Tris(beta-ketoiminate) Aluminium(III) Compounds as Aluminium Oxide Precursors

Precursor design is the crucial step in tailoring the deposition profile towards a multitude of functional materials. Most commercially available aluminium oxide precursors require high processing temperatures (> 500?). Herein, we report the tuning of the decomposition profile (200-350 ?) of a range of octahedrally coordinated tris(beta-ketoiminate) aluminium complexes of the type [Al(MeCN(R)CHC=OMe)(3)], by varying the R substituents in the ligands. The complexes are derived from the reaction of trimethylamine alane (TMAA) and a series of N-substituted beta-ketoiminate ligands (R-acnacH, R=Me, Et, Pr-i, Ph) with varying R-substituents sizes. When the more sterically encumbered ligand (R=Mes) was used, the Al atom became five-coordinate, therefore representing the threshold to octahedral coordination around the metal in these type of compounds, which, consequently, lead to a change of decomposition profile. The resulting compounds have been characterised by NMR spectroscopy, mass spectrometry, elemental analysis and single crystal X-ray diffraction. [Al(MeCN(Me)CHC=OMe)(3)] has been used as a single source precursor for the deposition of Al2O3. Thin films were deposited via aerosol assisted chemical vapour deposition (AACVD), with toluene as the solvent, and were analysed using SEM, EDX and XPS.