Thermal conductivities of Si1-xGex nanowires with different germanium concentrations and diameters

The thermal conductivities of Si1-xGex nanowires (NWs) synthesized with Ge concentrations of 0.0%, 0.4%, 4%, and 9% and different diameters were measured from 40 to 420 K. The thermal conductivity of Si1-xGex NWs decreases as the Ge concentration increases due to alloy scattering. As the diameter of the Si1-xGex NWs decreases, the thermal conductivity decreases due to phonon boundary scattering. However, the thermal conductivity dependency on the diameter of the NWs is not significant. This indicates that alloy scattering should be the dominant scattering mechanism in Si1-xGex NWs. This study should provide a basis for designing efficient thermoelectric devices out of Si1-xGex NWs and Si1-xGex nanocomposites. (C) 2010 American Institute of Physics. [doi:10.1063/1.3443707]