Interpretation of thermoreflectance measurements with a two-temperature model including non-surface heat deposition

Journal Article · Mon Dec 21 00:00:00 EST 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4937995· OSTI ID:22493070

Regner, K. T.; Wei, L. C. ^[1]

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1. Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

We develop a solution to the two-temperature diffusion equation in axisymmetric cylindrical coordinates to model heat transport in thermoreflectance experiments. Our solution builds upon prior solutions that account for two-channel diffusion in each layer of an N-layered geometry, but adds the ability to deposit heat at any location within each layer. We use this solution to account for non-surface heating in the transducer layer of thermoreflectance experiments that challenge the timescales of electron-phonon coupling. A sensitivity analysis is performed to identify important parameters in the solution and to establish a guideline for when to use the two-temperature model to interpret thermoreflectance data. We then fit broadband frequency domain thermoreflectance (BB-FDTR) measurements of SiO{sub 2} and platinum at a temperature of 300 K with our two-temperature solution to parameterize the gold/chromium transducer layer. We then refit BB-FDTR measurements of silicon and find that accounting for non-equilibrium between electrons and phonons in the gold layer does lessen the previously observed heating frequency dependence reported in Regner et al. [Nat. Commun. 4, 1640 (2013)] but does not completely eliminate it. We perform BB-FDTR experiments on silicon with an aluminum transducer and find limited heating frequency dependence, in agreement with time domain thermoreflectance results. We hypothesize that the discrepancy between thermoreflectance measurements with different transducers results in part from spectrally dependent phonon transmission at the transducer/silicon interface.

• OSTI ID: 22493070
• Journal Information: Journal of Applied Physics, Vol. 118, Issue 23; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALUMINIUM
AXIAL SYMMETRY
CHROMIUM
CYLINDRICAL CONFIGURATION
DIFFUSION EQUATIONS
ELECTRON-PHONON COUPLING
FREQUENCY DEPENDENCE
GOLD
HEAT TRANSFER
HEATING
MATHEMATICAL SOLUTIONS
PLATINUM
SENSITIVITY ANALYSIS
SILICON
SILICON OXIDES
TRANSDUCERS