期刊
JOURNAL OF APPLIED PHYSICS
卷 117, 期 11, 页码 -出版社
AMER INST PHYSICS
DOI: 10.1063/1.4913826
关键词
-
资金
- R. A. Welch Foundation [D-1126]
It is generally accepted that heat-carrying phonons in materials scatter off each other (normal or Umklapp scattering) as well as off defects. This assumes static defects, implies quasi-instantaneous interactions and at least some momentum transfer. However, when defect dynamics are explicitly included, the nature of phonon-defect interactions becomes more subtle. Ab initio microcanonical molecular-dynamics simulations show that (1) spatially localized vibrational modes (SLMs), associated with all types of defects in semiconductors, can trap thermal phonons; (2) the vibrational lifetimes of excitations in SLMs are one to two orders of magnitude longer (dozens to hundreds of periods of oscillation) than those of bulk phonons of similar frequency; (3) it is phonon trapping by defects (in SLMs) rather than bulk phonon scattering, which reduces the flow of heat; and (4) the decay of trapped phonons and therefore heat flow can be predicted and controlled-at least to some extent-by the use of carefully selected interfaces and delta layers. (C) 2015 AIP Publishing LLC.
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