Unveiling the interface characteristics of diamond/Al interface: First-principles calculations and experiments

In this work, both first-principles calculations and experimental results revealed different interface characteristics of (111) and (100) diamond/Al interfaces. Tensile simulations were applied to examine the fracture behavior of diamond(111)/Al(111), diamond(100)/Al(111), and diamond(100)/Al₄C₃(003) interfaces. The results demonstrate that the work of adhesion and the tendency for Al-C bond formation are significantly greater at the diamond(100)/Al(111) compared to the the diamond(111)/Al(111) interface. The growth morphology arising from reactions between Al and various diamond crystal planes is closely linked to the distinct surface characteristics of the diamond. The diamond(100)/Al₄C₃(003)-C terminal interface shows the highest work of adhesion due to the synergistic effects of C–C and Al-C bonding, as well as the reconstruction of diamond C atoms. During the tensile calculations, multilayer relaxation occurred on the Al₄C₃(003) side for diamond(100)/Al₄C₃(003)-C terminal interface, with the highest ultimate tensile strength. While the Al atoms near the diamond(111)/Al(111) interface undergoing a clean, cohesive fracture at a tensile strain of 16 %, making it the weakest point prone to failure. The theoretical tensile strength of the diamond(100)/Al₄C₃(003)-C terminal interface is about 2.5 times that of the diamond(111)/Al(111) interface. Our work unveils the underlying crystal orientation-dependent growth of Al₄C₃ and the fracture mechanism of diamond/Al by first-principles calculations and experiments.