A noncontact thermal microprobe for local thermal conductivity measurement

Area of Science:

• Materials Science
• Nanotechnology
• Thermal Physics

Background:

• Accurate measurement of thermal conductivity (κ) is crucial for understanding heat transport in nanomaterials.
• Conventional contact-based thermal probing methods are sensitive to surface topography and chemistry, limiting their applicability.
• Developing noncontact techniques is essential for reliable thermal characterization of diverse nanostructures.

Purpose of the Study:

• To demonstrate a noncontact thermal microprobe technique for measuring thermal conductivity (κ) with high spatial resolution.
• To overcome the limitations of contact-based methods by minimizing surface interactions.
• To enable the thermal characterization of a wider range of nanomaterials.

Main Methods:

• Utilizing a joule-heated microprobe and a 10-100 nm air gap to exploit quasiballistic air conduction.
• Extracting thermal conductivity (κ) from measured effective thermal resistance and calibrated tip-sample thermal contact parameters.
• Employing a heat transfer model and reference samples for accurate calibration in the quasiballistic regime.

Main Results:

• Achieved a lateral spatial resolution of approximately 3 μm for thermal conductivity (κ) measurements.
• Obtained κ values within 5%-10% agreement with standard steady-state methods and theoretical predictions.
• Demonstrated successful characterization of nanostructured bulk and thin film assemblies of pnictogen chalcogenides.

Conclusions:

• The noncontact thermal microprobe technique provides accurate thermal conductivity (κ) measurements for nanomaterials.
• This method mitigates issues related to surface chemistry and topography inherent in contact methods.
• The technique broadens the scope of thermal characterization for various nanomaterials.