Investigations into the structure, reactivity, and AACVD of aluminium and gallium amidoenoate complexes

Abstract

Amidoenoate (AME = {ethyl-3-(R-amido)but-2-enoate}) complexes of aluminium and gallium, of the type: [AlCl₂(AME^R)] R = iPr (1-Al); [AlCl(AME^R)₂] R = iPr (2-Al), Dip (3-Al); [GaCl₂(AME^R)] R = iPr (1-Ga) and [GaCl(AME^R)₂] R = iPr (2-Ga), Dip (3-Ga), have been synthesised (iPr = isopropyl, Dip = 2,6-diisopropylphenyl). The coordination chemistry of these complexes has been studied in relation to precursor suitability. Investigations into the reactivity of the aluminium and gallium amidoenoate complexes involved reactions with hydride sources including alkali metal hydride salts, alkylsilanes, and magnesium hydride species and magnesium(I) dimers. The isolation of alkyl metal amidoenoate precursors including an aluminium hydride amidoenoate, [AlH(AME^Dip)₂] (4-Al) and dimethyl gallium amidoenoates [GaMe₂(AME^Dip)] (4-Ga), [GaMe₂(AME^iPr)] (5-Ga) concluded the synthetic studies. A selection of the isolated complexes were used as precursors for aerosol assisted chemical vapour deposition (AACVD) at 500 °C. Thin films of either amorphous Al₂O₃ or Ga₂O₃ were deposited and subsequently annealed at 1000 °C to improve the materials’ crystallinity. The films were characterised by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), UV-visible (UV-vis) spectroscopy and energy dispersive X-ray analysis (EDXA).