Tyndall National Institute - Doctoral Theses

Permanent URI for this collection


Recent Submissions

Now showing 1 - 5 of 211
  • Item
    A cross-disciplinary analysis of the materials used in the making of Irish works of art
    (University College Cork, 2023) Biolcati, Veronica; Iacopino, Daniela; Ó Macháin, Pádraig; Irish Research Council
    Nowadays, the fields of cultural heritage preservation and heritage science are experiencing a growing demand for non-invasive analytical methodologies. These approaches aim to minimize direct interaction with artefacts in order to minimize any potential damage. In fact, non-invasive analytical techniques, by virtue of their non-destructive nature, do not induce modifications in the physical or chemical constitution of the art objects, and they often obviate the need for sampling. Since decades, X-ray fluorescence spectroscopy (XRF) is routinely used as preliminary step in most analytical surveys of artworks. This publication-based thesis, under the auspices of the Inks & Skins project, presents three case studies which used XRF for the elemental characterization of the materials under analysis. XRF plaid a key role in all investigations, as it informed about material availability, artistic techniques, and manufacturing technologies among others. Following the introduction on the principle of XRF and a brief overview on inks and metals, chapter two presents the multi-analytical investigation of the Irish Gaelic manuscript on animal skin, the Book of Uí Mhaine. The presented publication was the culmination of an interdisciplinary analysis of the composing material and manufacturing techniques of the largest Gaelic Books surviving from the medieval vernacular period. XRF elucidated the elemental composition of inks, pigments, and parchment support. The extensive data collected in this study served as comparative tool for the undergoing research on the materials and techniques used in other (27 at the time of this thesis) medieval Irish manuscripts from different traditions. Chapter three presents the publication raising from the study of inks used to write nineteen satiric poems in Harward’s Almanac, a 17th century Dublin book. In this specific case XRF aided to establishing the original order in which the verses were written. Again, this work would have not been possible without a transdisciplinary approach which included paleography, codicology, material science, and statistical analysis. The fourth chapter offers a detailed description of an XRF-based analysis of three gold and silver medieval Irish chalices. This technical study was performed in order to put into historical contest a gilded silver chalice recently sold on auction as to be of medieval and Irish origin. This was done by comparing its materiality with two other late medieval silver-gilt chalices. The study helped to reveal their manufacturing technique, the nature of the decorating enamels and glass, and their story they went through. This work could have not been possible without the essential work and research of art historians. Finally, to highlight the enormous potential of XRF technique, all the analysis were performed on-site at partner institutions, libraries, and museums.
  • Item
    Two-dimensional transition metal dichalcogenides as next generation semiconductor materials
    (University College Cork, 2023) Coleman, Emma M.; Hurley, Paul; Cherkaoui, Karim; O'Dwyer, Colm; SFI Manufacturing; Horizon 2020 Framework Programme; European Research Council
    In recent years 2D materials, and more specifically transition metal dichalcogenisdes (TMD) MoS2 and WS2 have been investigated in the field of semiconductors as they exhibit energy gaps which span from semi-metals through to wide band gap semiconductors. Due to their thickness on an atomic scale, their properties differ from that of their bulk counterpart. The tunability of TMD bandgaps between the monolayers and bulk allows for a broader range of physical, electronic and optical properties and can be applied to a variety of applications including sensors, photode- tectors, flexible devices, optoelectronics, electronic (logic and memory) devices and green energy. This thesis focuses on the possible use of TMDs for the 3D back end of line (BEOL) integration of logic and memory and it investigates some of these challenges to help bridge the gap in the knowledge to strive for the reality of 3D BEOL. One of the approaches examined in this thesis is the mechanical exfoliation of TMD crystals. The interface properties of WS2 or MoS2 and insulating oxides is investigated with fabricated inverted MOSCAP (metal oxide semiconductor capacitor) structures, where a heavily doped silicon substrate is used as the back gate. With a variety of different devices, the impact of boundary defects is discussed along with a proposed bulk defect effects. Another important line of work is the improvement of TMD growth. Chemical vapour deposition (CVD) is a popular TMD growth process. Though high quality TMDs have been produced by CVD, there is a lack of knowledge about how to grow at lower temperature, in order to stay within the thermal budget of 3D BEOL. We investigate CVD grown MoS2 at temperatures lower than 550 °C and perform Hall data on transistors which provides positive mobility values and carrier concentrations. The significance of this work also shows findings in the nanoelectronic operation of atomic layer deposition (ALD) WS2. Insight is gained from Hall effect analysis and temperature dependent electronic studies, which are lacking in literature. Typically, for WS2 thin-films, the mobility values reported to date have been field effect mobility values extracted from transistor characteristics. More specifically, data includes the similarity of contact and sheet resistance temperature dependence in the WS2 device, indicating that both are dominated by the WS2 hole concentration temperature dependence. Moreover, rarely reported change in the TMD material, such as sheet resistance, due to device fabrication, is attributed to the chemicals and thermal treatments required to form the electronic devices. Finally, the aim of investigating laser annealed MoS2 was to show an in-depth investigation into synthetizing crystalline MoS2 layers on wafer scale area, where MoS2 films deposited on Si and Si/SiO2 surfaces are explored. This method shows that within the correct parameter range, the process can produce crystalline MoS2 films with small domains size of around 3.5 nm, from an initially amorphous MoS2 film. Field effect transistors formed in laser annealed MoS2 show limited Ids variation with Vgs consistent with the small domain size.
  • Item
    Multi–scale simulation of hybrid inorganic–organic films
    (University College Cork, 2023) Muriqi, Arbresha; Nolan, Michael; Horizon 2020
