NiO/β-Ga₂O₃ heterojunction diodes with ultra-low leakage current below 10⁻¹⁰ A and high thermostability

The 10 nm p-NiO thin film is prepared by thermal oxidation of Ni on β-Ga₂O₃ to form NiO/β-Ga₂O₃ p–n heterojunction diodes (HJDs). The NiO/β-Ga₂O₃ HJDs exhibit excellent electrostatic properties, with a high breakdown voltage of 465 V, a specific on-resistance (R_on,sp) of 3.39 mΩ⋅cm², and a turn-on voltage (V_on) of 1.85 V, yielding a static Baliga's figure of merit (FOM) of 256 MW/cm². Also, the HJDs have a low turn-on voltage, which reduces conduction loss dramatically, and a rectification ratio of up to 10⁸. Meanwhile, the HJDs' reverse leakage current is essentially unaffected at temperatures below 170 °C, and their leakage level may be controlled below 10⁻¹⁰ A. This indicates that p-NiO/β-Ga₂O₃ HJDs with good thermal stability and high-temperature operating ability can be a good option for high-performance β-Ga₂O₃ power devices.