Papers by Keyword: Surface Segregation

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Authors: Maria Luisa Polignano, Davide Codegoni, Luca Castellano, Stefano Greco, Gabriella Borionetti, Francesco Bonoli, Andreas Nutsch, Roswitha Altmann, Andreas Liebold, Michael Otto, Paolo Monge, Caterina Riva
Abstract: Methods for the analysis of the oxide-silicon interface were compared for their ability to reveal metal segregation at the interface and organic contamination. The impact of these contaminations on surface recombination velocity measurements, on capacitance vs. voltage, conductance vs. voltage and capacitance vs. time measurements and on MOS-DLTS spectra was studied. Niobium-contaminated wafers were used as an example of metal surface segregation, because it was previously shown that niobium is prone to surface segregation. Interface state density measurements obtained by the conductance method showed a limited impact of niobium implantation. Vice versa significant effects were found in MOS-DLTS spectra. For what concerns organic contamination, MOS-DLTS showed the most significant effects from the point-of-view of the intrinsic properties of the silicon oxide - silicon interface, and GOI tests demonstrate a clear impact of the organic contamination on MOS capacitors oxide breakdown events.
Authors: Monika Jenko, M. Godec, H. Viefhaus, Hans Jürgen Grabke
Authors: Gabriel A. López, Eric J. Mittemeijer
Abstract: A systematic investigation of the segregation of Bi at both free surfaces and grain boundaries in Cu, under identical conditions, is reported. The problem of Bi evaporation upon Bi segregation at free surfaces was overcome using a special method for sample preparation. Cu bicrystals containing deliberately made internal cavities at the grain boundary were doped with Bi, annealed at temperatures between 1073 and 1223 K, and broken along the grain boundary in an ultrahigh vacuum chamber for Auger electron spectroscopy. For the first time, the equilibrium surface segregation of Bi in Cu has been measured. The segregation at the free surface was found to be stronger than the segregation at the grain boundary.
Authors: Sangram K. Rath, Manoranjan Patri, Priya Maheshwari, Kathi Sudarshan, Pradeep K. Pujari, Devang V. Khakhar
Abstract: Depth profile of subsurface chemical composition and free volume in segmented polyurethane-urea/clay nanocomposites was studied by angle resolved X-ray photoelectron spectroscopy (ARXPS) and Doppler broadening energy spectroscopy (DBES) using slow positron beam. The ARXPS studies revealed increasing N/C atomic ratio (hard segment to soft segment ratio) at any given depth for the clay loaded samples compared to the neat polymer. DBES study revealed significant microstructure modification with clay loading. Self segregation of hard and soft segments in neat polymer and their interspersing with clay loading was observed from DBES measurements.
Authors: Yoshitaka Nishiyama, Koji Moriguchi, Nobuo Otsuka
Abstract: Laboratory metal dusting test of several Ni binary alloys containing the representative element was conducted in a simulated syngas atmosphere at 650°C for 100h. The Ni alloys containing element belonging to Group 14 and 15 in the periodic series exhibited excellent metal dusting resistance, while those containing Group 13 did not. This behavior was able to be reasonably interpreted from the Blyholder mechanism and the concept of Pauling’s electronegativity.
Authors: Harushige Tsubakino, Atsushi Nogami, Atsushi Yamamoto, Mititaka Terasawa, Tohru Mitamura, Tomoaki Yamanoi, Atsushi Kinomura, Yuji Horino
Authors: M. Fahoume, M. El Khamlichi, C. Baltzinger, C. Burggraf
Authors: Guo Ying Zhang, Gui Li Liu, Jun Shan Bao, Chun Ming Liu, Hui Zhang
Abstract: The energetic study of B effects on the oxidation of γ-TiAl alloys are performed by using the first-principles method based on Density Functional Theory (DFT) in this paper. The surface and interface segregatation of B as well as of the surface adsorption of O are discussed. B is found to preferentially segregat to TiAl subsurface with respect to γ-TiAl bulk. The B segregation at surface decreases oxygen coverage in the initial oxidation process of γ –TiAl alloys, thereby it is beneficial to the decrease of the growth of γ–TiAl alloys oxide film. In the initial oxidation process, oxygen prefers to stay in the vicinity of surface Ti atoms, and B addition is beneficial for the decrease of the growth of A12O3 and TiO2. After the formation of Al2O3 oxide film, B is energetically favoured stayed at interstitial site of α-Al2O3 (0001)/γ-TiAl (111) interface, and enhances the adhesion of this interface.
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