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Title:
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Oxidation and crystallization behavior of luminescent Eu-doped Calcium Silicon Nitride thin films during rapid thermal processing
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Author(s):
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Jong, de M.; Enter, V.E. van; Schuring, E.W.; Kolk, E. van der
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Published by:
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Publication date:
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ECN
Environment & Energy Engineering
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19-5-2015
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ECN report number:
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Document type:
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ECN-W--15-013
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Article (scientific)
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Number of pages:
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Full text:
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24
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Download PDF
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Published in: Thin Solid Films (Elsevier), , 2015, Vol., p.-.
Abstract:
Luminescent thin films were fabricated on silicon wafers using reactive magnetron sputtering of Ca, Si and Eu in Ar/N2 atmosphere. In order to activate the luminescence, the as-deposited nitride films were heated to 1100oC by a rapid thermal processing (RTP) treatment. X-ray diffraction (XRD) measurements reveal the crystal phases that form during RTP treatment. By recording scanning electron microscopy (SEM) images of the surface and the cross-section of the film at different radial locations, the formation of different layers with a thickness depending on the radial position is revealed. Energy dispersive x-ray spectroscopy (EDX) analysis of these cross-sections reveals the formation of an oxide top layer and a nitride bottom layer. The thickness of the top layer increases as a function of radial position on the substrate and the thickness of the bottom layer decreases accordingly. The observation of different 4f 65d1 ? 4f 7 Eu2+ luminescence emission bands at different radial positions correspond to divalent Eu doped Ca3Si2O4N2, Ca2SiO4 and CaSiO3, which is in agreement with the phases identified by XRD analysis. A mechanism for the observed oxidation process of the nitride films is proposed that consists of a stepwise oxidation from the as-deposited amorphous nitride state to crystalline Ca3Si2O4N2, to Ca2SiO4 and finally CaSiO3. The oxidation rate and final state of oxidation show a strong temperature-time dependency during anneal treatment.
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