Spectral Phonon Transport Engineering Using Stacked Superlattice Structures

Abstract

Materials with ultra-low thermal conductivity have important applications in the areas of thermal insulation and energy harvesting. Thermal conductivity of materials can be greatly tuned by the scattering of phonons with miro-/nanostructures. Here, we show a new method to spectrally engineer the phonon transport by using stacked superlattice structures, which is proved by the studies of one-dimensional atomic chain model. The spectral phonon transmission is obtained using atomistic Green’s function approach. The results show that single superlattice can effectively block phonons due to the formed superlattice phonon bandgaps. When multiple superlattices are stacked in series, phonons can be blocked in a much wider spectral range due to the stacked phonon bandgaps. By design, the thermal conductance can be reduced by ten times across a stacked multiple superlattice structure, and the phonon transmission result shows that most phonons can be effectively scattered except for the ones with very low frequency.