One of the poly-Si thin-film cells developed at the University of New South Wales (UNSW) is the EVA cell. In this work, SiN films for EVA cells as an antireflection/barrier coating were investigated. In addition, the effect of hydrogenation pre-treatment of solid phase crystallisation (SPC) on grain size and open-circuit voltage (Voc) was investigated. The SiN films deposited by PECVD were examined for uniformity of the thickness and the refractive index of the films across the position of the samples in the PECVD deposition system. A spectrophotometric analysis was used to determine these film properties. It was found that these properties were very uniform over the deposition area. Good repeatability of the depositions was also observed. A series of SiN film depositions by reactive sputtering were also performed to optimize the deposition process. Parameters adjusted during the deposition were nitrogen flow rate, substrate bias, and substrate temperature. By investigating the deposition rate, refractive index, and surface roughness of the films, the three deposition parameters were optimised. The effects of post SiN deposition treatments (a-Si deposition, SPC, RTA, and hydrogenation) on thickness and refractive index of both SiN films deposited by PECVD and reactive sputtering were investigated by using samples which have the same structure as the EVA cells. The thickness of the PECVD SiN films decreased about 6 % after all the treatments. On the other hand, the thickness reductions of the reactively sputtered SiN films were very small. The refractive index of the PECVD SiN films increased about 0.6 % after the treatments, whereas that of the reactively sputtered SiN films decreased 1.3 % after the treatments. As a possible method to improve the performance of EVA cells, hydrogenation of a-Si was investigated as a pre-treatment of SPC process. There were no obvious differences in the grainsize and the Voc of the EVA cells with and without the hydrogenation. Therefore it is likely that the hydrogenation pre-treatment of SPC does not have a beneficial effect on the performance of EVA cells.

Thin-film solar cells on glass substrates are likely to have a bright future due to the potentially low costs and the short energy payback times. Polycrystalline silicon (poly-Si, grain size &gt 1 pm) has the advantage of being non-toxic, abundant, and long-term stable. Glass as a substrate, however, limits the processing temperatures to ~600??C for longer process steps. Films with large grain size can be achieved by solid phase crystallisation (SPC), and especially by solid phase epitaxy (SPE) on seed layers, using amorphous silicon deposited at low temperatures as a precursor film. With SPC and SPE, the amorphous silicon film is typically crystallised at ~600??C over hours. During this anneal at atmospheric pressure -depending on the properties of the amorphous silicon film- ambient gas can percolate the film and can negatively affect the crystallisation. In this work, a high-vacuum anneal chamber was designed and built to allow the in-situ crystallisation of amorphous silicon films deposited on glass in a PECVD cluster tool. An important aspect of the design was the comfortable and safe operation of the vacuum anneal chamber to enable unattended operation. This was realised by means of a state-of-the-art, programmable temperature controller and a control circuit design that incorporates various safety interlocks. The chamber interior was optimised such that a temperature uniformity of 2-3K across the sample area was achieved. The chamber was calibrated and tested, and SPC and SPE samples were successfully crystallised. In initial SPC crystallisation experiments with solar cell structures, after post-deposition treatments, a 1 -sun open-circuit voltage of 465 mV was obtained, similar to furnace-annealed samples. In initial experiments with SPE solar cell structures, difficulties regarding the characterisation of the unmetallised solar cells with the quasi-steady-state open-circuit voltage method (QSSVOC) were encountered after post-deposition hydrogen treatment. A possible explanation for these difficulties is the contact formation with the metal probes. Furthermore, limiting factors of the QSSVOC method for the characterisation of unmetallised cells with high contact resistance values were investigated and, additionally, the accuracyof the QSSVOC setup was improved in the low light intensity range.

