Feb 11, 2020

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 (${{\rm{E}}}_{ad}=4.85\,{\rm{J}}/{{\rm{m}}}^{2}$) is stronger than the Si-Al bond (${{\rm{E}}}_{ad}=3.35\,{\rm{J}}/{{\rm{m}}}^{2}$), 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 (${{\rm{W}}}_{{\rm{sep}}}=1.90\,{\rm{J}}/{\rm{m}}2$) and tension strength ($\gamma =11.55\,{\rm{GPa}}$).


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