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M. Fink, J. Laimer, H. Störi, C. Mitterer:
"Influence of hydrogen sulfide addition on the alumina deposition by plasma CVD";
Surface & Coatings Technology, 200 (2005), 360 - 363.

Hard alumina (Al2O3) coatings are usually deposited by chemical vapour deposition (CVD) at temperatures of about 1000 8C. However,
the required temperature can be decreased by activating the process gas by a plasma. The coatings deposited so far by plasma-assisted
chemical vapour deposition (plasma CVD) show an admixture of a- and g-alumina, whereby the a-alumina content in the coating increases
with increasing temperature as well as plasma power.
In the present study the effect of hydrogen sulfide (H2S) addition to the process gas on alumina deposition was investigated. Alumina was
deposited on titanium nitride (TiN) coated boron doped silicon (100) substrates. The coatings were analysed by X-ray diffraction (XRD) for
phase composition, by micro-indentation for hardness, by scanning electron microscopy (SEM) for morphology and by X-ray photoelectron
spectroscopy (XPS) for chemical composition. It turned out that the coating thickness decreased strongly with the distance from the central
gas inlet as in the case without H2S additions. At higher temperatures (800 8C) H2S additions favoured the formation of g-alumina, whereby
at lower temperatures (600 8C) H2S promotes a-alumina formation. No sulphur was found in the alumina coatings.
D 2005 Elsevier B.V. All rights reserved.
PACS: 52.75.Rx; 68.55.Jk; 81.05.Je; 81.15.Gh
Keywords: X-ray diffraction; Direct current; Pulsed; PACVD; Aluminium oxide; Hydrogen sulfide

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