Journal
NANO LETTERS
Volume 14, Issue 5, Pages 2448-2455Publisher
AMER CHEMICAL SOC
DOI: 10.1021/nl500127c
Keywords
Phonon transport; amorphous limit; diffusive mismatch model; Debye temperature; superlattice
Categories
Funding
- International Innovation Initiative
- CSRO program of Calit2 at UC San Diego
- Thermal Transport Program of the National Science Foundation [CBET-1336428]
- Office of Naval Research (ONR) Young Investigator Award [N00014-13-1-0535]
- ONR MURI program [N00014-13-1-0678]
- Directorate For Engineering
- Div Of Chem, Bioeng, Env, & Transp Sys [1336428] Funding Source: National Science Foundation
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Thermal transport in multilayers (MLs) has attracted significant interest and shows promising applications. Unlike their single-component counterparts, MLs exhibit a thermal conductivity that can be effectively engineered by both the number density of the layers and the interfacial thermal resistance between layers, with the latter being highly tunable via the contrast of acoustic properties of each layer. In this work, we experimentally demonstrated an ultralow thermal conductivity of 0.33 +/- 0.04 W m(-1) K-1 at room temperature in MLs made of Au and Si with a high interfacial density of similar to 0.2 interface nm(-1). The measured thermal conductivity is significantly lower than the amorphous limit of either Si or Au and is also much lower than previously measured MLs with a similar interfacial density. With a Debye temperature ratio of similar to 3.9 for Au and Si, the Au/Si MLs represent the highest mismatched system in inorganic MLs measured to date. In addition, we explore the prior theoretical prediction that full phonon dispersion could better model the interfacial thermal resistance involving materials with low Debye temperatures. Our results demonstrate that MLs with highly dissimilar Debye temperatures represent a rational approach to achieve ultralow thermal conductivity in inorganic materials and can also serve as a platform for investigating interfacial thermal transport.
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