PREPARATION AND STRUCTURAL-ANALYSIS OF NICKEL NICKEL-OXIDE MULTILAYERS

Metal/oxide multilayers composed of nickel and nickel oxide were prepared on silicon, fused quartz, and sapphire substrates in an ultrahigh vacuum deposition system using two different methods for growing oxide layers: an oxidation method of metal layering using pulsed oxygen molecular beam, and an evaporation method of NiO with an electron beam evaporator. With x-ray diffraction and calculations using dynamical theory of x-ray reflection, the films prepared via oxidation with more than 60 pulses of oxygen beam at 298 K, and the films prepared by evaporation below 473 K revealed multilayers of Ni/NiOx with artificial periodicity. Multilayers prepared with the oxidation method on silicon and fused quartz have homogeneous bilayers composed of polycrystalline Ni and amorphous-like NiO. In contrast, multilayers prepared by the evaporation method on a sapphire substrate are structurally graded, with layer structures which change gradually from single crystals (1st layer) to polycrystals (last layer). © 1995 American Institute of Physics.