Reconstructing phonon mean-free-path contributions to thermal conductivity using nanoscale membranes
Knowledge of the mean-free-path distribution of heat-carrying phonons is key to understanding phonon-mediated thermal transport. We demonstrate that thermal conductivity measurements of thin membranes spanning a wide thickness range can be used to characterize how bulk thermal conductivity is distri...
| Main Authors: | , , , , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
American Physical Society
2015
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| Online Access: | http://hdl.handle.net/1721.1/97463 https://orcid.org/0000-0002-3968-8530 https://orcid.org/0000-0001-7804-5418 https://orcid.org/0000-0001-9157-6491 |
| Summary: | Knowledge of the mean-free-path distribution of heat-carrying phonons is key to understanding phonon-mediated thermal transport. We demonstrate that thermal conductivity measurements of thin membranes spanning a wide thickness range can be used to characterize how bulk thermal conductivity is distributed over phonon mean free paths. A noncontact transient thermal grating technique was used to measure the thermal conductivity of suspended Si membranes ranging from 15–1500 nm in thickness. A decrease in the thermal conductivity from 74–13% of the bulk value is observed over this thickness range, which is attributed to diffuse phonon boundary scattering. Due to the well-defined relation between the membrane thickness and phonon mean-free-path suppression, combined with the range and accuracy of the measurements, we can reconstruct the bulk thermal conductivity accumulation vs. phonon mean free path, and compare with theoretical models. |
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