Interface-Driven Electrothermal Degradation in GaN-on-Diamond High Electron Mobility Transistors.

Area of Science:

• Materials Science
• Electrical Engineering
• Semiconductor Physics

Background:

• Diamond's high thermal conductivity makes it ideal for GaN HEMTs.
• Thermal Boundary Resistance (TBR) at the GaN-diamond interface limits heat dissipation.
• Self-heating and performance degradation are critical issues in GaN-on-diamond HEMTs.

Purpose of the Study:

• Investigate the impact of thermal boundary layer (TBL) thickness and thermal conductivity on GaN-on-diamond HEMTs.
• Analyze the electrothermal behavior under varying interface conditions.
• Determine the relative importance of interface quality versus substrate thermal conductivity.

Main Methods:

• Technology Computer-Aided Design (TCAD) simulations were used.
• Systematic investigation of TBL thickness (5-20 nm) and thermal conductivity (0.1-1.0 W/(m·K)).
• Co-analysis of substrate thermal conductivity and interfacial quality.

Main Results:

• Increased TBL thickness or decreased TBL thermal conductivity elevates hotspot temperatures and degrades electron mobility.
• Device performance deteriorates significantly with poorer interfacial thermal properties.
• Interface TBR has a greater impact on device behavior than substrate conductivity.

Conclusions:

• Interface engineering is critical for thermal management in GaN-on-diamond HEMTs.
• Optimized interfaces can compensate for lower substrate thermal conductivity.
• Findings provide a foundation for future research on phonon transport and defect-controlled thermal interfaces.