The synthesis of novel tungsten precursors for the CVD of tungsten oxide

The research described in this thesis has been concerned with the synthesis and characterisation of a range of tungsten(Vl) compounds for the CVD of tungsten oxide thin films. Three classes of compounds have been investigated; phenoxide compounds, donor-functionalised alkoxides and a fluorinated oxotetraalkoxide. Chapter One - Introduction - provides information on the applications of tungsten oxide thin films and a brief overview of the various deposition techniques available. Chemical vapour deposition (CVD) is then discussed with particular emphasis on atmospheric-pressure CVD (APCVD) and aerosol-assisted CVD (AACVD), followed by a review of precursors previously used for the deposition of tungsten oxide thin films. The chemistry of tungsten(VI) is then briefly discussed. Chapter Two - Tungsten(VI) Hexaphenoxides - details the synthesis, characterisation and subsequent AACVD of three tungsten(VI) hexaphenoxide compounds. The compounds have been characterised by NMR spectroscopy and single crystal X-ray diffraction before being used as AACVD precursors. Deposition conditions are described, followed by analysis of the films composition and optical properties. Chapter Three - Fluorinated Oxotetraalkoxide - describes the synthesis and characterisation of a monomeric fluorinated oxotetraalkoxide compound. The compound was characterised as monomeric by NMR and mass spectroscopy, and subsequently tested as an APCVD precursor. APCVD conditions are provided, followed by compositional and optical analysis of the thin films deposited. Chapter Four - Donor-functionalized Alkoxides - details the synthesis and characterisation of two tungsten(VI) donor- functionalized alkoxides and their subsequent use as AACVD precursors. Compounds have been characterised by variable temperature NMR spectroscopy before testing as AACVD precursors. Details of the AACVD conditions used, and the film analysis are included. There follows a brief conclusions section highlighting precursor properties and films deposited, in addition to suggestions for further work in this area. The appendices give crystallographic data, lCDD pattern number data and details of the instrumentation. Details of the CVD reactor and precursor delivery techniques used during this research are also included. (author)Available from British Library Document Supply Centre-DSC:DXN037067 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo