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Epitaxial and polycrystalline orthorhombic GdSi2 films were grown on Si(100) substrates by solid phase reaction between Si and Gd films at different thicknesses of the Gd film . The most important property of these GdSi2/Si interfaces was defect formation. This was investigated by studying the properties of the Schottky barriers by means of current voltage and capacitance–voltage characteristics, deep level transient spectroscopy by double crystal X-ray diffractometry, and transmission electron microscopy. Epitaxial growth of the silicide layer ensured a relatively low interface defect density (about 1010 cm-2), while the non-epitaxial growth induced defects of a much higher density (about 1012 cm-2). The defects generated during the silicide formation are located within a depth of about 10 nm from the GdSi2/Si interface. [ABSTRACT FROM AUTHOR]

A 10-nm-thick gold film was evaporated onto a SiO2/Si(100) substrate and was implanted by Ar+ ions at 40 keV and 1015 at/cm2 dose creating island like Au nanoparticles. An 80-nm-thick gold film was also deposited the onto same substrate and considered as reference.Fe2O3 film was deposited onto the gold nanoparticles and the gold/oxide interface was modeled. The valence band and the structure were measured by means of photoelectron spectroscopy (XPS) and by transmission electron microscopy (TEM), respectively. The catalytic activity was detected by CO oxidation, which was higher after the deposition of Fe2O3 layer onto Au nanoparticles than that on a continuous Au film. This observation was correlated to the nanosize and the redistributed valence band density of states of gold in the Au/Fe2O3 interface. [Copyright &y& Elsevier]

GdSi2 was prepared under ultrahigh vacuum conditions. Prior to processing, a clean interface was produced using diluted HF dipping. It is pointed out that the ‘‘critical temperature’’ for formation published earlier is probably an artifact and correlation between the interface native oxide and the critical temperature is established. [ABSTRACT FROM AUTHOR]

The morphology, electron structure and catalytic activity in CO oxidation of the following samples were compared: an Au/FeOx/SiO2/Si(1 0 0) model sample fabricated by pulsed laser deposition (AuPLD), an Au/Fe2O3 sample prepared by co-precipitation (AuCP) and an Au–Fe/HY (AuHY). It was established that oxygen treatment at 470 K for 1 h increases the rate of CO oxidation on AuPLD and AuCP samples as compared to subsequent hydrogen treatment at 470 K for 1 h, whereas on sample AuHY the effect is reversed. The difference cannot be ascribed to the change in particle size because the average diameter of gold particles is in the range 4–6 nm, which is only slightly modified by oxygen/hydrogen treatments. The difference among the samples cannot be ascribed to surface carbon contamination, because after oxygen treatment the amount of carbon slightly decreases and this cannot account for the activity increase.The major difference lies in the gold/iron oxide interface, which is well developed in the case of AuPLD and AuCP, but it does not exist inside the zeolite in the AuHY sample. In the latter case, the O2− superoxide which is responsible for the enhanced activity cannot be formed. A possible mechanism is given in this paper. [Copyright &y& Elsevier]