Papers by Author: Giancarlo Salviati

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Authors: Sergio Pizzini, Simona Binetti, Alessia Le Donne, E. Leoni, Maurizio Acciarri, Giancarlo Salviati, L. Lazzarini
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Authors: Sathish Chander Dhanabalan, Marco Negri, Francesca Rossi, Giovanni Attolini, Marco Campanini, Filippo Fabbri, Matteo Bosi, Giancarlo Salviati
Abstract: Cubic silicon carbide - silicon dioxide core-shell nanowires have been synthesized in a thermal CVD system from carbon monoxide on silicon substrate. Using a non-ionic surfactant during the coating process of the substrate by the catalyst, the uniformity of the catalytic layer was improved, resulting in a more uniform nanowires growth. It is demonstrated that the core diameter is strongly correlated with the precursor concentration.
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Authors: Filippo Fabbri, Francesca Rossi, Giovanni Attolini, Matteo Bosi, Giancarlo Salviati, Salvatore Iannotta, L. Aversa, R. Verucchi, M. Nardi, Naoki Fukata, Benjamin Dierre, Takashi Sekiguchi
Abstract: In this work we report the enhancement of the 3C-SiC band edge luminescence induced by the SiO2 shell in SiC/SiO2 core/shell nanowires (NWs) system. We demonstrate that the shell enhances the SiC near band edge luminescence and we argue the formation of a type-I quantum well between the SiC core and the SiO2 shell, with the consequent injection of carriers from the larger band-gap shell to the narrower band-gap core.
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Authors: Mikael Syväjärvi, L. Nasi, Gholam Reza Yazdi, Giancarlo Salviati, M. Izadifard, I.A. Buyanova, W.M. Chen, Rositza Yakimova
Abstract: Ferromagnetic phases in as-grown SiC have been studied. An interpretation about the formation based on details of the phase appearance in the layers from optical microscopy, AFM, and TEM investigations is related to the growth. Some phases were found to have a nucleation at the edge of the phase and detailed TEM investigations show that the phases have an increased grain density at the edge while the main part of the phase is monocrystalline.
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Authors: Antonio Castaldini, Anna Cavallini, L. Polenta, Giancarlo Salviati
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Authors: Giovanni Attolini, Francesca Rossi, Filippo Fabbri, Giancarlo Salviati, Matteo Bosi, Bernard Enrico Watts
Abstract: β-SiC/SiO2 core-shell NWs have been synthesized on patterned silicon wafers in a CVD system, using carbon oxide as single precursor and nickel nitrate as catalytic element, in nitrogen or argon atmosphere at 1100°C. The coaxial structure and the crystallinity of the NW core are examined by (scanning) transmission electron microscopy. The patterning of the substrate allows to grow NWs in selected areas only, as imaged by SEM. Cathodoluminescence (CL) panchromatic images of the same areas point out that the light emitted under electron excitation is localized only in the area covered with NWs. The room-temperature CL spectrum has three different components peaked at 2.45 eV, related to the 3C-SiC near-band-edge emission, and at 2.75 and 3.75 eV, that are induced by the triplet and singlet states of oxygen-deficiency centers ODC(II) in silicon dioxide shell.
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Authors: Giovanni Attolini, Matteo Bosi, Francesca Rossi, Bernard Enrico Watts, Giancarlo Salviati, Gábor Battistig, László Dobos, Béla Pécz
Abstract: 3C-SiC films were grown on Si by VPE using CBr4 as the carbon source, at temperatures ranging between 1100 to 1250°C. XRD, TEM, AFM, and SEM results indicate that the epitaxy proceeds as a 3D growth of uncoalesced islands at low temperature, whereas a continuous layer with hillocks on top is obtained above 1200°C. The shape and faceting of the islands are analyzed by AFM, showing (311) preferred facets.
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Authors: Paola Lagonegro, Matteo Bosi, Giovanni Attolini, Marco Negri, Sathish Chander Dhanabalan, Francesca Rossi, Francesco Boschi, P.P. Lupo, Tullo Besagni, Giancarlo Salviati
Abstract: We report on the synthesis of SiC nanowires (NWs) using iron as catalyst. The NWs were grown on silicon substrate by vapour-liquid-solid (VLS) mechanism with propane and silane as precursors, both 3% diluted in hydrogen, and hydrogen as carrier gas. The growth temperature was 1250°C, to reach the eutectic values of the Si-Fe alloy and to permit the VLS mechanism. The as-grown SiC nanowires were characterized by scanning and transmission electron microscopy. The nanowires are from 30 to 100 nm in diameter and several μm in length, with <111> growth direction.
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Authors: Francesca Rossi, Filippo Fabbri, Giovanni Attolini, Matteo Bosi, Bernard Enrico Watts, Giancarlo Salviati
Abstract: -SiC and -SiC/SiO2 core-shell nanowires (NWs) grown on silicon substrates by three different processes, based on the use of i) carbon monoxide, ii) silane with propane and iii) carbon tetrachloride precursors, are analysed by structural and optical techniques. Spectroscopic cathodoluminescence studies show a luminescence enhancement in core-shell structures, ascribed to an effective role of the shell as both carrier injecting barrier and passivation layer. In NWs grown using CCl4 precursor, a peculiar luminescence with dominant red component at about 2 eV has been detected and ascribed to point defects related to an unintentional oxygen incorporation.
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Authors: Franca Albertini, Antonio Paoluzi, L. Pareti, L. Nasi, Giancarlo Salviati, Gianluca Calestani
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