Thermal conductivity of bulk and nanowire of cubic-SiC from ab initio calculations

Abstract

In this work, we predict the structural, elastic, thermal and thermodynamic properties of alpha-silicon carbide (SiC) using the plane-wave pseudopotential approach to density functional theory (DFT) in the local density approximation (LDA). The lattice thermal conductivity of SiC is calculated using the Slack model and Boltzmann transport equation (BTE). We also provide the thermal conductivity of SiC nanowires and the dependence of the thermal conductivity on the diameter and their orientations. The ground state structural and elastic properties show excellent agreement with the experiments. The calculated phonon dispersion curve shows good agreement with the experimental values measured at room temperature. The thermodynamic properties are studied using quasi-harmonic approximation (QHA), and the predicted properties agree well with the experiment. This study demonstrates the need for including the normal phonon scattering and boundary scattering to evaluate the thermal conductivities at low temperature and is evident from the fact that the thermal conductivity at low temperature predicted by the Slack model is higher compared to the value predicted by the BTE. Our BTE calculation for the bulk SiC agrees well with the known experimental results, and we also provide predictions for the case of SiC in the form of nanowires.