Direct Measurement of Room-Temperature Nondiffusive Thermal Transport Over Micron Distances in a Silicon Membrane
Journal Article
·
· Physical Review Letters
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Chemistry
- Catalan Inst. of Nanotechnology, Barcelona (Spain); Univ. College Cork (Ireland). Dept. of Physics. Tyndall National Inst.
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Mechanical Engineering
- Catalan Inst. of Nanotechnology, Barcelona (Spain)
- Catalan Inst. of Nanotechnology, Barcelona (Spain); Catalan Inst. for Research and Advanced Studies (ICREA), Barcelona (Spain); Autonomous Univ. of Barcelona (Spain). Dept. of Physics
The “textbook” phonon mean free path of heat carrying phonons in silicon at room temperature is $${\sim}40\text{ }\text{ }\mathrm{nm}$$. However, a large contribution to the thermal conductivity comes from low-frequency phonons with much longer mean free paths. We present here 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 $${\sim}1-10\text{ }\text{ }{\mu}\mathrm{m}$$. 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.
- 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; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- Grant/Contract Number:
- SC0001299
- OSTI ID:
- 1081191
- Alternate ID(s):
- OSTI ID: 1101856
- Journal Information:
- Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 2 Vol. 110; ISSN 0031-9007
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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