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Title: Radial quasiballistic transport in time-domain thermoreflectance studied using Monte Carlo simulations

Recently, a pump beam size dependence of thermal conductivity was observed in Si at cryogenic temperatures using time-domain thermal reflectance (TDTR). These observations were attributed to quasiballistic phonon transport, but the interpretation of the measurements has been semi-empirical. Here, we present a numerical study of the heat conduction that occurs in the full 3D geometry of a TDTR experiment, including an interface, using the Boltzmann transport equation. We identify the radial suppression function that describes the suppression in heat flux, compared to Fourier's law, that occurs due to quasiballistic transport and demonstrate good agreement with experimental data. We also discuss unresolved discrepancies that are important topics for future study.
Authors:
; ;  [1]
  1. Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125 (United States)
Publication Date:
OSTI Identifier:
22261580
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 14; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BOLTZMANN EQUATION; COMPUTERIZED SIMULATION; EXPERIMENTAL DATA; HEAT FLUX; MONTE CARLO METHOD; NUMERICAL ANALYSIS; OPTICAL PUMPING; PHONONS; THERMAL CONDUCTIVITY