Ag organisation on Ni(1 1 1) surface

The first stages of growth and organisation of a silver atom deposit on a nickel (1 1 1) surface have been investigated by scanning tunnelling microscopy. For a coverage lower than two monolayers and depending on the surface defect content, deposition at room temperature leads to a random distribution of small Ag islands on the surface, while growth at 400 K shows the Ag trend to form islands mainly attached to the substrate step edges. When the sample is annealed at 525 K, Ag organises in stripes decorating the steps edges and in islands located in the middle of the large terraces, with a thickness of one or two monolayers. Further annealing at 675 K completely reorganises the surface morphology with a strong demixing: Ag uniformly covers part of the substrate terraces, and leaves large bare Ni areas. At this stage, the ultra-thin film always presents a thickness of two monolayers.