In this study, MOSFETs fabricated on Si-doped, MBE-grown β-Ga₂O₃ are demonstrated. A Si-doped Ga₂O₃ epitaxial layer was grown on a Fe-doped, semi-insulating 1.5 cm × 1 cm Ga₂O₃ substrate using molecular beam epitaxy (MBE). The fabricated devices are circular type MOSFETs with a gate length of 3 μm, a source-drain spacing of 20 μm, and a gate width of 523 μm. The device exhibited a good pinch-off characteristic, a high on-off drain current ratio of approximately 2.7×10⁹, and a high breakdown voltage of 1,080 V, which demonstrates the potential of Ga₂O₃ for power device applications including electric vehicles, railways, and renewable energy.

This report constitutes the first demonstration in Korea of single-crystal lateral gallium oxide (Ga₂O₃) as a metal-oxide-semiconductor field-effect-transistor (MOSFET), with a breakdown voltage in excess of 480 V. A Si-doped channel layer was grown on a Fe-doped semi-insulating β-Ga₂O₃ (010) substrate by molecular beam epitaxy. The single-crystal substrate was grown by the edge-defined film-fed growth method and wafered to a size of 10×15 mm². Although we fabricated several types of power devices using the same process, we only report the characterization of a finger-type MOSFET with a gate length (L_g) of 2 μm and a gate-drain spacing (L_gd) of 5 μm. The MOSFET showed a favorable drain current modulation according to the gate voltage swing. A complete drain current pinch-off feature was also obtained for V_gs<-6 V, and the three-terminal off-state breakdown voltage was over 482 V in a L_gd＝5 μm device measured in Fluorinert ambient at V_gs＝-10 V. A low drain leakage current of 4.7 nA at the off-state led to a high on/off drain current ratio of approximately 5.3×10⁵. These device characteristics indicate the promising potential of Ga₂O₃-based electrical devices for next-generation high-power device applications, such as electrical autonomous vehicles, railroads, photovoltaics, renewable energy, and industry.