1-kV AlGaN/GaN schottky barrier diode on a Si substrate by oxidizing the Schottky contact

High-voltage AlGaN/GaN Schottky barrier diodes (SBDs) are fabricated on Si substrates by oxidizing Ni-based Schottky contacts. Oxidation successfully suppresses the isolation-leakage current by about three orders of magnitude because GaO x and AlO x formed at the mesa-etched and active regions with suppressing surface conduction. The oxidation decreased the reverse leakage current of the devices. The reverse leakage current of the oxidized device was less than 10 mA/cm 2 at −100 V. The Schottky contact was changed from a Ni/Au to a Ni/Ni-Au complex/Au/NiO x structure after the oxidation. Ni was diffused into AlGaN during the oxidation, which improved the Schottky interface. When the anode-cathode distance (D AC ) was 20 µm, the forward voltage drop, the on-resistance, and the breakdown voltage of the oxidized device were 1.82 V, 5.11 mΩ-cm 2 , and 606 V, respectively. The breakdown voltage was further increased up to 1.1 kV by inserting 2 floating metal rings at a 50-µm-long drift length. The oxidation process is suitable for high-voltage GaN devices with Ni-based Schottky contacts.