Bonding at the SiC-Graphite Interface: Quantum Mechanical Calculations

SiC/graphite interfaces are critical in high-temperature structural and electronic applications, but the atomic-scale origins of adhesion and electronic coupling remain insufficiently resolved. We employ first-principles density functional theory (DFT) to investigate the structural and electronic properties of SiC/graphite interfaces, focusing on interfacial bonding and orbital hybridization. Interfaces between 3C-SiC(111)/graphite(0001) and 4H/6H-SiC(0001)/graphite(0001) were compared. The hexagonality of the SiC polytype has little effect on the interfacial energetics; instead, surface termination primarily determines the stability order. For Si-terminated surfaces, stacking sequence effects are minor, and the calculated formation energies (−1.06 to −0.75 J m⁻²) indicate sp³-like Si-C covalent bonding with partial rehybridization of interfacial carbon. On the other hand, C-terminated interfaces, with formation energies of −0.45 to −0.29 J m⁻², show weaker π-type bonding from pz-pz overlap. These results clarify how surface termination governs SiC/graphite adhesion and suggest that 4H/6H polytype stability can be achieved at lower processing temperatures.