We present an analysis of recent thermal-conductivity measurements on crystalline silicon in which the concentration of the ${}^{28}\mathrm{Si}$ isotope has been increased above the natural abundance. We calculate from the phonon Boltzmann equation the change in the conductivity due to a change in isotope concentration. The conductivity change is evaluated numerically using a realistic model of the lattice dynamics of silicon.

• Received 8 May 1998

DOI:https://doi.org/10.1103/PhysRevB.59.10105