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

TLDR

The authors fabricated single‑crystal Ga₂O₃ MOSFETs on β‑Ga₂O₃ (010) substrates by MBE‑grown Sn‑doped n‑Ga₂O₃ channels, Si‑ion‑implanted source/drain contacts, and ALD‑deposited Al₂O₃ gate dielectrics that suppress leakage. A 2 µm‑gate device achieved gate‑controlled drain currents with off‑state leakage below a few pA/mm, an on/off ratio exceeding 10¹⁰, a 3‑terminal breakdown voltage of 370 V, and remained stable up to 250 °C.

Abstract

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.