Analysis of Thermal Conductivity-A Reply

The criticism of the assignment of a ${T}^{3}$ temperature dependence to the relaxation time due to longitudinal three-phonon interactions and the subsequent effect of this assignment on the temperature dependence of the lattice thermal conductivity of silicon, germanium, and gallium arsenide is considered. It is asserted that the reasons for the initial assignment have not been shown to be invalid, nor has a better assignment been established. However, the criticism of the statement that the transverse phonons can account for a majority of the heat flow is valid because this conclusion has not been adequately tested.