J. Phys. IV France 10 (2000) Pr2-35-Pr2-42
Preparation and characterization of some alumosiloxanes as single-source MOCVD precursors for aluminosilicate coatingsS.M. Zemskova, J.A. Haynes, T.M. Besmann, R.D. Hunt, D.B. Beach and V.N. Golovlev
Oak Ridge National Laboratory, P.O. Box 2008, 1 Bethel Valley Road, Oak Ridge, TN 37831-6063, U.S.A.
Alumosiloxanes [Al(OSiMe3)3]2, (Me3SiO)2Al[OSi(OBu-t)3], [(acac)Al(OSiMe3)2]2, (Ox)Al[OSi(OBu-t)3]2, (Me=CH3 ; Bu-t= t-C4H9 ; acac = C5H7O2 ; Ox = C9H6NO) have been synthesized and their thermal properties have been studied by thermogravimetric analysis in Ar over the temperature range of 25-500°C. The compounds [Al(OSiMe3)3]2 and [(acac)Al(OSiMe3)2]2 showed substantial volatility during heating regardless of their dimeric structures in the solid state ; while the other compounds were largely decomposed under the same conditions. Therefore, [Al(OSiMe3)3]2 and [(acac)Al(OSiMe3)2]2 have been chosen as prospective precursors for the MOCVD of aluminosilicate coatings. Investigation of these compounds by laser mass-spectrometry (laser excitation at 355nm) has shown that the decomposition pathway proceeds through the formation of a number of heavy species originating from dimeric [>Al(OSi)2>Al<] fragments of [Al(OSiMe3)3]2 and [(acac)Al(OSiMe3)2]2 molecules and silicon-containing light species of m/z 52 (C2Si) and 55(C2H3Si) originating from OSiMe3 ligands. Initial experiments have been carried out on the deposition of aluminosilicate coatings on silicon carbide from the precursors described.
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