Internal Field Optimization Using a Localized Bottom SiO 2 in Vertical β-Ga 2 O 3 FinFETs

Vertical β-Ga2O3FinFETs are promising candidates for high-voltage power switching because they enable normally-off operation through geometric depletion while leveraging the ultra-wide bandgap for high electric-field blocking. However, premature breakdown can still be triggered by severe electric-field crowding at the trench bottom corners. In this work, we demonstrate a vertical β-Ga2O3FinFET with enhanced reverse blocking enabled by an internal field-optimization (IFO) structure, realized by introducing an 100nm SiO2dielectric liner locally at the fin bottom/corner regions. Owing to the dielectric field management, the device achieves a breakdown voltage of 1440 V, representing a substantial improvement over the control device without IFO. The FinFET exhibits enhancement-mode characteristics with VTH=1.31 V, a subthreshold swing of 98.8 mV/dec, an on/off current ratio of 109, and a strongly suppressed transfer hysteresis of 15 mV. A maximum drain current density of 519.4 A/cm2, with a differential specific on-resistance (Ron,sp) 12 mΩ•cm2. These results highlight dielectric-assisted corner field shaping as a practical route toward simultaneously improving breakdown robustness and maintaining low conduction loss in vertical β-Ga2O3FinFET power transistors.