First-principles study of the adhesive and mechanical properties of the O-terminated α-Al₂O₃(0001)/Cu(111) interfaces

Abstract

Adhesive and mechanical properties of the O-terminated (O-rich) α-Al₂O₃(0001)/Cu(111) interface have been examined by the first-principles pseudopotential method. Strong Cu–O covalent and ionic interactions exist, such as Cu3d–O2p hybridization and substantial electron transfer from Cu to O, which result in larger adhesive energy, greater tensile strength and larger interfacial Young's moduli than the Al-terminated (stoichiometric) interface with electrostatic–image and Cu–Al hybridization interactions. Substantial effects of interfacial Cu–O coordination are also present. Changes in the interface electronic structure for cleavage have been examined. Cu–O interlayer potential curves have been analyzed using the universal binding energy relation and compared with Cu–Al and Cu–Cu curves, which is valuable for the development of effective interatomic potentials in large-scale simulations.

Acknowledgements

The authors thank Dr T. Sasaki, Dr T. Mizoguchi, Professor K. Matsunaga, and Professor Y. Ikuhara for fruitful discussions on experimental and theoretical analyses of the Al₂O₃(0001)/Cu(111) interface. They are grateful to Dr S. V. Dmitriev, Dr Y. Hangai, Professor N. Yoshikawa, Dr M. Hasegawa and Professor Y. Kagawa for discussions on the potential development and mechanical properties. They also thank Professor W. Zhang for discussions on the atomic models. This work was supported by New Energy and Industrial Technology Development Organization (NEDO) as Nanostructure Coating Project. Computations were supported by Tsukuba Advanced Computing Center (TACC) of AIST.