Aerosol-Assisted Chemical-Vapour Deposition of Zinc Oxide from Single-Source β-Iminoesterate Precursors

Single-source zinc -iminoesterate precursors have been used for the first time in the aerosol-assisted chemical-vapour deposition (AACVD) of ZnO thin films. Depositions at 450 degrees C on silica-coated glass substrates produced strongly adherent films with excellent coverage of the substrate. The zinc -iminoesterates [Zn(L-1)(2)] (1) and [Zn(L-2)(2)] (2) were synthesised by the reaction between ZnEt2 and 2 equiv. of a synthesised -iminoester ligand CH3C[NHCH(CH3)(2)]CHC(O)OCH2CH3 (L-1) and CH3C(NHCH3)CHC(O)OCH2CH3 (L-2). The synthesised complexes were isolated and characterised by H-1 and C-13 NMR spectroscopy, mass spectrometry and thermal gravitational analysis (TGA). The structures of the compounds were determined by single-crystal X-ray diffraction. The ZnO films deposited from 1 and 2 were analyzed by glancing-angle X-ray powder diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and their optical properties determined by UV/Vis/NIR transmission spectroscopy. These results reveal that the organic ligand attached to the N moiety of the zinc complex has a significant effect on the level of carbon incorporated into the deposited thin film. Upon annealing, highly transparent hexagonal wurtzite ZnO thin films were produced.