SiC thermal conductivity: calculation of the isotope effect from first principles

Abstract

The thermal conductivity temperature dependence kappa(T) of a hexagonal 2H-SiC silicon carbide crystal was calculated using the first-principle approach for the orientation of the heat flux in the basal plane and along the hexagonal axis c in the temperature range from 100 to 500 K. The effect of silicon and carbon isotopic disorder on thermal conductivity is considered. It was found that, at a temperature of 300 K, the thermal conductivity of isotopically pure 2H-SiC containing 100% 28Si and 100% 12C is higher by 15.2% and 12.4% for directions along and across the basal plane, respectively, than that of crystals with a natural composition of silicon and carbon isotopes. For crystals with a natural mixture of carbon isotopes textnatC, the isotope effect for silicon is 14.5% and 11.9% for these directions. Keywords: single crystal, thermal conductivity, silicon carbide, first principle calculation.