Phonon engineered suppression of lattice thermal conductivity in segmented and cross-section modulated silicon nanowires

Abstract

The strong suppression of lattice (phonon) thermal conductivity in segmented nanowires, consisting of acoustically-mismatched materials, as well as in cross-section modulated Si nanowires is theoretically demonstrated using the Born-von Karman and Face-centered Cubic Cell models of lattice vibrations. This effect is explained by the exclusion of the phonon modes trapped in nanowire segments from the heat flow. As a result 3- to 30-fold drop of the phonon heat flux in the 50 – 400 K temperature range is predicted for segmented or cross-section modulated nanowires under consideration.