Study of thermomechanical properties of Si∕SiGe superlattices using femtosecond transient thermoreflectance technique

Abstract

Using a Femtosecond Transient Thermoreflectance (FTT) technique, we studied the thermomechanical properties of two Si∕SiGe superlattices. A theoretical model is presented which agrees well with the experimental results and allows us to determine the cross-plan thermal conductivity of the superlattices at room temperature. We also show that, from the experimental curve, we can extract the thickness of the metallic film, the longitudinal sound velocity and the refractive index of the superlattice using acoustic echoes and Brillouin oscillation data.