2D Amorphous GaO_X Gate Dielectric for β-Ga₂O₃ Field-Effect Transistors

Area of Science:

• Materials Science
• Semiconductor Physics
• Nanotechnology

Background:

• Fabricating metal-insulator-semiconductor field-effect transistors (MISFETs) requires suitable gate dielectrics, which is challenging for compound semiconductors due to the lack of high-quality native oxides.
• Beta-phase gallium oxide (β-Ga2O3) is a promising next-generation power semiconductor material due to its ultrawide energy bandgap (4.5-4.9 eV).

Purpose of the Study:

• To develop and characterize a novel 2D amorphous gallium oxide (GaOx) gate dielectric for β-Ga2O3 MISFETs.
• To investigate the performance and stability of MISFETs fabricated with the new GaOx dielectric and β-Ga2O3 channel.

Main Methods:

• Fabrication of 2D amorphous gallium oxide (GaOx) with precisely controlled atomic-scale thickness using the liquid-gallium squeezing technique.
• Integration of the GaOx dielectric with a β-Ga2O3 conducting nanolayer to form MISFET devices.
• Characterization of the MISFET performance, including stability, gate-voltage swing, current on/off ratio, carrier mobility, and breakdown voltage.

Main Results:

• A stable β-Ga2O3 MISFET operating up to 250 °C was successfully fabricated using the 2D amorphous GaOx dielectric.
• The GaOx dielectric formed a high-quality, uniform, and scalable interface with the β-Ga2O3 channel.
• The fabricated MISFET demonstrated a wide gate-voltage swing (+5 V), high current on/off ratio, moderate mobility, and a breakdown voltage of ~138 V.

Conclusions:

• The liquid-gallium squeezing technique enables the room-temperature fabrication of 2D amorphous GaOx gate dielectrics.
• The developed GaOx/β-Ga2O3 MIS structure is suitable for facile fabrication of high-performance MISFET devices.
• This work presents a viable solution for gate dielectric challenges in compound semiconductor-based power electronics.