Modeling the thermal conductivity of a SiGe segmented nanowire

A Debye model is applied to a simple phonon radiation framework to predict the thermal conductivity of a SiGe segmented nanowire. A gray Matthiessen's rule is used to account for bulk scattering while phonon confinement and wave effects are neglected. When either the diameter D or segment length L is smaller than the bulk phonon mean free path the effective thermal conductivity is reduced significantly. In particular, combining diffuse side walls with the diffuse mismatch interface condition at room temperature the alloy limit of 8.5 W/m-K is surpassed for L<15 nm or D <10 nm.