Direct Measurement of Room-Temperature Nondiffusive Thermal Transport Over Micron Distances in a Silicon Membrane
Author(s)
Johnson, Jeremiah A.; Maznev, Alexei; Eliason, Jeffrey Kristian; Nelson, Keith Adam; Cuffe, John; Minnich, Austin Jerome; Kehoe, Timothy; Torres, Clivia M. Sotomayor; Chen, Gang; ... Show more Show less
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The “textbook” phonon mean free path of heat carrying phonons in silicon at room temperature is ∼40 nm. However, a large contribution to the thermal conductivity comes from low-frequency phonons with much longer mean free paths. We present a simple experiment demonstrating that room-temperature thermal transport in Si significantly deviates from the diffusion model already at micron distances. Absorption of crossed laser pulses in a freestanding silicon membrane sets up a sinusoidal temperature profile that is monitored via diffraction of a probe laser beam. By changing the period of the thermal grating we vary the heat transport distance within the range ∼1–10 μm. At small distances, we observe a reduction in the effective thermal conductivity indicating a transition from the diffusive to the ballistic transport regime for the low-frequency part of the phonon spectrum.
Date issued
2013-01Department
Massachusetts Institute of Technology. Department of Chemistry; Massachusetts Institute of Technology. Department of Mechanical EngineeringJournal
Physical Review Letters
Publisher
American Physical Society
Citation
Johnson, Jeremy A. et al. “Direct Measurement of Room-Temperature Nondiffusive Thermal Transport Over Micron Distances in a Silicon Membrane.” Physical Review Letters 110.2 (2013). © 2013 American Physical Society
Version: Final published version
ISSN
0031-9007
1079-7114