Electronic and mechanical properties of Al (100)/6H-SiC (0001) interfaces: a first-principles study

The electronic and mechanic properties of Al (100)/6H-SiC (0001) interfaces are investigated in detail using the exact first-principles density functional theory calculation. Two types of interfaces, C- and Si-terminated, are considered in this work due to the different atom species at the 6H-SiC (0001) surface. Total energy calculations for these two types of interfaces reveal that the C-terminated Al (100)/6H-SiC (0001) interface has strong interfacial bonds with a large work of adhesion rather than the Si-terminated one. A detailed analysis of the bonding mechanism, hybridization of the surface states and charge transfer reveals the strong covalent character of the bonding for the Al (100)/6H-SiC (0001) reaction interface. By comparing the work of separation of different cleavage surfaces, we find that, for the Al (100)/6H-SiC (0001) interfaces, the fracture tends to occur at the Al-Al bonds, rather than at the C(Si)-Al bonds. Although the C-Al bond (E-ad 4.85 J/m(2)) is stronger than the Si-Al bond (E-ad 3.35 J/m(2)), it is easier to fracture at the Al-Al bond near the C-terminated Al (100)/6H-SiC(0001) interface because of its lower work of separation (W-sep = 1.90 J/m(2)) and tension strength (gamma = 11.55 GPa).