Strong effect of electron-phonon interaction on the lattice thermal conductivity in 3C-SiC

Abstract

3C-SiC is a promising semiconductor for many applications where doping and heat dissipation are fundamental parameters in the device design. However, the variation of thermal conductivity with carrier concentration remains to be explored. Using density functional theory, we computed the lattice thermal conductivity in intrinsic and doped 3C-SiC with charge carrier concentrations in the range of ${10}^{17}$ to $10{}^{21}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$. From the calculated phonon dispersion, group velocities, and phonon-phonon scattering rates for undoped bulk 3C-SiC, we obtain a thermal conductivity of 491 W/m K at 300 K. In the case of doped 3C-SiC, we find that the lattice thermal conductivity is strongly reduced at high carrier concentrations. We also predict the effects of electron-phonon interaction (EPI) to be much stronger for hole- than electron-doped material, which is explained by the features of the electronic band structure near the band edges. In the limit of high carrier concentration of $10{}^{21}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$, the thermal conductivity drops by 57% for hole and 32% for electron doping. Our results and analysis provide an in-depth understanding of phonon transport for the design of novel SiC-based electronics.