Tunable thermal conductivity of Si1-xGex nanowires

By using molecular dynamics simulation, we demonstrate that the thermal conductivity of silicon-germanium nanowires (Si1-xGex NWs) depends on the composition remarkably. The thermal conductivity reaches the minimum, which is about 18% of that of pure Si NW, when Ge content is 50%. More interesting, with only 5% Ge atoms (Si0.95Ge0.05 NW), SiNW's thermal conductivity is reduced to 50%. The reduction of thermal conductivity mainly comes from the localization of phonon modes due to random scattering. Our results demonstrate that Si1-xGex NW might have promising application in thermoelectrics.