Epitaxial ordered-alloy formation through surface reactions: Al on Ni{0 0 1}

We have studied the products of vacuum deposition of Al on Ni{0 0 1} to compare with Au on Cu{0 0 1}, which is known to develop a surface alloy. Slow vacuum deposition of Al onto unheated Ni{0 0 1} produces partially-ordered one- and two-layer-thin epitaxial Al films. These films have larger interlayer spacing (by about 15%) than the Ni substrate and a substantial disordered component. Anneals of the films, or slow deposition of Al onto a hot Ni{0 0 1} substrate, produce well-crystallized epitaxial films of Ni3Al{0 0 1}. The alloy is not confined to just the surface layer, hence it is not a surface alloy. The thickness of the alloy films can be controlled via the deposition rate of Al and/or the temperature of the Ni substrate. Deposition of Ni on Al{0 0 1}; does not result in ordered alloy formation. © 1988.