Breakdown up to 13.5 kV in NiO/β-Ga₂O₃ Vertical Heterojunction Rectifiers

Abstract Vertical heterojunction NiO/β n-Ga2O/n+ Ga2O3 rectifiers fabricated on 15 µm thick drift layers with carrier concentration 8.8 x1015 cm-3 and employing simple dual-layer PECVD SiNx/SiO2 edge termination demonstrate breakdown voltages (VB) up to 13.5 kV, on-voltage (VON) of ~2.2V and on-state resistance RON of 11.1-12 mΩ.cm2. The average breakdown field is ~9 MV. cm-1, within the reported theoretical value range from 8-15 MV.cm-1. The associated power figure-of-merit, VB2/RON is 15.2 GW·cm-2. By sharp contrast, Schottky rectifiers concurrently fabricated on the same drift layers had maximum VB of 2.9 kV, but lower VON of 0.71-0.75 V. Transmission electron microscopy showed an absence of lattice damage between the PECVD and sputtered films within the device and the underlying epitaxial Ga2O3. The key advances are thicker, lower doped drift layers and optimization of edge termination design and deposition processes.