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Aerosol assisted chemical vapour deposition (AACVD) has been used to deposit thin films of ZnO from the single-source precursor [Zn(OC(Me)CHC(Me)N( i Pr)) 2 ] ( 1 ) affording highly transparent (>80%) and conductive films (sheet resistance ∼70 KΩ/sq). Extension of this AACVD method whereby related precursors of the type, [R 2 M(OC(Me)CHC(Me)N( i Pr))] (R = Et, M = Al ( 2 ); R = Me, M = Ga ( 3 )), isolated as oils, were added to the precursor solution allowed for the deposition of aluminium- and gallium-doped ZnO (AZO and GZO) films, respectively. Complexes 1 – 3 were characterised by elemental analysis, NMR and mass spectrometry. Films were deposited in under 30 min at 400 °C, from CH 2 Cl 2 /toluene solutions with a N 2 carrier gas. Herein we report the bulk resistivity, ρ , of AZO (0.252 Ω cm) and GZO (0.756 Ω cm) films deposited from this novel approach. All the films transparency exceeded 80% in the visible, X-ray diffraction (XRD) showed all films to crystallise in the wurtzite phase whilst X-ray photoemission spectroscopy (XPS) confirmed the presence of the Al and Ga dopants in the films, and highlighted the low C-contamination (<5%) this route offers. Investigation of a mechanism analogous to the Kirkendall effect confirmed that heating of GZO films at 1000 °C produced the spinel structure GaZn 2 O 4 . [ABSTRACT FROM AUTHOR]

The use of zinc triflate (trifluoromethanesulfonate), [Zn(OTf) 2 ] as a precursor in the aerosol assisted chemical vapour deposition of zinc oxide thin films is described. Aluminum doped zinc oxide (AZO) thin films are also shown to be deposited when aluminum acetylacetonate [Al(acac) 3 ] was introduced into the precursor solution, illustrating the versatility of this system. Film characterization techniques include glancing angle X-ray powder diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and optical and electrical measurements. AZO films with an Al content of 7 at.% were found to have favourable transparent conducting oxide properties with simultaneous high transparency (> 80%) in the visible light region and a low electrical resistivity (1.96 × 10 − 3 Ω cm). [ABSTRACT FROM AUTHOR]

A conventional solution-based route to a cyclic trimeric organozinc compound [{Zn(Et)( β-diketonate)}3] ( β-diketonate=OC(OMe)CHC(Me)O, 1) is described, with 1 structurally characterized for the first time. The ligand selection of bidentate β-diketonates is shown to be key to isolating a cyclic trimer. Additional reaction of β-diketonates with diethyl zinc were spectroscopically characterized as compounds of the type [{Zn(Et)( β-diketonate)} n] ( β-diketonate=OC(Me)CHC(Me)O, 2, OC(O tBu)CHC(Me)O, 3). Further studies have shown that selective oxidation of these species produces cubanes of the general formula [{Zn(OC(R)CHC(Me)O)2Zn(Et)OEt}2] (R=OMe, 4; Me, 5; O tBu, 6), allowing a high oxygen content whilst remaining structurally suitable for use as precursors. The successful deposition of thin films of zinc oxide through aerosol-assisted chemical vapor deposition (AACVD), using a novel precursor, is described and fully characterized. [ABSTRACT FROM AUTHOR]

Single-source zinc β-iminoesterate precursors have been used for the first time in the aerosol-assisted chemical-vapour deposition (AACVD) of ZnO thin films. Depositions at 450 °C on silica-coated glass substrates produced strongly adherent films with excellent coverage of the substrate. The zinc β-iminoesterates [Zn(L1)2] ( 1) and [Zn(L2)2] ( 2) were synthesised by the reaction between ZnEt2 and 2 equiv. of a synthesised β-iminoester ligand CH3C[NHCH(CH3)2]CHC(O)OCH2CH3 (L1) and CH3C(NHCH3)CHC(O)OCH2CH3 (L2). The synthesised complexes were isolated and characterised by 1H and 13C 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. [ABSTRACT FROM AUTHOR]

Aerosol-assisted chemical vapour deposition (AACVD) reactions of GaMe3, ZnEt2 and the donor-functionalised alcohol HOCH2CH2OMe (6 equiv.) in toluene resulted in the deposition of amorphous transparent zinc gallate (ZnGa2O4) films at a range of temperatures (350-550 °C). The zinc-gallium oxide films were analyzed by scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray analysis, glancing-angle X-ray powder diffraction (XRD) and optical studies. The optimum growth temperature was found to be 450 °C, which produced transparent films with excellent coverage of the substrate. XPS confirmed the presence of zinc, gallium and oxygen in the films. Annealing these films at 1000 °C resulted in crystalline films and glancing-angle powder XRD showed that a zinc gallate spinel framework with a lattice parameter of a=8.336(5) Å was adopted. [ABSTRACT FROM AUTHOR]

