The investigation of thermal properties on multilayer Sb₂Te₃/Au thermoelectric material system with ultra-thin Au interlayers

The manipulation of heat transport across multilayer thin films with metal-semicounductor interfaces is of great interest for thermoelectric material optimization. Here we fabricated Sb₂Te₃/Au multilayer films with different Au thickness by magnetron sputtering. We demonstrated that the thermal conductivity of the system can be facilely manipulated by simply changing the Au layer thickness, where an optimal thickness (5 nm) value exists with the lowest thermal conductivity (∼0.44 Wm^-1K^-1, 44% of the pure Sb₂Te₃ thin film thermal conductivity). It has been proved that the decreased thermal conductivity was mainly attributed to the strong electron-phonon coupling in a metal-nonmetal multilayered system with Au layer thickness larger than 5 nm, where the Two Temperature Model (TTM) predicts the experimental data perfectly. It was also proposed that the grain boundary effect may dominiate the phonon scattering when the Au layer is in a discountinuous form (<5 nm).