End Point Detection in Reactive Ion Etching

End-point detection for deep reactive ion etch of silicon in the semiconductor industry has been investigated with a focus on statistical treatments on optical emission spectroscopy. The data reduction technique Principal components analysis (PCA) has been briefly reviewed and analysed as an introduction to independent component analysis (ICA). ICA is a computational dimension reduction technique capable of separating multivariate data into single components. In this instance PCA and ICA are used in to combine the spectral channels of optical emission spectroscopy of plasma processes into a reduced number of components. ICA is based on a fixed-point iteration process maximizing non-gaussianity as a measure of statistical independence. ICA has been shown to offer an improvement in signal to noise ratio when compared to principal component analysis, which has been widely used in previous studies into end-pointing. In addition to the end-point investigation, a study was carried out into the fabrication of arrays of free standing silicon nanorods. The fabrication process consisted of an electron beam lithograpy stage to pattern bare silicon, followed by a deep reactive ion etch - using the Bosch process - to create the nanorods. A variety of difference diameter nanorods, with a selection of pitch dimensions were created using this technique

Crystal Engineering and Structural Solutions of Organic Molecular Materials

Organic molecular materials have been studied for decades, with a strong focus on their application within gas uptake and selective separations. Porous organic molecules can come in multiple forms, whether a discrete molecule such as a macrocycle or cage, or an infinite framework, such as a hydrogen bonded organic framework (HOF). In this thesis, we will examine the benefits of crystal engineering as an alternative route towards the formation of new organic molecular structures. The molecular structures discussed in this thesis include organic molecular cages, hydrogen bonded organic frameworks and organic co-crystals. Crystal engineering has been posed as an impressive method for the discovery of new materials, without the time costly effort of finding alternative precursors, or finding the best possible reaction conditions. There are multiple routes towards recrystallisation, which are suitable whether soluble or insoluble, which can be utilised to direct alternative crystal packing, hence, alternative functionality. The dynamic nature of organic molecular cages, which are synthesised via reversible imine condensation reactions, is discussed in detail in chapter 2. TCC1[3+6], a trigonal prismatic cage underwent re-equilibration in solution to the truncated tetrahedron cage, stoichiometrically twice the equivalent, TCC1[6+12]. The cage formation was optimised synthetically, and furthermore experimental observations were rationalised through computational analyses. A series of organic molecular cages were synthesised via high throughput techniques using robotics, which were then fully characterised and their crystal structures determined. From this, a series of discoveries were made, including further illustration of re-equilibration in C21, from a [3+2] cage to a [6+4]. The formation of a new topology for C18 was also discovered, a bridged catenane with a novel topology not previously seen in literature. High throughput methods were also used in Chapter 4. However as opposed to the modelling the potential structure in silico, as in Chapter 3, the cages were chosen based on precursors capable of hydrogen bonding or organic salt formation. We showed it is possible to synthesised porous co-crystals from small organics, and furthermore discuss the benefits of using a bespoke high throughput infra-red kit, capable of determining the isosteric heat of adsorption. Porous structures by strategic design are also discussed in chapter 4, focusing on an alternative method using both crystal structure prediction (CSP) and energy-structure-function maps (ESFs) to increase the rate of porous material discovery. T1 and T2 are both triptycene-based hydrogen bonding tectons, which are capable of forming hydrogen-bonded organic frameworks. The ESFs enabled rationalisation of the experimental findings, and furthermore provided insight into the importance of hydrogen bond donors and acceptors through comparison of T1 and T2

Photocatalytic Oxygen Evolution from Cobalt-Modified Nanocrystalline BiFeO3 Films Grown via Low-Pressure Chemical Vapor Deposition from beta-Diketonate Precursors

BiFeO3 is an interesting multifunctional narrow band gap semiconductor that exhibits simultaneous multiferroic, photovoltaic, and photocatalytic behavior. Hence there is much interest in the growth of thin films of BiFeO3 via chemical vapor deposition (CVD); however, the number of suitable bismuth precursors is severely limited. A series of homoleptic bismuth(III) β-diketonate complexes were synthesized via simple room temperature ligand-exchange reactions from [Bi(N(SiMe3)2)3] and free diketonate ligands, which yielded the crystal structure of [Bi(acac)3] as a 1-D polymer. We attempted to use these complexes for low pressure CVD (LPCVD) growth of BiFeO3 films with [Fe(acac)3]; however, all bismuth complexes exhibited poor volatilities and decomposition characteristics, and as a result film growth was unsuccessful. Subsequently, the volatile alkoxide [Bi(OtBu)3], with [Fe(acac)3], was used to grow dense BiFeO3 films via low pressure CVD. The BiFeO3 films possessed multiferroic properties at room temperature and exhibited activity for visible light-driven water oxidation in the presence of a Ag+ electron scavenger, which improved significantly when modified with a cobalt surface cocatalyst. The increase in activity, probed by time-resolved photoluminescence spectroscopy, was attributed to improved charge carrier separation arising from the in-built internal electric field of BiFeO3 in addition to the presence of an efficient cobalt oxygen evolution catalyst

Study protocol to investigate the effects of testosterone therapy as an adjunct to exercise rehabilitation in hypogonadal males with chronic heart failure

