Accelerated Aging Stability of β-Ga₂O₃-Titanium/Gold Ohmic Interfaces

Area of Science:

• Materials Science
• Semiconductor Physics
• Electrical Engineering

Background:

• Stable ohmic contacts are essential for efficient high-voltage electronic devices.
• Ultrawide bandgap semiconductors like β-Ga₂O₃ require robust contact interfaces.
• Understanding contact stability under thermal stress is crucial for device reliability.

Purpose of the Study:

• To investigate the thermal aging stability of Ti/Au ohmic contacts on β-Ga₂O₃.
• To correlate interface properties with electrical performance under accelerated aging conditions.
• To establish methods for assessing and optimizing oxide-semiconductor interface stability.

Main Methods:

• Fabrication of Ti/Au ohmic contacts on Si-ion implanted and RIE-treated β-Ga₂O₃.
• Thermally accelerated aging of contacts at 300 °C for 108 hours.
• Electrical characterization (specific contact resistance) and advanced microscopy (SEM/TEM) for structural and elemental analysis.

Main Results:

• Achieved low specific contact resistance (∼10^-5 Ω cm²) on heavily doped, RIE-treated β-Ga₂O₃.
• Demonstrated exceptional thermal stability; low resistance was maintained after aging.
• Identified an interfacial layer and facet-like features contributing to stability and barrier inhomogeneity.

Conclusions:

• Ti/Au contacts on Si-doped, RIE-treated β-Ga₂O₃ offer stable, low-resistance performance.
• The observed interface structure and properties are key to the contact's thermal stability.
• The employed methodologies can guide the development of stable contacts for various oxide semiconductors.