Growth and morphology of Ni(111)/Re(0001) ultrathin films: An in-situ study using scanning tunneling microscopy

A scanning tunneling microscopy (STM) study is presented for the growth of Ni films on Re (0001) at 300 K. A Ni(111) wedge with a slope of 5 ML cm(-1) was prepared under identical conditions. STM images were recorded in ultrahigh vacuum at 300 K on areas of the wedge with constant coverage. Nearly ideal two-dimensional growth is observed for the first three layers. The second layer grows only after the first layer is 90% complete. For films with thicknesses 2 < d less than or equal to 9 ML, a perfect hexagonal dislocation network which matches the known 9/10 misfit of Ni(111) with respect to Re(0001) is observed across 600 x 600 nm(2) images. The corrugation of similar to 0.3 Angstrom, observed at 3 ML, decreases with an increasing number of layers and vanishes completely around 10 ML. The dislocation pattern does not seem to be disturbed by the presence of monoatomic steps. A characteristic change in the pattern of the dislocation network is observed from 1 to 3 ML. (C) 1997 Elsevier Science B.V.