Calibration of thermocouple-based scanning thermal microscope in active mode (2ω method).

Area of Science:

• Materials Science
• Nanotechnology
• Thermal Analysis

Background:

• Accurate measurement of solid material thermal conductivity is crucial for various applications.
• Scanning thermal microscopy (STM) offers high-resolution thermal property mapping.
• Calibration of STM probes is essential for reliable quantitative measurements.

Purpose of the Study:

• To present a calibration procedure for a scanning thermal microscopy probe.
• To investigate the probe's thermal interaction with solid samples in different environments.
• To determine the measurement range and uncertainty of the technique.

Main Methods:

• Utilized a microthermocouple wire probe on a quartz tuning fork in active and modulated modes.
• Performed measurements on reference samples in vacuum and ambient air.
• Employed analytical modeling based on heat equation resolution and thermal conductance networks.

Main Results:

• Observed distinct differences in probe-sample thermal interaction between vacuum and ambient air.
• Found that the effective thermal contact radius is sample-dependent in air but constant in vacuum.
• Established a measurement range, with maximum measurable thermal conductivities of ~23 W m⁻¹ K⁻¹ (vacuum) and ~37 W m⁻¹ K⁻¹ (air).

Conclusions:

• The developed calibration procedure enables accurate thermal conductivity measurements of solids.
• Environmental conditions significantly influence the probe-sample thermal interaction and measurement accuracy.
• The technique provides lowest uncertainties for materials with thermal conductivity below 5 W m⁻¹ K⁻¹.