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    Formation of Ge nanocrystals and SiGe in PECVD grown SiNx: Ge thin films
    (Elsevier Sci Ltd, 2006) Dana, Aykutlu; Tokay, Serkan; Aydınlı, Atilla
    Formation of Ge nanocrystals in SiNx matrices has been studied using plasma enhanced chemical vapor deposition in both as deposited samples as well as in post-vacuum annealed samples. Low temperature and short duration anneals in vacuum resulted in Ge nanocrystals whereas prolonged anneals at higher temperatures resulted in Ge nanocrystals accompanied with SiGe formation at the SiNx/Si interface. Raman Scattering Spectroscopy was extensively used to track the formation of various phonon modes during the diffusion of Ge through SiNx and into the Si substrate. (C) 2006 Published by Elsevier Ltd.
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    Öğe
    Formation of silicon nanocrystals in sapphire by ion implantation and the origin of visible photoluminescence
    (Amer Inst Physics, 2006) Yerci, Selçuk; Serincan, Uğur; Dogan, İlker; Tokay, Serkan; Genisel, Mucip; Aydınlı, Atilla; Turan, R.
    Silicon nanocrystals, average sizes ranging between 3 and 7 nm, were formed in sapphire matrix by ion implantation and subsequent annealing. Evolution of the nanocrystals was detected by Raman spectroscopy and x-ray diffraction (XRD). Raman spectra display that clusters in the matrix start to form nanocrystalline structures at annealing temperatures as low as 800 degrees C in samples with high dose Si implantation. The onset temperature of crystallization increases with decreasing dose. Raman spectroscopy and XRD reveal gradual transformation of Si clusters into crystalline form. Visible photoluminescence band appears following implantation and its intensity increases with subsequent annealing process. While the center of the peak does not shift, the intensity of the peak decreases with increasing dose. The origin of the observed photoluminescence is discussed in terms of radiation induced defects in the sapphire matrix. (c) 2006 American Institute of Physics.