Effect of Morphology on the Phonon Thermal Conductivity in Si/Ge Superlattice Nanowires

We used nonequilibrium molecular dynamics to investigate the role of morphology in the phonon thermal conductivity of 100, 110, 111 and 112-oriented Si/Ge superlattice nanowires at 300 K. Such nanowires with 112 growth direction were found to possess the lowest values of the thermal conductivity [1.6 W/(m center dot K) for a Si and Ge segment thickness of similar to 3 nm] due to the lowest average group velocity and highly effective {113} facets and Si/Ge(112) interface for phonon-surface and phonon-interface scattering, respectively. Comparison with homogeneous and core/shell Si and Ge nanowires showed that the superlattice morphology is the most efficient to suppress the thermal conductivity.