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

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.

Thermal boundary conductance of transition metals on diamond

“…Since the recorded signal is low, passive frequency ltering, followed by preampli cation and lock-in detection, at the frequency of the pump modulation is used to improve the signal to noise ratio. The obtained cooling curve is not only affected by the thermal properties of the surface material as well as the layers beneath it, but also by heat-accumulation effects due to the high repetition rate of the laser (Cahill 2004;Costescu et al, 2003;Schmidt et al, 2008). To further improve the reliability of the measurement, both the in-phase (X) and out-of-phase (Y) signals recorded by the lock-in ampli er are used.…”

Temperature-Dependent Mean Free Path Spectra of Thermal Phonons Along the c-Axis of Graphite

“…TDTR is a standard characterization method in the thermal sciences that operates by impulsively heating a sample with a laser pulse and observing the transient thermal decay with a probe beam. The thermal conductivity is obtained by fitting the thermal decay curve to a thermal model [7,30]. In this study, we use a two-tint implementation of this method as described in Ref.…”

Disparate quasiballistic heat conduction regimes from periodic heat sources on a substrate

“…We compute the peak temperature rise of the heaters which corresponds to the measured signal in the TDTR experiment 7,21 and is also of interests for microelectronics and nanowire/nanotube based thermal interface materials.…”