Preparation of ultrathin metal-oxide layers by means of Langmuir-Blodgett films

Langmuir-Blodgett (LB) films of fatty acid salts (Y-stearate, Y-arachidate, Cu-arachidate, Ba-stearate) were thermally oxidized. As a result one obtains ultrathin (a few Å thick) metal-oxide films at the substrate. The surface of the metal-oxide films was found to be rather inhomogeneous. Y and Cu ions remain quantitatively at the substrate despite the heating procedure. A linear dependence between area density of the metal ions in the oxidized films and the number of monolayers of the LB films was observed. The preparation of a mixed metal-oxide film containing Y, Ba, Cu with a given stoichiometry was found to be difficult due to the effect of counter ion exchange. The samples were investigated by means of plasma-desorption and spontaneous-desorption mass spectrometry, by Rutherford back-scattering and electron microscopy.