On the importance of optical phonons to thermal conductivity in nanostructures

Author(s)
Tian, Zhiting; Esfarjani, Keivan; Shiomi, Junichiro; Henry, Asegun; Chen, Gang
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Abstract
The contribution of optical phonons to thermal conductivity has typically been ignored. However, when the system size decreases to the nanoscale regime, optical phonons are no longer negligible. In this study, the contributions of different phonon polarizations to the thermal conductivity of silicon are discussed based on the phonon lifetimes extracted from a first principles approach. The results indicate that around room temperature, optical phonons can contribute over 20% to the thermal conductivity of nanostructures as compared to 5% in bulk materials. In addition, the temperature and size dependence of the contributions from acoustic and optical phonons are fully explored.
Date issued
2011-08
URI
http://hdl.handle.net/1721.1/78257
Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
Journal
Applied Physics Letters
Publisher
American Institute of Physics (AIP)
Citation
Tian, Zhiting et al. “On the Importance of Optical Phonons to Thermal Conductivity in Nanostructures.” Applied Physics Letters 99.5 (2011): 053122. © 2011 American Institute of Physics
Version: Final published version
ISSN
0003-6951
1077-3118
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