Role of Disorder and Anharmonicity in the Thermal Conductivity of Silicon-Germanium Alloys: A First-Principles Study
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Garg-2011-Role of Disorder and.pdf
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Author(s)
Garg, Jivtesh
Bonini, Nicola
Marzari, Nicola
Kozinsky, Boris, 1978-
Date Issued
January 2011
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Garg, Jivtesh et al. "Role of Disorder and Anharmonicity in the Thermal Conductivity of Silicon-Germanium Alloys: A First-Principles Study." Phys. Rev. Lett. 106, 045901 (2011).© 2011 American Physical Society.
Version
Final published version
Abstract
The thermal conductivity of disordered silicon-germanium alloys is computed from density-functional perturbation theory and with relaxation times that include both harmonic and anharmonic scattering terms. We show that this approach yields an excellent agreement at all compositions with experimental results and provides clear design rules for the engineering of nanostructured thermoelectrics. For SixGe1-x, more than 50% of the heat is carried at room temperature by phonons of mean free path greater than 1 μm, and an addition of as little as 12% Ge is sufficient to reduce the thermal conductivity to the minimum value achievable through alloying. Intriguingly, mass disorder is found to increase the anharmonic scattering of phonons through a modification of their vibration eigenmodes, resulting in an increase of 15% in thermal resistivity.
MIT Department
Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies
Massachusetts Institute of Technology. Department of Materials Science and Engineering
Massachusetts Institute of Technology. Department of Mechanical Engineering
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DOI of Published Version
https://doi.org/10.1103/PhysRevLett.106.045901
