Lateral NiO/AlN Heterojunction Rectifiers with Breakdown Voltage >11 kV

Lateral NiO/AIN heterojunction diodes (HJDs) with breakdown voltage up to 11.6 kV and Ni/Au/AlN Schottky barrier diodes (SBDs) with V B of 8.6 kV were fabricated on layers grown on sapphire substrates by metalorganic chemical vapor phase deposition. The power figure-of-merits V B 2 /R ON where R ON is the on-resistance were 0.31 MW·cm −2 for HJD and 0.16 MW·cm −2 for SBD. The lowest turn-on voltages were ∼2.03 and 1.91 V for HJDs and SBDs, respectively, with ON/OFF ratios up to 10 2 . The maximum field before breakdown was 0.45 MV·cm −1 in HJDs and 0.31 MV·cm −1 in SBDs. These correspond to <3% of the critical field in AlN of ∼15 MV·cm −1 . This work demonstrates there is still significant optimization to be done in the overall quality of the AlN, including purity, crystal perfection, and defect density to realize the potential of this material as an ultra-wide bandgap semiconductor for efficient multi-kV power switching applications. Our results also demonstrate the promise of NiO as a p-type conducting oxide for forming heterojunctions with AlN.