High-performance <b> <i>β</i> </b> -Ga2O3 vertical diodes integrating metal-interlayer-semiconductor architecture and mesa termination

In this Letter, we report on high-performance β-Ga2O3 metal-interlayer-semiconductor (MIS) diodes featuring anode self-aligned mesa terminations and ultra-thin NiO as interlayers. The polycrystalline NiO interlayer was formed by thermal oxidation of a 5-nm Ni film deposited by e-beam evaporation and the mesa termination was fabricated by inductively coupled plasma etching. High-resolution transmission electron microscopy revealed a polycrystalline structure of the NiO and a perpendicular sidewall angle of approximately 84.6° at the mesa region. The 40-μm-radius mesa metal-interlayer-semiconductor Schottky barrier diodes achieves a low turn-on voltage of 1 V and a high breakdown voltage of 2.45 kV, while maintaining a decent specific on-resistance of 4.2 mΩ·cm2, yielding a power figure of merit of 1.43 GW/cm2, which is one of the highest among those reported state-of-the-art Ga2O3 MIS and mesa-termination diodes. Additionally, high on/off ratio of 1011, negligible C–V and I–V hysteresis curves, ideality factor of 1.2, and subthreshold swing of 74 mV/dec are demonstrated, all attributable to the well-defined NiO/Ga2O3 interface and the high crystal quality. The fabricated β-Ga2O3 MIS diodes with mesa termination show good switching performance, further promoting Ga2O3 technology for next-generation power electronics.