Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published June 2021 | Supplemental Material + Submitted + Published
Journal Article Open

Origin of micrometer-scale propagation lengths of heat-carrying acoustic excitations in amorphous silicon

Abstract

The heat-carrying acoustic excitations of amorphous silicon are of interest because their mean free paths may approach micron scales at room temperature. Despite extensive investigation, the origin of the weak acoustic scattering in the heat-carrying frequencies remains a topic of debate. Here, we report measurements of the thermal conductivity mean free path accumulation function in amorphous silicon thin films from 60 to 315 K using transient grating spectroscopy. With additional picosecond acoustics measurements and considering the power-law frequency dependence of scattering mechanisms in glasses, we reconstruct the mean free paths from ∼0.1–3 THz. The mean free paths are independent of temperature and exhibit a Rayleigh scattering trend over most of this frequency range. The observed trend is inconsistent with the predictions of numerical studies based on normal mode analysis but agrees with diverse measurements on other glasses. The micron-scale MFPs in amorphous Si arise from the absence of anharmonic or thermally activated relaxation damping in the sub-THz frequencies, leading to heat-carrying acoustic excitations with room-temperature MFPs comparable to those of other glasses at cryogenic temperatures.

Additional Information

© 2021 American Physical Society. Received 22 July 2020; revised 5 March 2021; accepted 27 April 2021; published 9 June 2021. The authors acknowledge discussions with A. B. Robbins and B. C. Daly. This work was supported by the 2018 GIST-Caltech Research Collaboration.

Attached Files

Published - PhysRevMaterials.5.065602.pdf

Submitted - 2007.15777.pdf

Supplemental Material - SI_PRM.pdf

Files

PhysRevMaterials.5.065602.pdf
Files (10.8 MB)
Name Size Download all
md5:a87ff1c46f20bd2e88b320a40d80714c
1.1 MB Preview Download
md5:1312ab2f5421a7cad8807c5028f1674e
5.7 MB Preview Download
md5:e7247fc2544898d9aee8e845d7e0a798
4.0 MB Preview Download

Additional details

Created:
August 20, 2023
Modified:
October 20, 2023