Interdependence between strain relaxation and segregation in Au Ni multilayers

We present here a systematic X-ray diffraction study of residual strains in (1 1 1) Au/Ni multilayers prepared by molecular beam epitaxy on (1 0 0) Cu substrates deposited on (1 0 0) Si. The measurement of out-of-plane lattice spacings allows one to extract the unit cell dimension and, by making some assumptions on the strain tensor, to determine the stress and the stress-fret lattice parameter. A striking difference appears between the two constituents of the superlattice, whereas in gold the residual strain appears to be related to the relaxation of the strain as a function of the layer thickness, the nickel parameter is completely controlled by dynamic gold segregation during growth. (C) 1999 Elsevier Science B.V. All rights reserved.