Atomic Relaxation of Epitaxial NiAl (001): The Strain Effect

We have studied the interfacial behavior of coherent NiAl intermetallic layers on III-V type semiconductor substrates via computer simulations. The embedded atom method (EAM) was applied to molecular statics simulations. Atoms near interfaces showed abnormal relaxations while those in the middle of layers relaxed almost uniformly. With an application of interfacial strain, the amount of relaxation perpendicular to the surface changed substantially. However, the estimates by the EAM deviated appreciably from values predicted by the linear elastic theory if the interfacial misfit strain exceeds -2% or +3% under compressive or tensile strain, respectively. This difference is expected to affect not only the electronic and magnetic properties of a device but the stability of the epitaxial layers.

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