Near-ideal vertical β-Ga2O3 Schottky diode reverse leakage current via sputtered ultra-high-κ BaTiO3 dielectric field-management

We report the use of ultra-high-κ BaTiO3 films deposited via RF sputtering for field management in vertical β-Ga2O3 Schottky barrier diodes. The reverse leakage current for field-plated devices with varying oxide thickness is compared to a theoretical 1-D reverse leakage current that includes thermionic emission with image-force lowering (IFL) and tunneling current. We find near-ideal agreement in leakage current with a thin BaTiO3 field oxide layer and slight deviation from the modeled current as the BaTiO3 gets thicker due to enhanced field-crowding at the anode edge. The effect of increasing BaTiO3 layer thickness on increased field at the anode edge is validated using a Silvaco Victory Device TCAD model. In addition, we show that for a device operating temperature of 150 °C, the measured reverse characteristics deviate substantially from the theoretical leakage, presumably due to thermally excited electron emission over the 80 meV band offset between BaTiO3 and β-Ga2O3. Finally, we demonstrate an Al2O3 interlayer with the BaTiO3 to decrease thermally induced leakage. The mitigation of thermal electron emission improves the agreement between measured and theoretical leakage at 150 °C. These results show the efficacy of a high-κ dielectric field-management layer in vertical β-Ga2O3 devices, which will be critical due to the absence of shallow p-type dopants in β-Ga2O3. This provides a path forward to realizing the potential of β-Ga2O3 power devices.