Thermal Conductivity Anisotropy in Phonon Transport of Bi2Te3/Bi0.5Sb1.5Te3 Superlattice Film

Abstract

Nanoscale superlattice thin films generally exhibit larger phonon and electron scattering at the interface in the direction of the cross-plane of the samples. Therefore, it is very important to further detailed study of espe-cially phonon transport of the superlattice films. Here, we report temperature dependent thermal conductivity anisotropy in phonon transport of Bi2Te3/Bi0.5Sb1.5Te3 superlattice thin films at 200-500 K. Thermal conductiv-ity of these thin films for in-and cross-plane thermal conductivities were determined to be approximately 0.74 and 0.4 W m(-1) K-1 at 200-500 K, respectively, clearly indicating similar to 185% suppression in-and cross-plane thermal conductivities of the superlattice thin films with a large anisotropic behavior. Such large anisotropy in the thermal conductivity can be attributed to enhanced phonon scattering occurring at the interface of the Bi2Te3 and Bi0.5Sb1.5Te3 layer.