A major challenge affecting the likelihood of a new drug reaching the market is poor oral bioavailability derived from low aqueous solubility. Nanocrystals are rapidly becoming a platform technology to address poor solubility issues, although several challenges including stabilisation and control of particle size distribution for nanosuspensions still need to be addressed. The aim of this study was to revisit the simplest approach of re-precipitation and to identify the critical parameters, including the effect of different stabilisers as well as process conditions. We utilised a combined approach of both experiments and molecular modelling and simulation, not only to determine the optimum parameters but also to gain mechanistic insight. The experimental studies utilised three rather distinct, relatively insoluble drugs, the hypoglycaemic glibenclamide, the anti-inflammatory ibuprofen, and the anti-malarial artemisinin. The choice of crystal growth inhibitors/stabilizers was found to be critical and specific for each drug. The effect of the process variables, temperature, stirring rate, and the solute solution infusion rate into the anti-solvent, was rationalized in terms of how these factors influence the local supersaturation attained at the earliest stages of precipitation. Coarse grained simulation of antisolvent crystallisation confirmed the accepted two step mechanism of nucleation at high supersaturation which involves aggregation of solute particles followed by nucleation. Recovery of nanocrystals from nanosuspensions is also a technical challenge. A novel approach involving the use of carrier particles to recovery the nanocrystals was developed and shown to be able to recover more than 90% of the drug nanocrystals. The phase stability of nanocrystals along with bulk crystals for the model compound glycine was explored using molecular dynamics simulation. The simulations were consistent with experimental data, a highlight being the β phase transforming to the δ phase at temperature >400K and 20kbar respectively, as expected. Nanocrystals of α, β and γ glycine, however did not show any phase transformation at high temperature. In summary the study demonstrates that standard crystallization technology is effective in producing nanocrystals with the primary challenge being physico-chemical (rather than mechanical), involving the identification of molecule-specific crystal growth inhibitors and/or stabilizers. The developed nanocrystal recovery method should enable the production of nanocrystals-based solid dosage forms. The molecular simulation studies reveal that crystal-crystal phase transformations can be predicted for hydrogen-bonded systems.

New materials can be fabricated using small scaled building blocks as a repetition unit. Nanoparticles with their unique size-tuneable properties from quantum confinement can especially be utilised to form two- and three-dimensional ordered assemblies to introduce them into what would normally be considered to be incompatible matrices. Furthermore, new collective properties that derive from the ordered arrangement of the building blocks, are accomplished. Additionally, different materials can be combined by mixing different building blocks during self-assembly, so that size ranges and material combinations that are difficult to achieve by other means can be formed. The arrangement of small particles into highly ordered arrangements can be realised via self-assembly. To achieve such assemblies, highly monodisperse nanoparticular building blocks with a size distribution below 5 % have to be synthesised. The production and variation in the size of both lead chalcogenide and noble metal nanoparticles is presented in this work. Moreover, the syntheses of multicomponential nanoparticles (PbSe/PbS and Au/PbS) are investigated. Non-classical crystallisation methodologies with their varyious self-assembly mechanisms are used for the formation of highly symmetrical mesocrystals and supracrystals. Analogous to classical crystallisation methods and their formation processes the interparticle interactions, attractive as well as repulsive, determine the resulting crystalline structure. Variation of the environmental parameters consequently leads to structural variation due to the changing interparticle interactions. In contrast to classical crystallisation the length scale of the interparticle forces stays constant as the size dimension of the self-assembled building unit is changed. Two different non-classical crystallisation pathways are investigated in this work. One pathway focuses on the slow destabilisation of nanoparticles in organic media by the addition of a non-solvent. In this approach optimisation of parameters for the formation of highly symmetrical three-dimensional mesostructures are studied. Furthermore, to shine some light onto the mechanism of self-assembly, the intrinsic arrangement of the building units in a mesocrystal and the steps of non-solvent addition are analysed. The mechanistic investigations explain the differences observed in mesocrystal formation between metal and semiconductor nanoparticles. The lower homogeneity of the building units of the metal nanoparticles leads to smaller and less defined superstructures in comparison to semiconductor building blocks. Another pathway of non-classical crystallisation is the usage of electrostatic interactions as the driving force for self-assembly and supracrystal formation. Therefore, the building blocks are transferred into aqueous media and stabilised with oppositely charged ligands. The well-know procedure for metal nanoparticles was adapted for semiconductor materials. The lower stability of these nanoparticles in aqueous solution induces an agglomeration of the semiconductor nanoparticles without including oppositely charged metal nanoparticles. The destabilisation effect can be increased by the addition of equally charged metal nanoparticles in a salting out type process. In comparison to the slow formation of mesocrystals achieved via destabilisation in an organic media (up to 4 weeks), the salting out procedure takes place within two hours, but the faster agglomeration causes a less well defined assembly of the building units in the mesocrystals. Moreover, the arrangement of semiconductor nanoparticles with organic molecules such as polymers and proteins was investigated in order to use the nanoparticles as a light harvesting component. In combination with the directly bound polymer the charge carrier may be directly transferred to the conductive thiophene-based polymer, so that infrared light can be transformed into an electrical signal for use in further applications such as solar cells. The advantage of the nanoparticle-protein system is the self-assembly across a liquid-liquid interface and additionally a Förster resonance energy transfer can occur at this phase boundary. Hence, it is possible to transfer highly energetic photons directly to biological samples without destroying the biological material.

