Tailoring thermal conductivity by engineering compositional gradients in Si1−x Ge x superlattices
SiGe superlattices, thermal conductivity, composition gradients, heat transport
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.
Tsinghua University Press
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, Tailoring thermal conductivity by engineering compositional gradients in Si1−x Ge x superlattices. NanoRes.2015, 8(9): 2833–2841