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Nano Research

Article Title

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

Authors

Pablo Ferrando-Villalba, Grup de Nanomaterials i Microsistemes, Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
Aitor F. Lopeandía, Grup de Nanomaterials i Microsistemes, Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
Francesc Xavier Alvarez, Grup de Física Estadística, Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
Biplab Paul, Grup de Nanomaterials i Microsistemes, Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
Carla de Tomás, Grup de Física Estadística, Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
Maria Isabel Alonso, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain
Miquel Garriga, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain
Alejandro R. Goi, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain ICREA, Passeig Lluís Companys 23, 08010 Barcelona, Spain
Jose Santiso, Institut Català de Nanociència i Nanotecnologia, ICN2-CSIC, Campus UAB, 08193 Bellaterra, Spain
Gemma Garcia, Grup de Nanomaterials i Microsistemes, Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
Javier Rodriguez-Viejo, Grup de Nanomaterials i Microsistemes, Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain

Keywords

SiGe superlattices, thermal conductivity, composition gradients, heat transport

Abstract

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.

Graphical Abstract

Publisher

Tsinghua University Press

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