First principles simulations of phonon-assisted indirect optical properties of common SiC polytypes

Silicon carbide (SiC) is an important indirect-gap semiconductor used in many electronic/optoelectronic devices. Although being a well-studied material, first principles simulation of its phonon-assisted optical properties, dominating near the absorption onset, remains a challenge due to the high computational cost and lack of theoretical tools. In our study, we apply density functional perturbation theory and maximally localized Wannier functions to evaluate and interpolate the electron-phonon coupling matrix elements in order to investigate phonon-assisted optical absorption in five common SiC polytypes. We show that combined with the GW/Bethe-Salpeter equation approach, our simulated indirect optical spectra agree well with experimental measurements. Our work provides valuable foundation for the further theoretical investigation of phonon-mediated optical properties such as photoluminescence, as well as guidance on potential optoelectronic applications of the different polytypes.