Thermal conductivity of superlattices

Abstract

The lattice thermal conductivity of superlattices is shown to depend on a new kind of umklapp scattering process, called a mini-umklapp, associated with the mini-Brillouin zone of the superlattice. Expressions for three-phonon mini-umklapp-scattering matrix elements are obtained for superlattices consisting of lattice-matched simple-cubic layers. The temperature dependence of the thermal conductivity is evaluated using an extension of Callaway's phenomenological model.