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We have correlated electrical measurements and transmission electron microscopy observations of ultrathin antimony films. The obtained results allow us to understand the crystallization of antimony. It seems that, at room temperature, the critical thickness below which no complete crystallization is possible corresponds to the percolation threshold.

The systematic study of the first stages of antimony growth on amorphous carbon substrates is inhibited by the oxidation of the deposit during transfer through air from the evaporating chamber to the analysis system. To prevent the oxidation of the deposit, the sample is coated in situ with carbon. Under these conditions, transmission electron microscopy and high resolution transmission electron microscopy show that antimony deposits on amorphous carbon supports are amorphous in the first stages of growth. This work shows for the first time that, even for a very low thickness where antimony is considered amorphous, some crystalline antimony aggregates exist on the support. These aggregates are assumed to act as nucleation centres for the crystallization of continuous antimony films which occurs when the equivalent thickness is larger than a critical thickness.

Indium deposits on amorphous carbon grids have been produced by atomic deposition in a vacuum chamber evacuated at a pressure of 1 × 10 −4 Pa. Deposits of 2 nm thickness corresponding to 7.6 × 10 15 atoms cm −2 appear to be formed from small isolated amorphous aggregates. In situ thermal annealing in a transmission electron microscope induces an amorphous-crystalline phase transformation. A similar phase change caused by the electron beam of the microscope is also observed, at an atomic scale, by high resolution electron microscopy. In both cases the phase obtained after transformation is In 2 O 3 .

The behaviour of silver-magnesium oxide interfaces under ionic bombardment has been studied in various sample configurations: silver thin films deposited on magnesium oxide single crystals or multilayers (AgMgO or MgOAgMgO) deposited on NaCl or KBr single crystals. X-ray diffraction and transmission electron microscopy investigations reveal the polycrystalline nature of the continuous silver deposit in the first configuration and the single-crystalline, epitaxial and discontinuous silver deposit in the multilayer configuration. At room temperature, 100, 500 and 800 keV xenon irradiations induce significant interdiffusion at the silver-magnesium oxide interface. In the MgOAgMgO systems the depth profile of the silver concentration is broadened with the dose: a fluence of 4 × 1015 Xe cm−2 induces a length of silver diffusion of about 10 nm. On epitaxial (100) silver-magnesium oxide interfaces xenon irradiations lead to a transition from isolated silver metallic clusters, via percolation, to a quasi-continuous thin silver film. Optical absorption measurements performed on these bilayers further demonstrate this evolution.

Resume On decrit d'abord la preparation par evaporation grain par grain a partir de supports de tungstene et d'iridium, avec apport d'oxygene pendant le depot. Puis on developpe une methode qui s'est averee tres satisfaisante: elle consiste a deposer successivement TiO 2 par pulverisation cathodique reactive et BaO par evaporation a partir de BaCO 3 avec support en platine, puis a effectuer la synthese thermique de BaTiO 3 sur le substrat d'iridium ou de platine.