PROPERTIES OF ULTRATHIN SILVER LAYERS ON THE NI(111) FACE

Growth and annealing of silver films on the Ni(111) face were investigated with the AES, LEED, directional AES (DAES) and directional elastic peak electron spectroscopy (DEPES) in the temperature range from RT up to desorption temperature. At room temperature kinetics of Auger peak heights h(Ag) and h(Ni) indicate the growth of the first silver layer up to a coverage theta similar or equal to 0.7 ML. Then, the second and first layers grow simultaneously. At theta = 1.4 ML the first layer is completed. At elevated temperatures a bilayer growth is observed and, for coverages theta > 3 ML, the reconstruction of the silver layer takes place. For theta similar or equal to 1 ML, LEED patterns characteristic of the p(1X1) silver structure with the silver lattice constant are visible together with the Ni(111) pattern. For higher coverages only the Ag(111) pattern is visible. This means that the nickel substrate is effectively covered with silver when theta > 2 ML. DEPES polar profiles indicate that two orientations of the silver (111) layer ([1 $($) over bar$$ 1 $($) over bar$$ 21](111)Ag parallel to[1 $($) over bar$$ 21](111)Ni and [<($$)over bar>112](111)Ag parallel to[1 $($) over bar$$ 21](111)Ni) occur simultaneously. During annealing at higher and higher temperatures, the silver layer with a thickness of a few ML starts to diminish at temperatures of 890-935 K corresponding to the low-temperature end of the TDS peak tail, and disappears completely after several hundred seconds of such annealing.