First-principles study on edge-edge interactions of bilayer zigzag SiC nanoribbons

Abstract We have identified a complex interplay of van der Waals, coulombic, and direct edge-to-edge covalent interactions as key factors in determining the stability of bilayer zigzag SiC nanoribbons (ZSiCNRs). The Si–Si edge of the homo-AA-stacked ZSiCNR displays a unique bond angle, indicative of sp 3 -like covalent bonds. In contrast, the C–C edge shows a flat structure, suggesting a formation of the pseudo-chemical bonding between p z orbitals at the edge like bilayer graphene NRs. The homo-AA-stacked ZSiCNR is nonmagnetic and metallic, although the monolayer ZSiCNR exhibits magnetic properties due to spin-polarized p z orbitals localized at the edge Si and C atoms. In contrast, the hetero-AA-stacked ZSiCNR is more stable than the homo one and is indicative of semiconductor properties with a finite band gap, since the topology of the edge states originating from p z orbitals is no longer preserved.