http://hdl.handle.net/10468/41 The Tyndall National Institute is one of Europe's leading research centres, specialising in Information and Communications Technology (ICT) hardware. Wed, 22 May 2013 12:49:16 GMT 2013-05-22T12:49:16Z http://cora.ucc.ie:80/bitstream/id/77/Tyndall_logo20.jpg http://hdl.handle.net/10468/41 http://hdl.handle.net/10468/1056 Deposition of copper by plasma-enhanced atomic layer deposition using a novel N-Heterocyclic carbene precursor Coyle, Jason P.; Dey, Gangotri; Sirianni, Eric R.; Kemmell, Marianna L.; Yap, Glenn P. A.; Ritala, Mikko; Leskela, Markku; Elliott, Simon D.; Barry, Sean T. Two novel N-heterocyclic carbene (NHC)-containing copper(I) amides are reported as atomic layer deposition (ALD) precursors. 1,3-Diisopropyl-imidazolin-2-ylidene copper hexamethyldisilazide (1) and 4,5-dimethyl-1,3-diisopropyl-imidazol-2-ylidene copper hexamethyldisilazide (2) were synthesized and structurally characterized. The thermal behavior of both compounds was studied by thermogravimetric analysis (TGA), and they were both found to be reasonably volatile compounds. Compound 1 had no residual mass in the TGA and showed long-term stability at temperatures as high as 130 °C, while 2 had a residual mass of 7.4%. Copper metal with good resistivity was deposited using 1 by plasma-enhanced atomic layer deposition. The precursor demonstrated self-limiting behavior indicative of ALD, and gave a growth rate of 0.2 Å/cycle. Compound 2 was unsuccessful as an ALD precursor under similar conditions. Density functional theory calculations showed that both compounds adsorb dissociatively onto a growing copper film as long as there is some atomic roughness, via cleavage of the Cu-carbene bond. Fri, 01 Mar 2013 00:00:00 GMT http://hdl.handle.net/10468/1056 2013-03-01T00:00:00Z http://hdl.handle.net/10468/894 Hollow core photonic crystal fiber based viscometer with Raman spectroscopy Horan, Laura E.; Ruth, Albert A.; Garcia-Gunning, Fatima C. The velocity of a liquid flowing through the core of a hollow core photonic crystal fiber (driven by capillary forces) is used for the determination of a liquid's viscosity, using volumes of less than 10 nl. The simple optical technique used is based on the change in propagation characteristics of the fiber as it fills with the liquid of interest via capillary action, monitored by a laser source. Furthermore, the liquid filled hollow core photonic crystal fiber is then used as a vessel to collect Raman scattering from the sample to determine the molecular fingerprint of the liquid under study. This approach has a wide variety of indicative uses in cases where nano-liter samples are necessary. We use 10–12 cm lengths of hollow core photonic crystal fibers to determine the viscosity and Raman spectra of small volumes of two types of monosaccharides diluted in a phosphate buffer solution to demonstrate the principle. The observed Raman signal is strongest when only the core of the hollow core photonic crystal fiber is filled, and gradually decays as the rest of the fiber fills with the sample. Sat, 01 Dec 2012 00:00:00 GMT http://hdl.handle.net/10468/894 2012-12-01T00:00:00Z http://hdl.handle.net/10468/992 Nanostructured ferroelectric materials Varghese, Justin Manjaly Nanostructured materials are central to the evolution of future electronics and information technologies. Ferroelectrics have already been established as a dominant branch in the electronics sector because of their diverse application range such as ferroelectric memories, ferroelectric tunnel junctions, etc. The on-going dimensional downscaling of materials to allow packing of increased numbers of components onto integrated circuits provides the momentum for the evolution of nanostructured ferroelectric materials and devices. Nanoscaling of ferroelectric materials can result in a modification of their functionality, such as phase transition temperature or Curie temperature (TC), domain dynamics, dielectric constant, coercive field, spontaneous polarisation and piezoelectric response. Furthermore, nanoscaling can be used to form high density arrays of monodomain ferroelectric nanostructures, which is desirable for the miniaturisation of memory devices. This thesis details the use of various types of nanostructuring approaches to fabricate arrays of ferroelectric nanostructures, particularly non-oxide based systems. The introductory chapter reviews some exemplary research breakthroughs in the synthesis, characterisation and applications of nanoscale ferroelectric materials over the last decade, with priority given to novel synthetic strategies. Chapter 2 provides an overview of the experimental methods and characterisation tools used to produce and probe the properties of nanostructured antimony sulphide (Sb2S3), antimony sulpho iodide (SbSI) and lead titanate zirconate (PZT). In particular, Chapter 2 details the general principles of piezoresponse microscopy (PFM). Chapter 3 highlights the fabrication of arrays of Sb2S3 nanowires with variable diameters using newly developed solventless template-based approach. A detailed account of domain imaging and polarisation switching of these nanowire arrays is also provided. Chapter 4 details the preparation of vertically aligned arrays of SbSI nanorods and nanowires using a surface-roughness assisted vapour-phase deposition method. The qualitative and quantitative nanoscale ferroelectric properties of these nanostructures are also discussed. Chapter 5 highlights the fabrication of highly ordered arrays of PZT nanodots using block copolymer self-assembled templates and their ferroelectric characterisation using PFM. Chapter 6 summarises the conclusions drawn from the results reported in chapters 3, 4 and 5 and the future work. Sat, 01 Dec 2012 00:00:00 GMT http://hdl.handle.net/10468/992 2012-12-01T00:00:00Z http://hdl.handle.net/10468/922 Accommodating curvature in a highly ordered functionalized metal oxide nanofiber: synthesis, characterization and multi-scale modeling of layered nanosheets O'Dwyer, Colm; Gannon, G.; McNulty, D.; Buckley, D. Noel; Thompson, Damien A key element in the rational design of hybrid organic-inorganic nanostructures, is control of surfactant packing and adsorption onto the inorganic phase in crystal growth and assembly. In layered single crystal nanofibers and bilayered 2D nanosheets of vanadium oxide, we show how the chemisorption of preferred densities of surfactant molecules can direct formation of ordered, curved layers. The atom-scale features of the structures are described using molecular dynamics simulations that quantify surfactant packing effects and confirm the preference for a density of 5 dodecanethiol molecules per 8 vanadium attachment sites in the synthesised structures. This assembly maintains a remarkably well ordered interlayer spacing, even when curved. The assemblies of interdigitated organic bilayers on V2O5 are shown to be sufficiently flexible to tolerate curvature while maintaining a constant interlayer distance without rupture, delamination or cleavage. The accommodation of curvature and invariant structural integrity points to a beneficial role for oxide-directed organic film packing effects in layered architectures such as stacked nanofibers and hybrid 2D nanosheet systems. Mon, 01 Oct 2012 00:00:00 GMT http://hdl.handle.net/10468/922 2012-10-01T00:00:00Z