Thermal conductivity of symmetrically strained Si/Ge superlattices

Abstract

This paper reports temperature-dependent thermal conductivity measurements in the crossplane direction of symmetrically strained Si/Ge superlattices, and the effect of doping, period thickness and dislocations on the thermal conductivity reduction of Si/Ge superlattices. The Si/Ge superlattices are grown by molecular beam epitaxy on silicon and siliconon-insulator substrates with a graded buffer layer. A differential 3ω method is used to measure the thermal conductivity of the buffer and the superlattices between 80 and 300 K. The thermal conductivity measurement is carried out in conjunction with X-ray and TEM sample characterization. The measured thermal conductivity values of the superlattices are lower than those of their equivalent composition bulk alloys.