Thermal conductivity of epitaxial layers of dilute SiGe alloys

The thermal conductivities of micron-thick epitaxial layers of dilute Si_1-xGeₓ alloys, 2×10^-4<x<0.01, are measured in the temperature range 297<T<5500.3em0exK using time-domain thermoreflectance. These new data are used to test competing models for the strength of phonon scattering by heavy impurity atoms. Even though the mass difference between Ge and Si is much larger than the Si atomic mass, we find that the thermal conductivity of dilute SiGe alloys is adequately described by the scattering strength for point defects derived by perturbation theory by Klemens in 1955.