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A Sn-doped (100) β-Ga2O3 epitaxial layer was grown via metal-organic vapor phase epitaxy (MOVPE) onto a singlecrystal, Mg-doped semi-insulating (100) β-Ga2O3 substrate. Ga2O3-based Metal-Oxide-Semiconductor Field effect Transistors (MOSFETs) with a 2 µm gate length (LG), 3.4 µm source-drain spacing (LSD) and 0.6 µm gate-drain spacing (LGD) were fabricated and characterized. Devices were observed to hold a gate-to-drain voltage of 230 V in the off-state. The gate-to-drain electric field corresponds to 3.8 MV/cm, which is the highest reported for any transistor and surpassing bulk GaN and SiC theoretical limits. Further performance projections are made based on layout, process, and material optimizations to be considered in future iterations.

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Sn-doped gallium oxide (Ga2O3) wrap-gate fin-array field-effect transistors (finFETs) were formed by top-down BCl3 plasma etching on a native semi-insulating Mg-doped (100) β-Ga2O3 substrate. The fin channels have a triangular cross-section and are approximately 300 nm wide and 200 nm tall. FinFETs, with 20 nm Al2O3 gate dielectric and ∼2 μm wrap-gate, demonstrate normally-off operation with a threshold voltage between 0 and +1 V during high-voltage operation. The ION/IOFF ratio is greater than 105 and is mainly limited by high on-resistance that can be significantly improved. At VG = 0, a finFET with 21 μm gate-drain spacing achieved a three-terminal breakdown voltage exceeding 600 V without a field-plate.