Importance of interfacial step alignment in hetero-epitaxy and orientation relationships: the case of Ag equilibrated on Ni substrates. Part 1 computer simulations

Molecular dynamics simulations of Ag films equilibrated on Ni have been performed for 12 different Ni substrate orientations. The results show that well-equilibrated films display several different orientation relationships (ORs) depending on the Ni substrate orientation: cube-on-cube, twin, oct-cube, and a series of special ORs that are a consequence of the oct-cube OR that develops on Ni(100). It is found that an important feature displayed by the observed ORs is the alignment of the step edges of the Ag film with those of the Ni substrate at the interface. Such alignment is initiated during film formation, but also tends to produce minimum energy interfaces between film and substrate. This feature of hetero-epitaxy and of the resulting ORs has not previously been emphasized.