Modified series model for cross-plane thermal conductivity of short-period Si/Ge superlattices

Abstract

Superlattices have great application potentials in thermo-electric materials and solid laser techniques. Their complicated heat transport mechanisms due to size effects, multi-interfaces and mini-band are very important issues for the prediction of thermal conductivity. In this paper, the short-period Si/Ge superlattices are investigated by a modified series model based on the Debye-Callaway description. The Lambert Law is used to describe the phonon emission within hemisphere space. In addition, the phonon interface transmission coefficients obtained from the phonon wave packet simulation are incorporated into boundary condition of the model, which removes the fitting parameters in the model. Better agreement with experiment is obtained. The effects of temperature, wavelength-dependent phonon transmission, superlattice periods, as well as the thickness of Ge layer are considered in this paper.