>3kV NiO/Ga₂O₃ Heterojunction Diodes With Space-Modulated Junction Termination Extension and Sub-1V Turn-On

This work demonstrates high-performance vertical NiO/Ga₂O₃ heterojunction diodes (HJDs) with a 2-step space-modulated junction termination extension. Distinct from the current state-of-the-art Ga₂O₃ HJDs, we achieve breakdown voltage exceeding 3 kV with a low turn on voltage (V_ON) of 0.8V, estimated at a forward current density (I_F) of 1 A-cm^-2. The measured devices exhibit excellent turn-on characteristics achieving 100 A-cm^-2 current density at a forward bias of 1.5V along with a low differential specific on-resistance (Ron,sp) of 4.4 mΩ-cm². The SM-JTE was realized using concentric NiO rings with varying widths and spacing that approximates a gradual reduction in JTE charge. The unipolar figure of merit (FOM) calculated exceeds 2 GW-cm² and is among the best reported for devices with a sub-1V turn-on. The fabricated devices also displayed minimal change in forward I-V characteristics post reverse bias stress of 3 kV applied during breakdown voltage testing.