Molecular dynamics study of influence of vacancy types defects on thermal conductivity of β-SiC

A molecular dynamics technique has been used to study the impact of single vacancies and small vacancy clusters/microvoids on thermal conductivity of Si and β-SiC. It is found that single vacancies reduce thermal conductivity more significantly than do microvoids with the same total number of vacancies in the crystal. The vacancy concentration dependence of the relative change of thermal resistivity of both Si and SiC changes from linear at low concentrations to square-root at higher values. In contrast, the dependence on the volume fraction of microvoids switches from square-root at small swelling values to nearly linear dependence at higher swelling. In the case of SiC the results obtained for vacancies and microvoids agree reasonably well with experimental values. The computational results are compared with the commonly used Debye-Callaway model.