Depletion-mode Ga₂O₃ metal-oxide-semiconductor field-effect transistors on β-Ga₂O₃ (010) substrates and temperature dependence of their device characteristics

Single-crystal gallium oxide (Ga₂O₃) metal-oxide-semiconductor field-effect transistors were fabricated on a semi-insulating β-Ga₂O₃ (010) substrate. A Sn-doped n-Ga₂O₃ channel layer was grown by molecular-beam epitaxy. Si-ion implantation doping was performed to source and drain electrode regions for obtaining low-resistance ohmic contacts. An Al₂O₃ gate dielectric film formed by atomic layer deposition passivated the device surface and significantly reduced gate leakage. The device with a gate length of 2 μm showed effective gate modulation of the drain current with an extremely low off-state drain leakage of less than a few pA/mm, leading to a high drain current on/off ratio of over ten orders of magnitude. A three-terminal off-state breakdown voltage of 370 V was achieved. Stable transistor operation was sustained at temperatures up to 250 $°C$⁠.