Session: K9-09: NANOSCALE THERMAL TRANSPORT MODELING AND MACHINE LEARNING I

Paper Number: 131125

131125 - Simulation of Time-Domain Thermo-Reflectance Experiments Using the Anisotropic Fourier Heat Conduction Equation and the Phonon Boltzmann Transport Equation 

Abstract: 

The anisotropic Fourier heat conduction equation (FHCE) and the multidimensional phonon Boltzmann Transport Equation (BTE) were solved numerically in cylindrical coordinates and in time domain to simulate a Time Domain Thermo-Reflectance (TDTR) experimental setup. The out-of-phase response of the probe laser was predicted at various beam offset distances for a pump laser frequency of 80 MHz and compared against experimental measurements for a silicon substrate. The isotropic FHCE was also solved for comparison. Results show that the isotropic FHCE with bulk thermal conductivity significantly underpredicts the out-of-phase temperature, particularly at smaller beam offsets. With an isotropic thermal conductivity of 72% of the bulk value, the computational results match experimental data at smaller beam offsets well, but overpredicts the experimental data at larger beam offsets. A almost-perfect match could be obtained by using an anisotropic thermal conductivity wherein the radial (in-plane) thermal conductivity was set to approximately half its value in the axial (through-plane) direction. The phonon BTE was next solved using the three-phonon scattering time-scales provided by Briodo and co-workers for acoustic phonons, and with the inclusion of optical phonons. The BTE results for the out-of-phase temperature matched experimental observations well at small and intermediate beam offsets, but overpredicted the experimental data at larger beam offsets. Additional studies are conducted and discussed to delineate the effect of lateral (in-plane) conduction in the transducer on the predicted results.

Presenting Author: Sandip Mazumder Ohio State University

Presenting Author Biography: Professor

Authors:

Siddharth Saurav The Ohio State University
Sandip Mazumder Ohio State University