Gallium oxide (Ga2O3) metal-semiconductor field-effect transistors on single-crystal β-Ga2O3 (010) substrates

We report a demonstration of single-crystal gallium oxide (Ga₂O₃) metal-semiconductor field-effect transistors (MESFETs). A Sn-doped Ga₂O₃ layer was grown on a semi-insulating β-Ga₂O₃ (010) substrate by molecular-beam epitaxy. We fabricated a circular MESFET with a gate length of 4 μm and a source-drain spacing of 20 μm. The device showed an ideal transistor action represented by the drain current modulation due to the gate voltage (V_GS) swing. A complete drain current pinch-off characteristic was also obtained for V_GS < -20 V, and the three-terminal off-state breakdown voltage was over 250 V. A low drain leakage current of 3 μA at the off-state led to a high on/off drain current ratio of about 10 000. These device characteristics obtained at the early stage indicate the great potential of Ga₂O₃-based electrical devices for future power device applications.