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    Optical Properties of Silicon Nanowires Fabricated by Environment-Friendly Chemistry
    (New York, NY [u.a.] : Springer, 2016) Gonchar, Kirill A.; Zubairova, Alsu A.; Schleusener, Alexander; Osminkina, Liubov A.; Sivakov, Vladimir
    Silicon nanowires (SiNWs) were fabricated by metal-assisted chemical etching (MACE) where hydrofluoric acid (HF), which is typically used in this method, was changed into ammonium fluoride (NH4F). The structure and optical properties of the obtained SiNWs were investigated in details. The length of the SiNW arrays is about 2 μm for 5 min of etching, and the mean diameter of the SiNWs is between 50 and 200 nm. The formed SiNWs demonstrate a strong decrease of the total reflectance near 5-15 % in the spectral region λ < 1 μm in comparison to crystalline silicon (c-Si) substrate. The interband photoluminescence (PL) and Raman scattering intensities increase strongly for SiNWs in comparison with the corresponding values of the c-Si substrate. These effects can be interpreted as an increase of the excitation intensity of SiNWs due to the strong light scattering and the partial light localization in an inhomogeneous optical medium. Along with the interband PL was also detected the PL of SiNWs in the spectral region of 500-1100 nm with a maximum at 750 nm, which can be explained by the radiative recombination of excitons in small Si nanocrystals at nanowire sidewalls in terms of a quantum confinement model. So SiNWs, which are fabricated by environment-friendly chemistry, have a great potential for use in photovoltaic and photonics applications.
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    XPS investigations of MOCVD tin oxide thin layers on Si nanowires array
    (Amsterdam : Elsevier, 2018) Turishchev, S.Yu.; Chuvenkova, Olga; Parinova, V.E.; Koyuda, D.A.; Chumakov, Ratibor G.; Presselt, Martin; Schleusener, Alexander; Sivakov, Vladimir
    Tin oxide thin layers were grown by metal-organic chemical vapor deposition technique on the top-down nanostructured silicon nanowires array obtained by metal-assisted wet-chemical technique from single crystalline silicon wafers. The composition of the formed layers were studied by high-resolution X-ray photoelectron spectroscopy of tin (Sn 3d) and oxygen (O 1 s) atoms core levels. The ion beam etching was applied to study the layers depth composition profiles. The composition studies of grown tin oxide layers is shown that the surface of layers contains tin dioxide, but the deeper part contains intermediate tin dioxide and metallic tin phases.
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    Synchrotron studies of top-down grown silicon nanowires
    (Amsterdam : Elsevier, 2018) Turishchev, S.Yu.; Parinova, V.E.; Nesterov, D.N.; Koyuda, D.A.; Sivakov, Vladimir; Schleusener, Alexander; Terekhov, V.A.
    Morphology of the top-down grown silicon nanowires obtained by metal-assisted wet-chemical approach on silicon substrates with different resistance were studied by scanning electron microscopy. Obtained arrays of compact grown Si nanowires were a subject for the high resolution electronic structures studies by X-ray absorption near edge structure technique performed with the usage of high intensity synchrotron radiation of the SRC storage ring of the University of Wisconsin-Madison. The different oxidation rates were found by investigation of silicon atoms local surrounding specificity of the highly developed surface and near surface layer that is not exceeded 70 nm. Flexibility of the wires arrays surface morphology and its composition is demonstrated allowing smoothly form necessary surface oxidation rate and using Si nanowires as a useful matrixes for a wide range of further functionalization.