Ozone Surface Pretreatment for Enhanced β-Ga₂O₃/Dielectric Interface Engineering.

Area of Science:

• Materials Science
• Semiconductor Physics
• Surface Chemistry

Background:

• Gallium oxide (Ga2O3) is a promising ultra-wide bandgap semiconductor for power electronics.
• Achieving high-quality gate dielectric interfaces is crucial for optimizing Ga2O3-based devices.
• Existing surface treatments for Ga2O3 often fail to prevent carbon contamination during dielectric deposition.

Purpose of the Study:

• To investigate the effectiveness of various oxidative surface treatments on β-Ga2O3.
• To identify the cause of performance discrepancies despite carbon reduction.
• To develop an improved surface treatment strategy for β-Ga2O3/Al2O3 interfaces.

Main Methods:

• In situ X-ray photoelectron spectroscopy (XPS) for surface analysis.
• Ex situ capacitance-voltage (C-V) measurements for electrical characterization.
• Atomic layer deposition (ALD) for dielectric layer growth.
• Ozone (O3) prepulsing as a novel surface treatment.

Main Results:

• Standard oxidative treatments (O2 plasma, UV-O3, O2 annealing) reduced surface carbon but did not improve electrical performance.
• Carbon readsorption during ALD thermal equilibration was identified as the limiting factor.
• O3 prepulsing immediately before ALD significantly reduced carbon contamination and improved interface quality.
• Marked improvements in flat-band voltage, interface trap density, and frequency dispersion were observed with O3 prepulsing.

Conclusions:

• Ozone prepulsing is a highly effective method for decontaminating β-Ga2O3 surfaces prior to Al2O3 dielectric deposition.
• This technique minimizes the window for carbonaceous species readsorption, leading to superior interface properties.
• O3 prepulsing offers a practical and scalable solution for fabricating high-performance β-Ga2O3 metal-oxide-semiconductor devices.