    The discovery of novel materials and associated process chemistries is crucial for the realization of higher performance electronic devices and the progress of nanotechnology in general. Hybrid materials are a special class of materials with unusual features which are attracting great interest for a wide range of applications. The unique properties of hybrid materials arise from the combination of advantages of both building blocks, i.e., inorganic and organic, which allow material functionalities that are not present in the individual components to be engineered. The properties of these materials can be also tuned depending on the requirements of the application by the choice of the components. Hybrid films are fabricated using molecular layer deposition (MLD) technique, a variant of the widely used atomic layer deposition (ALD) technique, which enables precision and control at the atomistic scale. In recent years, many MLD processes for hybrid films have been developed. However, much less is known about the growth mechanism of hybrid MLD films. In my thesis I used first principles density functional theory (DFT) simulations to investigate the key steps in the mechanism of hybrid film deposition through MLD, to address open questions around earlier MLD experiments and to predict the most suitable precursors for deposition processes. We build up an atomistic level understanding of the growth chemistry of different types of hybrid films by modelling the relevant MLD deposition processes. In particular, deep investigations on how precursor atomic structure determines film growth, stability and flexibility is carried out. We focus on the key MLD process chemistries, namely alucone and titanicone films, both of high interest for passivation layers in batteries. We assist the interpretation of experimental findings by showing for the first time why the ethylene glycol precursor performs poorly in making stable alucone films and why glycerol is better. For titaiocone films we highlight the role of the substrate and the titanium containing precursors on the initial MLD steps and in film production. We have also predicted that aromatic molecules are a good choice for stable hybrid films and their chemistry can be manipulated without impacting on the stability and this has been borne out by experimental work.Furthermore, we predict suitable MLD chemistries for production of hybrid antibacterial materials. We also study the diffusion phenomena of MLD precursors into polymeric substrates with the vapour phase infiltration (VPI) technique to understand the chemical interactions and corroborate the experimental data on Ru nanostructures and self-healing materials. Finally, we provide atomic level understanding around novel organometallic precursors and predict their applicability for deposition of oxide and hybrid thin films. The work in my thesis illustrates the key role of atomistic simulations in materials and process development.
  • Item
    Laser-induced graphene-like carbon for volatile organic compound sensing
    (University College Cork, 2023) Murray, Richard; Quinn, Aidan J.; Iacopino, Daniela; Science Foundation Ireland
    Laser-induced graphene-like carbon (LIG) is a potential resource-efficient fabrication route to support the abundance of sensors required by Industry 4.0 for IoT edge sensing applications, including wearables and worker safety LIG is formed \textit{in situ} by laser irradiation of suitable precursors, e.g. polyimide, to yield conductive, porous, 3D foams comprised of graphene sheetlets. This direct conversion allows for good spatial resolution (~ 50 um) and arbitrary pattern design, thus enabling the prototyping of diverse devices ranging from supercapacitors and interdigitated electrodes to electrochemical and Volatile Organic Compound (VOC) sensors. This thesis develops resource efficient, iterative system-agnostic optimisation procedures for LIG fabrication and novel back-contacting routes. Iterative use of design of experiments optimisation provides robust investigative route to determine ideal conditions with minimal investment of time and resources. An all-laser process of achieving back contacts from LIG to underlying metal was also demonstrated. Unlike current mechanical or silver paint contacts, back-contacts decouple the mechanical and electrical interface to external electronics, thus improving system reproducibility and, preventing surface contamination of the active material. Further, this scalable approach is a promising device integration route for both wafer-scale and printable electronics. Low-resource, low-power chemiresistive VOC sensors are also reported, comprised of low mass loadings of SnO nanoflowers (synthesised below 100oC and at ambient room pressure) on LIG electrodes. These offer a low-energy alternative to standard VOC sensors, which typically require high operational and fabrication temperatures (>300oC). These chemiresistive sensors can detect methanol vapor at laboratory temperature, with a limit of detection (170+/-40 ppm), below 8-hour exposure levels for worker safety (200 ppm). The sensors also demonstrated stable DC resistance responses \Delta R/R = 9+/-2% to 710 ppm of methanol for over 21 days in ambient conditions.
  • Item
    Performing women’s poetry: an evolving craft
    (University College Cork, 2023) Manning, Maria Hanora; Jenkins, Lee; Hanna, Adam; Irish Research Council
    This research project proposes to examine a current cohort of female poets employing performance techniques in their poetries, investigating how these poets continue to adapt and adopt the aesthetics of earlier poets. In recent years, the popularity of poetry in online communities has boomed, with an inevitable backlash to this poetic movement, criticising its contribution to poetry as a cultural form, such as Rebecca Watts’ PN Review article. Throughout this research, I aim to locate these poetries (often described as “digital” or “e- poetries”) along a continuum of performance, identifying the ways in which such a factor is evoked in both these new works and the work of earlier poets. Bearing in mind the theories John Miles Foley’s book Oral Literature and the Internet: Pathways of the Mind, which suggests the internet is a natural evolution of oral literature and spoken word poetries, I aim to connect the work of this cohort of poets with performance poets before them, examining the performative overlaps between oral and digital literatures. This project will interrogate the ways in which performance is enacted through a number of guises, from the sounds of orality and musicality, to the embodiment of performance by these poets. I aim to examine the creation of an aesthetic of performance among these women poets, paying particular attention to the ways the female body is performed in this work. Finally, I consider the social implications and contexts of such work, exploring the connections between poet and audience, the poetic persona and the performance of politics in these poetries. My research is primarily focused on work of poets disseminating their work chiefly through non-print methods, such as recording, performance, and social media, in the 21st Century. I will also examine the performance poetries of women poets in the 20th Century, examining the connections and creation ofa performance aesthetic, aiming to link the work of poets across these eras by examining a series of aspects of their poetics, such as the orality, the body, musicality, social engagement and public spheres of poetry.