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Precise control of thermal conductivity at the nanoscale through individual phonon-scattering barriers

2010; Nature Portfolio; Volume: 9; Issue: 6 Linguagem: Inglês

10.1038/nmat2752

1476-4660

Gilles Pernot, M. Stoffel, Ivana Savić, Fabio Pezzoli, P. Chen, G. Savelli, A. Jacquot, J. Schumann, U. Denker, Ingolf Mönch, Christoph Deneke, Oliver G. Schmidt, J.-M. Rampnoux, S. Wang, M. Plissonnier, Armando Rastelli, S. Dilhaire, Natalio Mingo,

Advanced Thermoelectric Materials and Devices

The ability to precisely control the thermal conductivity (kappa) of a material is fundamental in the development of on-chip heat management or energy conversion applications. Nanostructuring permits a marked reduction of kappa of single-crystalline materials, as recently demonstrated for silicon nanowires. However, silicon-based nanostructured materials with extremely low kappa are not limited to nanowires. By engineering a set of individual phonon-scattering nanodot barriers we have accurately tailored the thermal conductivity of a single-crystalline SiGe material in spatially defined regions as short as approximately 15 nm. Single-barrier thermal resistances between 2 and 4 x 10(-9) m(2) K W(-1) were attained, resulting in a room-temperature kappa down to about 0.9 W m(-1) K(-1), in multilayered structures with as little as five barriers. Such low thermal conductivity is compatible with a totally diffuse mismatch model for the barriers, and it is well below the amorphous limit. The results are in agreement with atomistic Green's function simulations.