Thermal conductivity measurements of high and low thermal conductivity films using a scanning hot probe method in the 3ω mode and novel calibration strategies

Abstract

This work discusses measurement of thermal conductivity (k) of films using a scanning hot probe method in the 3ω mode and investigates the calibration of thermal contact parameters, specifically the thermal contact resistance (R(th)C) and thermal exchange radius (b) using reference samples with different thermal conductivities. R(th)C and b were found to have constant values (with b = 2.8 ± 0.3 μm and R(th)C = 44,927 ± 7820 K W(-1)) for samples with thermal conductivity values ranging from 0.36 W K(-1) m(-1) to 1.1 W K(-1) m(-1). An independent strategy for the calibration of contact parameters was developed and validated for samples in this range of thermal conductivity, using a reference sample with a previously measured Seebeck coefficient and thermal conductivity. The results were found to agree with the calibration performed using multiple samples of known thermal conductivity between 0.36 and 1.1 W K(-1) m(-1). However, for samples in the range between 16.2 W K(-1) m(-1) and 53.7 W K(-1) m(-1), calibration experiments showed the contact parameters to have considerably different values: R(th)C = 40,191 ± 1532 K W(-1) and b = 428 ± 24 nm. Finally, this work demonstrates that using these calibration procedures, measurements of both highly conductive and thermally insulating films on substrates can be performed, as the measured values obtained were within 1-20% (for low k) and 5-31% (for high k) of independent measurements and/or literature reports. Thermal conductivity results are presented for a SiGe film on a glass substrate, Te film on a glass substrate, polymer films (doped with Fe nano-particles and undoped) on a glass substrate, and Au film on a Si substrate.

A Review on Principles and Applications of Scanning Thermal Microscopy (SThM)

“…Then, b can be determined from the thermal signal profile occurring at the edge of the step between these two materials. In all, the assumption made by the above methods7a,38f,52b,60,62,71,121,134b,136,151 is a constant . However, proved later to vary with the sample surface (the sample mechanical properties and roughness)65,112b,152 and thermal conductivity 65,111a,153.…”

“…Zhang et al7a developed intersection methods to obtain b by performing measurements of two bulk calibration samples under the assumption of invariant and b for low thermal conductivity samples. Later on, Wilson et al extended this method to various samples in the thermal conductivity range from 0.3–1.1 W m −1 K −1 . Other methods are also used to obtain thermal exchange parameters.…”

“…Considering different type of probes calibration, the above mentioned methodology7,38f,62,71 can be applied to both Wollaston probe and resistive Pd probe 38f,71. However, the highly Si‐doped probe has limited performance for these calibration methods due to nanoscale size effects.…”

Enhancement of thermoelectric efficiency of doped PCDTBT polymer films

“…The 3u-SThM has been used to determine the thermal conductivity of organic and inorganic nanostructures, such as lms 29,30 or nanowires. 28,31 This technique uses a thermoresistive probe that is heated by Joule effect when passing an electrical current through it.…”

Advances in Scanning Thermal Microscopy Measurements for Thin Films

“…Another method proposed in 2008 to perform measurements in ambient condition, was proposed using a double scan technique [28]. Most of these contributions can be separated in applications to 1D structures, such as nanowires [29,30] or carbon nanotubes [31,32], 3D materials [33], thin films [34] (which are the objective of the present chapter), and in the last years, the SThM technique has also been successfully applied to the study of the emerging field of 2D materials [35].…”