Influence of isotopic content on diamond thermal conductivity

The thermal conductivity of single diamond crystals and CVD diamond films with different C-13 isotope content and different grit size has been analyzed in the framework of Debye's model using Klemens-Callaway's expression for the thermal conductivity. The effect of C-13 isotopes on the diamond thermal conductivity was considered, with allowance made for the earlier adduced assumption that the presence of isotopic impurity, apart from direct resistive effects, results in the activation of the normal phonon scattering processes. As a result, the relaxation time of normal processes turns out to depend on the isotopic concentration. In this case, a good agreement between theory and experiment is observed for the temperature region 10-1000 K. (C) 1999 Elsevier Science S.A. All rights reserved.