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Low-damage, low-temperature, and easy-to-implement hydrogen-plasma-based termination is attractive for fabricating implantation- and etching-free GaN power p–n diodes. This work investigates in detail the hydrogenation process and unveils the critical role of thermal annealing. A subsequent thermal annealing is key to thermally driving down hydrogen to fully hydrogenate p-GaN to form the termination. The devices showed a specific on-resistance of 0.4 mΩ cm2 and a breakdown voltage (BV) of ∼1.4 kV. They also exhibited improved BV compared with mesa-etched devices. High temperature performance was also investigated. These results can serve as important references for future developments of GaN power electronics. [ABSTRACT FROM AUTHOR]

We report nonpolar vertical GaN-on-GaN p–n diodes grown on m-plane free-standing substrates. Cathodoluminescence measurements showed that the nonpolar p-GaN had a high quality with very few deep-level states. The device exhibited good rectifying behaviors with a turn-on voltage of 4.0 V, on-resistance of 2.3 mΩ·cm2, and high on/off ratio of 1010. The reverse current leakage was described by a trap-assisted space-charge-limited current conduction mechanism. The critical electrical field was calculated to be 2.0 MV/cm without field plates or edge termination. These results pave the way for development of novel nonpolar power electronics and polarization-engineering-related advanced power devices. [ABSTRACT FROM AUTHOR]