Abstract
Advancing the microelectronics industry requires the continuous exploration of emerging material fabrication methods, and compatible materials to meet evolving technological demands. This research focuses on the development of precursors to key semiconducting metal oxides that can be deposited using solution-based deposition techniques, in particular aerosol assisted chemical vapour deposition (AACVD) and aerosol jet printing (AJP). These methods offer a cost-effective, low-temperature approach for fabricating semiconducting thin films, allowing for scalable and versatile applications.Chapter 1: Introduction
This chapter presents a broad introduction to the research topic, covering essential discussions on band theory, semiconductor devices, metal oxides, and deposition techniques for thin film materials. An overview on the range of precursor systems that have been used to deposited metal oxide materials is presented, and discussion on precursor design included.
Chapter 2: Alkoxide Systems
Chapter 2 explores alkoxide systems in main group and transition metals, specifically focusing on precursors to Sn, Bi, and Ti oxides. A series of complexes containing a tridentate alkoxide ligand were synthesised and two taken forward for deposition trials. While the Sn and Ti complexes have been previously documented, this chapter extends efforts to broaden the family of complexes within this tris-alkoxide framework. Although attempts to synthesise novel complexes were met with limited success, the experimental procedures and findings are detailed comprehensively. Select complexes were successfully deposited via AACVD and spray deposition, with analysis conducted on the resultant films to evaluate their properties and structure.
Chapter 3: Group 14 Oxide Precursors
The second body of work describes the synthesis, characterisation and precursor
suitability assessment for a series of Sn(II)/(IV) and Ge(II)/(IV) aminoalkoxide
complexes. Several pro-ligands were devised based upon a successful ligand system reported in literature (dmamp). Proof of concept AACVD studies were carried out looking at the influence of solvent on the identity of the final materials. Spray coating depositions were also carried out resulting in GeOx materials from precursors in the +2 and +4 oxidation state.
Chapter 4: Heterobimetallic System
Having looked at precursors to binary Sn(II) oxides in chapters 2 and 3, chapter 4 investigated heterobimetallic systems containing Sn(II) and an alkali metal element (Li, Na or K), as a way of developing single source precursors to group 1 doped SnO. Through this work three catecholate complexes, incorporating Sn and either Li, Na or K, were synthesised and characterised using single crystal XRD, NMR experiments and TGA.
Chapter 5: Zinc Oxide
This chapter contains 4 key sections: Section 1 focuses on the development of single source precursors to ZnO materials. Through this a range of bi-dentate and tridentate aminoalkoxide ligands were synthesised and complexed to give a series of Zn(II) species. By altering the sterics of the systems via the substituents on the αC and central N group, the impact on the electronics of the systems and resulting precursor properties was explored. Section 2 takes a series of complexes established in section 1, three heteroleptic and one homoleptic system using the demamp ligand, and investigates the suitability of the systems as precursors to printed materials. Complexes are deposited using the spray coating deposition technique to determine suitability. Materials deposited are fully analysed using an array of materials characterisation techniques, and band gaps of the materials probed. Section 3 provides a short printing study using the Dimatix dmp inkjet printer in combination with the most successful system ZnO precursor system, deemed by section 2. Inks were formulated using the chosen system and printing parameters optimised for the ink. The final section of chapter 5 looks at incorporating dopants (Li) into spray coated films, to achieve p-type ZnO materials.
Chapter 6: Zinc-Tin-Oxide
The final results chapter looks at the co-deposition of complexes, described in chapters 3 and 5, as a means of fabricating Zinc Tin Oxide (ZTO). For comparison
two different deposition techniques, AACVD and spray deposition, using aerosols
as the transport mechanism are used to fabrication ZTO films. The synthesis and
characterisation of an additional ZnO precursor is detailed using a ligand system investigated in chapter 3. The thermal properties, solid and solution-state properties of the complex are reported.
| Date of Award | 25 Jun 2025 |
|---|---|
| Original language | English |
| Awarding Institution |
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| Supervisor | Andrew Johnson (Supervisor) & Matthew Jones (Supervisor) |
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