Partially coherent phonon heat conduction in superlattices

Abstract

In this paper, the phonon thermal conductivity of semiconductor superlattices is calculated with the use of a modified lattice dynamics model, in which an imaginary wave vector is added. The mean free path caused by diffuse interface scattering is included in the imaginary wave vector. This model combines the effects of phonon confinement and diffuse interface scattering on the thermal conductivity in superlattices, and is applicable to phonon transport in the partially coherent regime, where bulk and superlattice phonon modes mix up. The theoretical results for the GaAs/AlAs superlattices are compared with the experimental data. The period thickness dependence and temperature dependence of the thermal conductivity in the GaAs/AlAs superlattices can be well explained by this model.