Phonon relaxation time reconstruction from transient thermal grating experiments and comparison with density functional theory predictions

Journal Article · Wed Jan 16 00:00:00 EST 2019 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.5062846· OSTI ID:1566655

Forghani, Mojtaba  ^[1]; Hadjiconstantinou, Nicolas G. ^[1]

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1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Mechanical Engineering

Phonon relaxation time and free path distributions are reconstructed from experimental measurements on a two-dimensional transient thermal grating and compared with density functional theory (DFT) results for silicon. The reconstruction is performed using the inverse problem formulation of Forghani et al. [Phys. Rev. B 94, 155439 (2016)]. The discrepancies observed between reconstructed and DFT results are analyzed in terms of the ability of each set of data to reproduce the experimental temperature relaxation profiles; the reconstructed data are found to predict temperature profiles in closer agreement with the experimental data than the DFT results, possibly due to discrepancies between the actual material and the idealized model studied in the DFT calculations. The reconstructed phonon properties accurately predict temperature relaxation profiles at grating length scales smaller than those spanned by the experimental data. Finally, this is a very important feature since in a variety of experimental setups, including the one providing the data in the present study, measurements are not available at all scales spanned by the material free paths.

• Research Organization: Energy Frontier Research Centers (EFRC) (United States). Solid-State Solar-Thermal Energy Conversion Center (S3TEC); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0001299; FG02-09ER46577
• OSTI ID: 1566655
• Journal Information: Applied Physics Letters, Vol. 114, Issue 2; ISSN 0003-6951
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

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