Low Thermal Boundary Resistance Interfaces for GaN-on-Diamond Devices

Area of Science:

• Materials Science
• Thermal Engineering
• Semiconductor Physics

Background:

• Gallium Nitride (GaN)-on-diamond technology is vital for high-power density electronics.
• Dielectric interlayers between GaN and diamond significantly impact thermal resistance.
• Optimizing these interfaces is key to improving device performance.

Purpose of the Study:

• To investigate the influence of different interfacial layers (AlN, SiN, none) on the thermal resistance of GaN/diamond structures.
• To quantify the thermal boundary resistance (TBR) for each interface configuration.
• To understand the microstructural mechanisms governing heat transfer across these interfaces.

Main Methods:

• Utilized time-domain thermoreflectance (TDTR) for precise TBR measurements.
• Employed electron energy loss spectroscopy (EELS) for interfacial characterization.
• Fabricated GaN/diamond structures with varying 5 nm interlayers: AlN, SiN, and a control without interlayer.

Main Results:

• A SiN interlayer exhibited the lowest thermal boundary resistance (<10 m²K/GW).
• Formation of an Si-C-N layer at the SiN interface was identified as the reason for reduced TBR.
• AlN and no-interlayer samples showed significantly higher TBR (>20 m²K/GW) due to interface roughening and phonon scattering.

Conclusions:

• SiN interlayers are highly effective in reducing thermal resistance in GaN-on-diamond devices.
• Interface engineering, specifically the formation of Si-C-N, is critical for efficient heat management.
• Protecting the GaN surface during growth is essential to prevent interfacial degradation and maintain low thermal resistance.