Copper-based spinel oxide CuGa2O4 films have been deposited by means of a simple one-pot solution-based chemical vapour deposition (CVD) method. Aerosol-assisted (AA) CVD of copper(II) 2,2,6,6,-tetramethylheptan-3,5-dionate (thd), Cu(thd)2 and gallium(III) acetylacetonate, Ga(acac)3, in toluene resulted in the formation of transparent films with a slight yellow tinge at 300-500°C. Scanning electron microscopy (SEM) indicated that the films had grown by means of an island growth mechanism. Energy-dispersive X-ray (EDX) analysis and X-ray photoelectron spectroscopy (XPS) showed that CuGa2O4 had formed along with copper(I) oxide and gallium(III) oxide was observed at the surface of the film. Annealing the films under a range of conditions (air, N2, vacuum) resulted in oxidation and the formation of CuGa2O4 and copper(II) oxide, as shown by powder X-ray diffraction (XRD). The films were further analysed by UV/ Vis spectroscopy and atomic force microscopy. Similar AACVD depositions using copper(II) acetylacetonate, Cu(acac)2, and Ga(acac)3 in a range of solvents only resulted in the formation of gallium oxide owing to the lower solubility of the copper precursor than the gallium complex. AACVD is dependent on the precursor solubility hence Cu(thd)2 is a superior precursor to Cu(acac)2 owing to its increased solubility. [ABSTRACT FROM AUTHOR]

Highly transparent (>85 %) and conductive (1.086×10−3 Ω cm) zinc oxide thin films have been deposited from specifically selected precursors allowing us to establish a direct correlation between their molecular structure and the optoelectronic properties of the deposited films. Mono‐ligated ethyl zinc compounds of varying steric bulk: [EtZn(OC(Me)CH(Me)N(iPr))]2 (1), [EtZn(OC(OEt)CH(Me)N(iPr))]2 (2) and [EtZn(OC(OEt)CH(CH3)N(Dipp))]2 (3) were compared with the related bis‐ligated zinc complexes [Zn(OC(Me)CH(Me)N(iPr))2] (4), [Zn(OC(OEt)CH(Me)N(iPr))2] (5) and [Zn(OC(OEt)CH(Me)N(Dipp))2] (6). In all cases bulkier ligands resulted in poorer electronic properties of deposited films, whilst all mono‐ligated compounds were shown as superior precursors. All complexes were characterised by 1H and 13C{1H} NMR and elemental analysis, with the structure of 6 determined by single crystal X‐ray diffraction. Zinc oxide films were deposited from single and dual source (with methanol) reactions of these precursors, and analysed via XRD, XPS and EDX. Optoelectronic properties were investigated through UV/vis spectroscopy and Hall effect measurements, and morphology was examined via SEM. Tauc plots from UV/vis data indicated that Film A showed the lowest band gap of 3.31 eV. Varying the elemental composition of the precursors led to changes in the elemental composition of the resultant films, as well as changes in their structural and optoelectronic properties. Using this approach of precursor design, we have been able to tune single source precursors towards zinc oxide to deposit films with specific properties. [ABSTRACT FROM AUTHOR]

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 °C). Herein, we report the tuning of the decomposition profile (200–350 °C) of a range of octahedrally coordinated tris(β‐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 β‐ketoiminate ligands (R‐acnacH, R=Me, Et, iPr, 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. [ABSTRACT FROM AUTHOR]

Silver (Ag) amidinate metal organic decomposition precursors of the type: [Ag2((ArN)2C(H))2] (Ar = 2,6-dimethylphenyl (1), 2,6-diethylphenyl (2) and 2,6-diisopropylphenyl (3)) have been used for the first time in the deposition of Ag films on glass with multiple functionalities with potential application in optical/biological sensors or for use in electronic circuitry. Precursors 1–3 were isolated from the reaction of silver acetate with the appropriate ligand in a 1:2 stoichiometry and were characterized by 1H and 13C{1H} NMR, thermal gravimetric analysis and single crystal X-ray diffraction for 2. Single-layer depositions at 200 °C on glass substrates via spin coating produced transparent (>90% transmittance) coatings, with well-defined Ag nanoparticles. Multi-layer depositions at 200 °C on glass had a metallic lustre and were found to be conductive (ρ = 0.916–1.83 × 10−6 Ωm). All films were strongly adhered and displayed excellent coverage of the substrate. Ag films deposited from 1 to 3 were analysed by grazing incidence X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray analysis and scanning electron microscopy, with optical properties determined by UV-Vis spectroscopy. [ABSTRACT FROM AUTHOR]