Experimental Evidence of Superdiffusive Thermal Transport in Si<sub>0.4</sub>Ge<sub>0.6</sub> Thin Films.
basic_science · Level V
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- Record sourced from PubMed, PMID 36054095.
- Also identified by DOI 10.1021/acs.nanolett.2c01050.
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Abstract
Superdiffusive thermal transport represents a unique phenomenon in heat conduction, which is characterized by a size (<i>L</i>) dependence of thermal conductivity (κ) in the form of κ ∝ <i>L</i><sup>β</sup> with a constant β between 0 and 1. Although superdiffusive thermal transport has been theoretically predicted for SiGe alloys, direct experimental evidence is still lacking. Here, we report on a systematic experimental study of the thickness-dependent thermal conductivity of Si<sub>0.4</sub>Ge<sub>0.6</sub> thin films grown by molecular beam epitaxy. The cross-plane thermal conductivity of Si<sub>0.4</sub>Ge<sub>0.6</sub> thin films spanning a thickness range from 20 to 1120 nm was measured in the temperature range 120-320 K via a differential three-omega method. Results show that the thermal conductivity follows a consistent κ ∝ <i>t</i><sup>0.26</sup> power law with the film thickness (<i>t</i>) at different temperatures, providing direct experimental evidence that alloy-scattering dominated thermal transport in SiGe is superdiffusive.