2.7-kV CuCrO2/Ga2O3 heterojunction diode with stepped-mesa termination and on-state electrical stress reliability

In this work, we report vertical CuCrO2/β-Ga2O3 p–n heterojunction diodes (HJDs) incorporating a stepped-mesa termination for enhanced blocking performance and robust on-state reliability. The optimized HJD achieves a breakdown voltage of 2.71 kV with a specific on-resistance of 5.84 mΩ cm2, corresponding to a power figure of merit of 1.3 GW/cm2. TCAD simulations reveal that the stepped-mesa structure effectively suppresses electric-field crowding at the termination edge, accounting for the improved blocking capability. The on-state stability is further evaluated using a measurement-stress-measurement protocol under both constant-voltage and constant-current stress conditions. The HJD exhibits an essentially unchanged turn-on voltage and a minor increase in dynamic on-resistance, with the stress-induced variation being largely reversible after stress removal. Temperature-dependent reverse-current analysis suggests that the high-field leakage is governed by the trap-assisted Poole–Frenkel emission, yielding a trap barrier height of ∼0.35 eV. By correlating the recoverable stress response with the leakage-mechanism analysis, the stress-induced electrical variation is mainly associated with reversible electron capture and emission in preexisting trap states. This work demonstrates that stepped-mesa-terminated CuCrO2/β-Ga2O3 HJDs provide a promising route toward reliable kilovolt-class ultra-wide-bandgap power rectifiers.