Tailoring thermal conductivity by engineering compositional gradients in Si1−xGe x superlattices

Pablo Ferrando-Villalba, Aitor F. Lopeandía*, Francesc Xavier Alvarez, Biplab Paul, Carla de Tomás, Maria Isabel Alonso, Miquel Garriga, Alejandro R. Goñi, Jose Santiso, Gemma Garcia, Javier Rodriguez-Viejo

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

29 Citations (Scopus)


The transport properties of artificially engineered superlattices (SLs) can be tailored by incorporating a high density of interfaces in them. Specifically, SiGe SLs with low thermal conductivity values have great potential for thermoelectric generation and nano-cooling of Si-based devices. Here, we present a novel approach for customizing thermal transport across nanostructures by fabricating Si/Si1−xGex SLs with well-defined compositional gradients across the SiGe layer from x = 0 to 0.60. We demonstrate that the spatial inhomogeneity of the structure has a remarkable effect on the heat-flow propagation, reducing the thermal conductivity to ∼2.2 W·m−1·K−1, which is significantly less than the values achieved previously with non-optimized long-period SLs. This approach offers further possibilities for future applications in thermoelectricity. [Figure not available: see fulltext.]

Original languageEnglish
Pages (from-to)2833-2841
Number of pages9
JournalNano Research
Issue number9
Publication statusPublished - 15 Sept 2015


  • composition gradients
  • heat transport
  • SiGe superlattices
  • thermal conductivity


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