Vertical GaN Schottky Barrier Diode With Hybrid P-NiO Junction Termination Extension

Abstract Selective-area p-type doping has been regarded as one of the primary challenges in vertical GaN junction-based power devices. Nickel oxide (NiO), serving as a natural p-type semiconductor without the requirement for sophisticated activation and enabling adjustable charge concentration, is potentially feasible to form pn hetero-junction in GaN power devices. In this work, a vertical GaN Schottky barrier diode (SBD) featuring hybrid p-NiO junction termination extension (HP-JTE) with fluorine (F)-implanted buried layer (FIBL) has been demonstrated. With FIBL incorporated underneath p-NiO in the termination region, the reverse leakage current can be effectively reduced by approximately 3 orders of magnitude. By virtue of photon emission microscopy measurements, it has also been verified that the light emission and leakage current through p-NiO termination region can be effectively suppressed by FIBL. Thanks to the HP-JTE structure as well as the nearly ideal Schottky interface, the vertical GaN SBD exhibits a high current swing of $\sim 10^{13}$ , a low ideality factor of $\sim 1.02$ , a low differential $R_{O N}$ of $\sim 0.89 \mathrm{~m} \Omega \cdot \mathrm{cm}^2$ , a low forward voltage drop of $\sim 0.8 \mathrm{~V}$ (defined at $100 \mathrm{~A} / \mathrm{cm}^2$ ), and a breakdown voltage of $\sim 780 \mathrm{~V}$ (defined at $0.1 \mathrm{~A} / \mathrm{cm}^2$ ). The characterizations and findings in this work can provide valuable insights into the p-NiO/GaN hetero-junction-based power devices.