▎ 摘　　要

The graphene-like silicon carbide (SiC) has attracted much attention recently owing to its potential application in optoelectric devices. In this work, we have theoretically investigated the excitonic effects on the dielectric constants [epsilon(omega)] of monolayer (ML-) and bilayer (BL-) SiC using the first principle calculations with solving the Bethe-Salpeter equation. The Tran-Blaha modified Becke-Johnson exchange potential combined with the Perdew and Wang correlation potential is used to overcome the underestimate of bandgap. Within the independent particle approximation, BL-SiC not only has the same intralayer pi -> pi* transition in the transverse epsilon(omega) as ML-SiC but also has an interlayer pi -> pi* transition in the longitudinal epsilon(omega). The excitonic effects dramatically change the absorption spectra of two polarization directions (transverse and longitudinal). For the transverse epsilon(omega), BL-SiC has a similar excitonic absorption profile to ML-SiC but shows a blue-shift relative to ML-SiC and an apparent decrease in the binding energy of bright exciton. For the longitudinal epsilon(omega), ML-SiC has a bright exciton with a large binding energy of 1.87 eV related to the sigma -> pi* transition band, and BL-SiC has a bright exciton with a small binding energy of 0.41 eV related to the interlayer pi -> pi* transition. (C) 2017 Elsevier B.V. All rights reserved.