High-performance vertical <i>β</i> -Ga2O3 Schottky barrier diodes utilizing sputtered p-NiO double mesa junction termination extension

Effective management of peak electric fields at the electrode edge poses a critical challenge in realizing the full potential of ultra-wide bandgap β-Ga2O3 power devices. In this work, we report on the fabrication and characterization of vertical β-Ga2O3 Schottky barrier diodes (SBDs) employing a termination structure designated as double-mesa junction termination extension (DMJTE), which is applied to vertical β-Ga2O3 devices for the first time. This design integrates a hierarchical dual-mesa architecture with a sputtered p-type NiO layer to provide a synergistic JTE-induced lateral depletion effect. The mesa geometry, comprising a 300 nm shallow step and a 1.5 μm deep trench, both formed using a BCl3/Ar inductively coupled plasma etching process. Electrical characterization reveals that the DMJTE-SBD achieves a breakdown voltage (Vbr) of 2810 V. This breakdown voltage represents a substantial improvement over 590 V measured for the reference planar SBD (Ref-SBD) and 1530 V obtained for the single-mesa SBD with JTE (SMJTE-SBD). With a specific on-resistance of 6.9 mΩ cm2, the proposed DMJTE-SBD demonstrates a high power figure of merit of 1.14 GW/cm2. TCAD simulations validate that the DMJTE topology effectively smooths the potential gradient and displaces the peak electric field away from the anode edge.