Ultrafast time-resolved measurements were conducted to investigate scattering mechanism of coherent optical and acoustic phonons in Bi2Te3, Sb2Te3 and Bi2Te3/Sb2Te3 superlattice (SL) films. Strong phonon scatterings in the Bi2Te3/Sb2Te3 SLs are attributed to the interfaces of their hetero-structures. Moreover, decreases of acoustic phonon velocity are observed in SLs, coming from phonon folding and softening. Our results show that both the enhanced interface scattering and the reduced phonon velocity contribute to suppressing the heat transport in SLs.

This content is only available via PDF.
You do not currently have access to this content.