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Direct measurement of room-temperature nondiffusive thermal transport over micron distances in a silicon membrane
Johnson, Jeremy A.; Maznev, A. A.; Cuffe, John; Eliason, Jeffrey K.; Minnich, Austin J.; Kehoe, Timothy; Sotomayor Torres, Clivia M.; Chen, Gang; Nelson, Keith A.
The "textbook" phonon mean free path of heat carrying phonons in silicon at room temperature is similar to 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 similar to 1-10 mu m. 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. DOI: 10.1103/PhysRevLett.110.025901
Keyword(s): Thin films; Conduction; Scattering; Gratings; Dynamics; Carrier
Publication Date:
2013
Type: Journal article
Peer-Reviewed: Yes
Language(s): English
Institution: University College Cork
Citation(s): Johnson, J. A., Maznev, A. A., Cuffe, J., Eliason, J. K., Minnich, A. J., Kehoe, T., Torres, C. M. S., Chen, G. and Nelson, K. A. (2013) 'Direct measurement of room-temperature nondiffusive thermal transport over micron distances in a silicon membrane', Physical Review Letters, 110(2), 025901 (5pp). doi: 10.1103/PhysRevLett.110.025901
Publisher(s): American Physical Society
File Format(s): application/pdf
Related Link(s): https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.110.025901
First Indexed: 2017-09-06 06:40:22 Last Updated: 2017-09-06 06:40:22