First-principles studies of effects of layer stacking, opposite atoms, and stacking order on two-photon absorption of two-dimensional layered silicon carbide

Based on the first-principles calculations of monolayer, bilayer, and trilayer two-dimensional layered silicon carbides, we show that layer stacking, opposite atoms, and stacking order slightly influence the transverse two-photon absorption coefficient (beta(a)) but significantly change the longitudinal two-photon absorption coefficient (beta(c)). From monolayer to few-layer, the values of beta(c) exhibit large enhancement owing to the effect of layer stacking, which not only increases the two-photon absorptive pathways but also enlarges the contribution of a single two-photon absorptive pathway to beta(c). The effect of opposite atoms leads to different beta(c) profiles owing to different van der Waals interactions. The effect of stacking order increases the number of allowed two-photon absorptive pathways from ABA to ABC stacking but would not change the magnitude of TPA coefficients. For the few-layer configurations, the interlayer TPA transition channels make significant contributions to the total TPA process. Finally, we also show that two-photon absorption spectra are more suitable than one-photon absorption spectra for identifying different two-dimensional layered silicon carbides in terms of line shape and peak positions.