Synthesis, chemical vapour deposition and structural studies of group 13 alkoxides

• Main Author: Knapp, C. E.
• Published: University College London (University of London) 2010
• Subjects: 540
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.564962

This work is concerned with the synthesis of precursors to group 13 oxide thin films, and the subsequent chemical vapour deposition (CVD) of group 13 mixed metal oxide films. Investigations into the mechanisms at work during their decomposition via various techniques including gas phase electron diffraction (GED) is also discussed. A wide variety of group 13 alkoxides have been synthesised and characterised and described in this thesis. Significant findings support previous investigations showing the reaction of trialkyl group 13 complexes [MR3] with an excess of a donor functionalised alcohol does not yield a group 13 bis(alkoxide). However, compounds of the type [Ga(OR)nCl3-n] (n = 1, 2) have been synthesised using direct routes from gallium amido precursors, which are also described herein. In addition a wide variety of novel group 13 precursors incorporating a mixture of ligands leading to enhanced properties, desirable for CVD are presented. The gas phase structures of the dimethylalkoxygallanes, [Me2GaOCH2CH2NMe2]2 and [Me2GaOCH2CH2OMe]2 have been obtained via gas-phase electron diffraction from studying the vapour produced upon heating. Ab initio molecular orbital calculations are presented for these compounds, as well as the gas phase structure of [Me2GaOtBu]2. Only the monomeric forms [Me2GaOCH2CH2NMe2] and [Me2GaOCH2CH2OMe] are observed in the gas phase with donor functionalised ligands, whereas the dimer [Me2GaOtBu]2 remains intact in the gas phase. Gallium oxide films were grown via AACVD using a variety of group 13 precursors. The films deposited were not oxygen deficient and little carbon contamination was observed, which is attributed to being a direct result of precursor design. Thin films of indium gallium oxide, and zinc gallium oxide were also produced from the in situ reactions of InMe3, GaMe3 and HOCH2CH2OMe (for GaxIn2-xO3) and ZnEt2, GaMe3 and HOCH2CH2OMe (for GaxZnyO) via AACVD on silica substrates.