricated with an ohmic anode and a Cr-based SCR, yielding an effective Schottky barrier height of 0.97 eV. The PND with SCR exhibited stable forward operation up to a high current density of 2 kA/cm². Furthermore, the structure achieved a significant enhancement in the reverse breakdown voltage, reaching 420 V compared to 380 V for the reference PND, consistent with simulation results. These findings demonstrate that the SCR-integrated design provides a robust, low-complexity alternative to conventional edge-termination techniques, offering a practical pathway to high-performance vertical GaN-based power electronics.