Complexes of dialkylzinc compounds with tetrahydrofuran have been proposed as CVD sources for zinc oxide However, these complexes are not very stable, and they dissociate in the gas phase unless a more than 100-fold excess of tetrahydrofuran is used. [[i]].
[i] T. Kaufmann, G. Fuchs, M. Webert, Cryst. Research Tec., 1988, vol. 23, pp. 635-639
Dimethyl zinc-tetrahydrofuran adduct ZnMe2(thf), combined with oxygen as co-reactant, has been applied as precursor for the growth of nanostructured ZnO films as a compliant buffer layer for the growth of GaN films on Si (1 1 1) substrates. by liquid injection MOCVD. The use of the adduct complex with tetrahydrofuran avoids pre-reaction between the ZnMe2 complex and O2. The obtained ZnO films were stoichiometric and of high purity (no detectable carbon contamination). Nanowire-like morphology films were obtained at temperature higher than 350–550 °C. GaN layer growth by MBE on the obtained ZnO films resulted in the transformation of the ZnO nanowires to gallium oxide, with nearly complete removal of zinc from the films.[[i] ]
[i] Kate Black, Anthony C. Jonesa, Paul R. Chalker, Jeffrey M. Gaskella, Robert T. Murray, Tim B. Joyce, Simon A. Rushworth, Journal of Crystal Growth, Volume 310, Issue 5, 1 March 2008, Pages 1010–1014, Proceedings of the E-MRS Conference, Symposium G — Substrates of Wide Bandgap Materials . “MOCVD of ZnO thin films for potential use as compliant layers for GaN on Si”
Dimethylzinc adducts [Me2Zn(L)] (L = tetrahydropyran, furan or tetrahydrofuran,) have been applied as novel precursors for the growth of ZnO nanowires by liquid injection MOCVD over the temperature range 350–550 °C. The use of these ether adducts of dimethylzinc prevent premature pre-reaction with oxygen, and the grown at 500°C ZnO films present vertically-aligned nanowire morphology and intense near band-edge photoluminescence at emission energies of 3.26 to 3.28 eV and show minimal defect-related visible emission. The prepared ZnO nanowires have high purity, with carbon <0.5 at.-% by Auger electron spectroscopy. At other than 500°C deposition temperatures the grown ZnO films exhibited continuous polycrystalline morphologies. [[i] ]
[i] Kate Black, Paul R. Chalker, Anthony C. Jones, Peter J. King, John L. Roberts, Peter N. Heys, Chem. Vapor Deposition, Vol.16, Iss.1-3, p.106–111, 2010,“A New Method for the Growth of Zinc Oxide Nanowires by MOCVD using Oxygen-Donor Adducts of Dimethylzinc”
[Me2Zn(1,4-dioxane)] adduct, a potential MOCVD precursor for ZnO growth, was structurally characterized. As was determined by single crystal XRD , this adduct is polymeric with repeating [Me2Zn] units bridged by monodentate 1,4-dioxane ligands. The wide [Me-Zn-Me] bond angles (152.0(3)° suggest moderately weak [Me2Zn]-ligand interactions.
[ZnMe2(1,4-dioxane)] for ZnO nanowires CVD
Dimethylzinc dioxane adduct [ZnMe2(1,4-dioxane)] has been applied for the growth of vertically aligned ZnO nanowires by liquid injection MOCVD at temperatures 450-500 °C on Si(111) and F-doped SnO2/glass substrates. The prepared ZnO nanowires had wurtzitic phase., according to XRD. The nanowires had high crystalline quality, as found by room temperature PL measurement revealing intense near band-edge emission at 3.28 eV and a very low intensity of defect-related green luminescence at 2.42 eV. Dimethylzinc adduct chemistry revisited: MOCVD of vertically aligned ZnO nanowires using the dimethylzinc 1,4-dioxane adduct [[i]]
[i] R. Kanjolia A.C. Jones, S. Ashraf, J. Bacsa, K. Black, P.R. Chalker, P. Beahan, S. Hindley, R. Odedra, P.A. Williams, P.N. Heys Dimethylzinc adduct chemistry revisited: MOCVD of vertically aligned ZnO nanowires using the dimethylzinc 1,4-dioxane adduct
[ZnMe2(1,2-dimethoxyethane)] has been studied by single crystal XRD , it was found that it is a monomeric complex having a chelating 1,2-dimethoxyethane ligand, with wide [Me-Zn-Me] bond angle ( 154.5(2)°) suggesting moderately weak [Me2Zn]-ligand interactions.
In contrast, single-crystal X-ray structure of [ZnMe2(1,4-thioxane)] is polymeric, exhibiting nearly linear [Me-Zn-Me] bond angles, indicative of much weaker [Me2Zn]-ligand interactions.
The dimethylzinc bidentate ether adducts [ZnMe2(1,2-dimethoxyethane)] and [Zn Me2 (1,4-thioxane)] (as well as [ZnMe2(1,4-dioxane)]) have been applied as precursors for the growth of ZnO nanowires by liquid-injection MOCVD. The vertically aligned ZnO NWs (wurtzitic phase according to XRD) were obtained on Si(111) and F-doped SnO2/glass substrates in the absence of a seed catalyst. [ZnMe2(1,2-dimethoxyethane)] and [ZnMe2(1,4-dioxane)]) allowed to deposit ZnO nanowires at substrate temperatures of 450-500 °C, while [ZnMe2(1,4-thioxane)] required higher deposition temperature 550–600 °C for the nanowire growth. An intense near band-edge emission peak at 3.28 eV with a very low intensity of defect-related green luminescence at 2.42 eV was observed in the room-temperature PL spectra for the ZnO nanowires grown using [ZnMe2(1,2-dimethoxyethane)] and [ZnMe2(1,4-dioxane)]) precursors, proving high purity of ZnO, what was confirmed by the absence of detectable carbon by Auger electron spectroscopy measurements of ZnO films grown with these precursors. In contrast, [ZnMe2(1,4-thioxane)] produced ZnO nanowires with PL dominated by deep centre, defect-related emission at 2.42 eV, and AES spectra of ZnO films grown from [ZnMe2(1,4-thioxane)] detected significant sulfur contamination (1 at.-%).[[i] ]
[i] Sobia Ashraf, Anthony C. Jones, John Bacsa, Alexander Steiner, Paul R. Chalker, Peter Beahan, Sarah Hindley, Rajesh Odedra, Paul A. Williams, Peter N. Heys, “MOCVD of Vertically Aligned ZnO Nanowires Using Bidentate Ether Adducts of Dimethylzinc”