Design of a β-Ga2O3 Schottky Barrier Diode With p-Type III-Nitride Guard Ring for Enhanced Breakdown

This work presents the electrostatic analysis of a novel Ga₂O₃ vertical Schottky diode with three different guard ring (GR) configurations to reduce the peak electric field at the metal edges. Highly doped p-type GaN, p-type nonpolar AlGaN, and polarization-doped graded p-AlGaN are simulated and analyzed as the GR material, which forms a heterojunction with the Ga₂O₃ drift layer. GR with nonpolar graded p-AlGaN with a bandgap larger than Ga₂O₃ is found to show the best performance in terms of screening the electric field at the metal edges. The proposed GR configuration is also compared with a reported Ga₂O₃ Schottky diode with no GR and a structure with high-resistive nitrogen-doped GR. The optimized design is predicted to have a breakdown voltage as high as 6.2 kV and a specific ON-resistance of 3.55 mΩ-cm², which leads to an excellent power figure of merit of 10.8 GW/cm².