University of Bath PHD Development of Single-Source CVD Precursors for Group IV, V and VI Metal Disulfides Thompson, Joseph Award date: 2017 Awarding institution: University of Bath Link to publication Alternative formats If you require this document in an alternative format, please contact: [email protected] General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Download date: 11. Oct. 2021 Development of Single-Source CVD Precursors for Group IV, V and VI Metal Disulfides Joseph Robert Thompson A thesis submitted for the degree of Doctor of Philosophy University of Bath Department of Chemistry October 2016 COPYRIGHT Attention is drawn to the fact that copyright of this thesis/portfolio rests with the author and copyright of any previously published materials included may rest with third parties. A copy of this thesis/portfolio has been supplied on condition that anyone who consults it understands that they must not copy it or use material from it except as permitted by law or with the consent of the author or other copyright owners, as applicable. Contents Acknowledgements ...................................................................................................... 7 Declaration ................................................................................................................... 7 Abstract ........................................................................................................................ 8 List of complexes ......................................................................................................... 9 Abbreviations ............................................................................................................. 11 Chapter 1: Introduction .............................................................................................. 13 1.1 Two dimensional materials .............................................................................. 14 1.2 Transition metal dichalcogenides ..................................................................... 16 1.2.1 Structure .................................................................................................... 16 1.2.2 Electronic properties ................................................................................. 19 1.2.3 Mechanical properties ............................................................................... 21 1.2.4 Applications of bulk TMDs ...................................................................... 22 1.2.5 Applications of monolayers ...................................................................... 23 1.2.6 Synthesis of TMD thin films ..................................................................... 25 1.3 Chemical Vapour Deposition ........................................................................... 29 1.3.1 Overview ................................................................................................... 29 1.3.2 Variations of CVD .................................................................................... 31 1.3.3 AACVD .................................................................................................... 34 1.3.4 LPCVD ...................................................................................................... 36 1.4 CVD precursors ................................................................................................ 37 1.4.1 Multi-source precursors ............................................................................ 37 1.4.2 Single-source precursors ........................................................................... 37 1.4.3 Precursor design ........................................................................................ 38 1.5 Metal chalcogenide single-source precursors .................................................. 40 1.5.1 Chalcogenolates ........................................................................................ 40 1.5.2 Dichalcogenocarbamates........................................................................... 42 1 1.5.3 Monothiocarboxylates ............................................................................... 44 1.5.4 Xanthates ................................................................................................... 45 1.5.5 Dichalcogenphosphinates .......................................................................... 47 1.5.6 Phosphinochalcogenoic amidates ............................................................. 48 1.5.7 Dichalcogenoimidodiphosphinates ........................................................... 50 1.5.8 Thio-/dithio-biurets ................................................................................... 51 1.5.9 Thiourea adducts and thioureides.............................................................. 52 1.6 Insertion reactions ............................................................................................ 53 1.7 Aims and objectives ......................................................................................... 55 1.8 References ........................................................................................................ 55 Chapter 2: Ti, Zr and Hf sulfide precursors ............................................................... 63 2.1 Introduction ...................................................................................................... 64 2.1.1 Group IV disulfides ................................................................................... 64 2.1.2 TiS2 precursors .......................................................................................... 64 2.1.3 ZrS2 precursors .......................................................................................... 67 2.1.4 HfS2 precursors ......................................................................................... 68 2.1.5 Group IV selenide and telluride precursors .............................................. 68 2.2 Group IV thioureides........................................................................................ 69 2.2.1 Existing group IV thioureide systems ....................................................... 69 2.2.2 Synthesis and characterisation of titanium thioureide systems ................. 71 2.2.3 Synthesis and characterisation of zirconium and hafnium thioureide systems ............................................................................................................... 80 2.2.4 Thermogravimetric analysis ...................................................................... 88 2.2.5 AACVD of group IV thioureides .............................................................. 92 2.3 Group IV Dithiocarbamates ............................................................................. 94 2.3.1 Existing group IV dithiocarbamate systems ............................................. 94 2.3.2 Synthesis and characterisation .................................................................. 95 2 2.3.3 Thermogravimetric analysis .................................................................... 103 2.3.4 AACVD of [Zr(S2CNEt2)4] (12) ............................................................. 107 2.3.5 LPCVD of [Ti(S2CNEt2)4] (11) .............................................................. 109 2.3.6 LPCVD of [Zr(S2CNEt2)4] (12) .............................................................. 113 2.3.7 LPCVD of [Hf(S2CNEt2)4] (13) .............................................................. 118 2.4 Conclusion ..................................................................................................... 122 2.5 References ...................................................................................................... 125 Chapter 3: Ta sulfide precursors .............................................................................. 128 3.1 Introduction .................................................................................................... 129 3.1.1 Tantalum disulfide .................................................................................. 129 3.1.2 TaS2 precursors ....................................................................................... 130 3.2 Tantalum thioureides ...................................................................................... 130 3.2.1 Synthesis and characterisation of PDMAT based complexes ................. 130 t 3.2.2 Synthesis and characterisation of [( BuN)Ta(NMe2)3] (20) based complexes ......................................................................................................... 134 3.2.3 Thermogravimetric analysis .................................................................... 139 3.3 Tantalum dithiocarbamates ............................................................................ 142 3.3.1 Synthesis