Abstract:
Clear understanding of phonon properties in nanostructures is instrumental in design of novel
thermoelectric materials [1-3]. Crystalline/amorphous superlattices (CASLs) consisting of
alternated crystalline and amorphous layers are promising in tailoring the thermoelectric
properties because they can be made of materials with distinctly different physical and
chemical properties. Here we report on theoretical study of phonon thermal transport in c-
Si/a-SiO2 CASLs, which remain less explored in the literature [4]. Comparing equations for
lattice thermal conductivity within linearized Boltzmann transport equation [5-6] and Allen-
Feldman theory of diffusive thermal transport [7-8] we have obtained an expression for the
rate of diffusion of lattice vibrations in a-SiO2 layers. The obtained expression is parameter-
free and can be used for a wide range of amorphous materials. The performed theoretical study have showed, that heat transport in c-Si/a-SiO2 CASLs is strongly suppressed as
compared to purely crystalline c-Si/c-SiO2 superlattices. Owing to the reduced lattice thermal
conductivity, we conclude that c-Si/a-SiO2 CASLs show promise for thermoelectric
applications.