BACKGROUND: Testosterone deficiency is a common occurrence in men with chronic heart failure (CHF) and may underpin features of advanced disease, including reduced skeletal muscle mass and fatigue. It is positively correlated with cardiac output and exercise capacity in patients with CHF, whereas a significant improvement in both these parameters has been observed following testosterone replacement therapy. Testosterone therapy has also been shown to reduce circulating levels of inflammatory markers, (TNF-α, sICAM-1 and sVCAM-1) in patients with established coronary artery disease and testosterone deficiency. This pilot study will assess the feasibility of a combined exercise rehabilitation and adjunctive testosterone therapy intervention for evoking improvements in exercise capacity, circulating inflammatory markers, cardiac and skeletal muscle function, indices of psychological health status and quality of life in hypogonadal males with chronic heart failure. METHODS/DESIGN: Following ethical approval, 36 patients will be randomly allocated to one of two groups: testosterone or placebo therapy during exercise rehabilitation. A combined programme of moderate intensity aerobic exercise and resistance (strength) training will be used. The primary outcome measure is exercise capacity, assessed using an incremental shuttle walk test. Secondary outcome measures include measures of peak oxygen uptake, cardiac function, lower-limb skeletal muscle contractile function and oxygenation during exercise, circulating inflammatory markers, psychological health status and quality of life. DISCUSSION: Exercise rehabilitation can safely increase exercise capacity in stable CHF patients but there is a need for studies which are aimed at evaluating the long-term effects of physical training on functional status, morbidity and mortality. This pilot study will provide valuable preliminary data on the efficacy of testosterone therapy as an adjunct to exercise rehabilitation on a range of functional, physiological and health-related outcomes in this patient population. Preliminary data will be used in the design of a large-scale randomised controlled trial, aimed at informing clinical practice with respect to optimisation of exercise rehabilitation in this patient group

Synthesis and Characterisation of Various Diester and Triester Adducts of TiCl4

Titanium(IV) chloride and the triester glycerol tribenzoate (gtb) were reacted under moisture-free conditions in order to investigate the use of triester-containing oils in the purification of TiCl4 in industrial processes. This resulted in the isolation of a chloro-bridged dimeric complex containing four titanium centres [{(TiCl4)2(gtb)}2] (1). Further novel coordination compounds of TiCl4 and the diesters; diisopropyl malonate, dibenzyl malonate and diethyl succinate were synthesised by direct reaction under moisture-free conditions, yielding [TiCl4{CH2(COOiPr)2}] (2), [TiCl4{CH2(COOCH2Ph)2}] (3) and [TiCl4{C2H4(COOEt)2}] (4) respectively. The structures of compounds 1–4 were determined by single-crystal X-ray diffraction. All structures assumed an octahedral geometry consisting of the titanium bound to four chloride ligands and the diester molecule acting as a bidentate ligand, through its two carbonyl oxygen atoms. Exposure of the isopropyl malonate reaction to trace amounts of water during synthesis resulted in the formation of an oxo-bridged dimeric structure [Ti2(μ-O)Cl3{CH2(COOiPr)2}2] (2b), the structure of which was also obtained via single-crystal X-ray diffraction

A single-source precursor approach to solution processed indium arsenide thin films

This paper reports the synthesis of the novel single-source precursor, [{(MeInAstBu)3}2(Me2InAs(tBu)H)2] and the subsequent first report of aerosol-assisted chemical vapour deposition of InAs thin films. Owing to the use of the single-source precursor, highly crystalline and stoichiometric films were grown at a relatively low deposition temperature of 450 °C. Core level XPS depth profiling studies showed some partial oxidation of the film surface, however this was self-limiting and disappeared on etch profiles. Valence band XPS analysis matched well with the simulated density of state spectrum. Hall effect measurements performed on the films showed that the films were n-type with promising resistivity (3.6 × 10−3 Ω cm) and carrier mobility (410 cm2 V−1 s−1) values despite growth on amorphous glass substrates

Cage doubling: solvent-mediated re-equilibration of a [3+6] prismatic organic cage to a large [6+12] truncated tetrahedron

We show that a [3 + 6] trigonal prismatic imine (a) cage can rearrange stoichiometrically and structurally to form a [6 + 12] trigonal prismatic imine (a) cage can rearrange stoichiometrically and structurally to form a [6 + 12 cage (b) with a truncated tetrahedral shape. Molecular simulations rationalize why this rearrangement was only observed for the prismatic [3 + 6] cage TCC1 but not for the analogous [3 + 6] cages, TCC2 and TCC3. Solvent was found to be a dominant factor in driving this rearrangement

The simplest supramolecular helix

Diethylamine is the smallest and simplest molecule that features a supramolecular helix as its lowest energy aggregate.</p

The role of glacier mice in the invertebrate colonisation of glacial surfaces: the moss balls of the Falljökull, Iceland

Glacier surfaces have a surprisingly complex ecology. Cryoconite holes contain diverse invertebrate communities while other invertebrates, such as Collembola often graze on algae and windblown dead organic on the glacier surface. Glacier mice (ovoid unattached moss balls) occur on some glaciers worldwide. Studies of these glacier mice have concentrated on their occurrence and mode of formation. There are no reports of the invertebrate communities. But, such glacier mice may provide a suitable favourable habitat and refuge for a variety of invertebrate groups to colonise the glacier surface. Here we describe the invertebrate fauna of the glacier mice (moss balls) of the Falljökull, Iceland. The glacier mice were composed of Racomitrium sp. and varied in size from 8.0 to 10.0 cm in length. All glacier mice studied contained invertebrates. Two species of Collembola were present. Pseudisotoma sensibilis (Tullberg, 1876) was numerically dominant with between 12 and 73 individuals per glacier mouse while Desoria olivacea (Tullberg, 1871) occurred but in far lower numbers. Tardigrada and Nematoda had mean densities of approximately 200 and 1,000 respectively. No Acari, Arachnida or Enchytraeidae were observed which may be related to the difficulty these groups have in colonizing the glacier mice. We suggest that glacier mice provide an unusual environmentally ameliorated microhabitat for an invertebrate community dwelling on a glacial surface. The glacier mice thereby enable an invertebrate fauna to colonise an otherwise largely inhospitable location with implications for carbon flow in the system