Pulse accumulation, radial heat conduction, and anisotropic thermal conductivity in pump-probe transient thermoreflectance

Aaron J Schmidt; Xiaoyuan Chen; Gang Chen

doi:10.1063/1.3006335

Pulse accumulation, radial heat conduction, and anisotropic thermal conductivity in pump-probe transient thermoreflectance

Rev Sci Instrum. 2008 Nov;79(11):114902. doi: 10.1063/1.3006335.

Authors

Aaron J Schmidt¹, Xiaoyuan Chen, Gang Chen

Affiliation

¹ Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA. aarons@mit.edu

PMID: 19045906
DOI: 10.1063/1.3006335

Abstract

The relationship between pulse accumulation and radial heat conduction in pump-probe transient thermoreflectance (TTR) is explored. The results illustrate how pulse accumulation allows TTR to probe two thermal length scales simultaneously. In addition, the conditions under which radial transport effects are important are described. An analytical solution for anisotropic heat flow in layered structures is given, and a method for measuring both cross-plane and in-plane thermal conductivities of thermally anisotropic thin films is described. As verification, the technique is used to extract the cross-plane and in-plane thermal conductivities of highly ordered pyrolytic graphite. Results are found to be in good agreement with literature values.