Elsevier

Photoacoustics

Volume 22, June 2021, 100246
Photoacoustics

Research article
Photoacoustic thermal characterization of low thermal diffusivity thin films

https://doi.org/10.1016/j.pacs.2021.100246Get rights and content
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Abstract

The photoacoustic measurement technique is a powerful yet underrepresented method to characterize the thermal transport properties of thin films. For the case of isotropic low thermal diffusivity samples, such as glasses or polymers, we demonstrate a general approach to extract the thermal conductivity with a high degree of significance. We discuss in particular the influence of thermal effusivity, thermal diffusivity, and sample layer thickness on the significance and accuracy of this measurement technique. These fundamental thermal properties guide sample and substrate selection to allow for a feasible thermal transport characterization. Furthermore, our data evaluation allows us to directly extract the thermal conductivity from this transient technique, without separate determination of the volumetric heat capacity, when appropriate boundary conditions are fulfilled. Using silica, poly(methyl methacrylate) (PMMA) thin films, and various substrates (quartz, steel, and silicon), we verify the quantitative correctness of our analytical approach.

Keywords

Thermal conductivity
Thermal wave
Thermal transport metrology
Photoacoustic characterization
Effusivity mismatch
Thermal diffusivity
Thin film characterization
Nanoscale thermal transport

Cited by (0)

Kai Herrmann received his B.Sc. in Nano Science at the University of Hamburg before advancing to the University of Bayreuth for his M.Sc. in Polymer Science. He is now a Ph.D. student at the chair of Physical Chemistry I, working on thermal characterization techniques to gain insights into thermal transport in soft matter.

Nelson W. Pech-May graduated in 2009 as Mechanical Engineer from the Merida Institute of Technology (Mexico). He did his PhD thesis in the field of Photothermal Methods for materials characterization and non-destructive testing and obtained in 2016 a double degree on applied physics from CINVESTAV Unidad Merida (Mexico) and UPV/EHU (Spain). In 2017, he moved to the University of Bayreuth (Germany) for two years postdoc at the chair of Physical Chemistry I. Currently he is hired as postdoc at BAM Berlin (Germany) in division 8.7 Thermographic Methods. His interests are application of active and passive thermography for non-destructive testing and materials characterization.

Markus Retsch received his diploma degree from the University of Bayreuth in the field of Polymer and Colloid Chemistry in 2006. After his PhD thesis at the Max-Planck-Institute for Polymer Research in Mainz, Germany, on complex architectures based on colloidal self-assembly, he moved to the Massachusetts Institute of Technology in 2009. After two years working as a Postdoc at the Department of Materials Science and Engineering, he returned to the University of Bayreuth. Following his Lichtenberg professorship, he became tenured in 2018 and holds the chair for Physical Chemistry I. His interests lie on hierarchically structured, sustainable materials for energy management applications.