Properties for Thermally Conductive Interfaces with Wide Band Gap Materials

Area of Science:

• Materials Science
• Solid-State Physics
• Nanotechnology

Background:

• Understanding thermal transport at interfaces is crucial for designing advanced semiconductor devices.
• Wide band gap semiconductors are essential for high-power and high-frequency applications.
• Interfacial thermal conductance is influenced by material properties and structure.

Purpose of the Study:

• To investigate the impact of bulk vibrational properties and interfacial structure on thermal transport.
• To systematically study thermal conductance at interfaces between nitride metals and various semiconductors.
• To identify key material properties governing high thermal conductance at interfaces.

Main Methods:

• Time-Domain Thermoreflectance (TDTR) measurements to determine thermal conductance (G).
• Analysis of bulk vibrational properties of constituent materials.
• Transmission Electron Microscopy (TEM) to characterize interfacial structure.

Main Results:

• Observed thermal conductances for HfN interfaces ranged from 140 to 300 MW m⁻² K⁻¹, and for TiN interfaces from 200 to 800 MW m⁻² K⁻¹.
• TiN formed highly conductive interfaces (G > 400 MW m⁻² K⁻¹) with GaN, AlN, and diamond.
• Surprisingly, interfaces with similar and dissimilar vibrational properties exhibited comparable conductances, indicating vibrational similarity is not essential for high G.
• Interfacial disorder significantly increases thermal resistance, equivalent to ~1 nm of amorphous material in TiN/AlN interfaces.

Conclusions:

• Bulk phonon properties of the softer material and interfacial structure are primary determinants of interfacial thermal conductance.
• Vibrational similarity is not a prerequisite for high thermal conductance at wide band gap semiconductor interfaces.
• Findings provide fundamental insights and benchmarks for designing thermally conductive interfaces in wide band gap systems.