Mt Kilimanjaro, Africa's highest mountain (5895m), is a large, young (<1.6Ma) stratovolcano at the southern end of the East African Rift, in northern Tanzania. Consisting of three distinct volcanic centres, Shira, Mawenzi and Kibo, Shira contains the highest proportion of mafic rocks. Shira samples are strongly silica under-saturated rocks, ranging from picro-basalt, to nephelinite and hawaiite (Mg numbers (Mg #) ranging from 77.2-35.5). Phenocrysts constitute up to 55% of some samples, and include aluminous augite (often containing abundant fluid and/or melt inclusions), olivine (Fo92-Fo49), plagioclase (An75-An42), nepheline (Ne77-Ne68), magnesiochromite and ulvöspinel. Groups identified on the basis of phenocryst assemblages and textures correlate with location. East Shira Hill samples contain olivine and clinopyroxene phenocrysts + microphenocrysts of plagioclase (Group 1), or plagioclase and clinopyroxene phenocrysts + microphenocrysts of olivine (Group 2). Samples with high Mg #'s contain abundant cumulate clinopyroxene and olivine (Fo92-Fo85). Group 3 samples (Shira Ridge) contain nepheline phenocrysts and Group 4 samples (Platzkegel) have distinct intergranular textures. Chondrite normalised REE patterns are steep, with light REE-enrichment up to 400x chondrite. Spider diagrams, normalised to OIB for primitive Shira samples have strong K depletions and Pb enrichments. The source of the Shira volcanic rocks is most likely an amphibole-bearing spinel lherzolite, in which amphibole remains residual. Similarities in spider diagram patterns and trace element ratios suggest a source similar to average OIB. The Shira volcanic centre is a polygenetic volcano, in which multiple small volume, low degree (4-10%) partial melts from a metasomatised subcontinental lithospheric mantle follow pre-existing structural weaknesses, before ponding in the lithosphere. Evolution of these small volume melts is dominated by shallow fractional crystallisation of clinopyroxene, olivine±spinel, with plagioclase also fractionating from Group 4 (Platzkegel) samples. A magma mixing origin is suggested for some samples and supported by complex zonation patterns in major and trace element chemistry of clinopyroxene phenocrysts as well as linear mixing arrays. The Shira volcanic centre has since ceased activity, and collapsed to form the present day Shira Ridge and caldera before being overlain by various Kibo and parasitic lavas to the east and northwest of the Shira region.

An improved crystallisation spectrometer has been designed, built and tested. It is to be used by others to gain new knowledge about the solidification of matter by study of the crystallisation of hard sphere colloid samples that are an established model for the behaviour of some aspects of atoms. In this crystallisation spectrometer, expanded and collimated green laser light is Bragg scattered from the colloidal crystals as they form, and the diffracted light is focused by a liquid filled hollow glass hemispherical lens onto low cost CCD array detectors that are rotated about the optical axis to average the intensities around the whole Debye-Scherrer cone of scattered light. The temperature of the sample is controlled to +/-0.1„a, and because of the ability to change the refractive index of the sample particles with temperature, this is utilised to control the amount of scattering from the sample Also, this spectrometer uniquely exploits the refractive index match of the colloidal particles, the solvent, the bath liquid, and the glass used for both the sample bottle and the hollow glass hemisphere. A unique facility has been incorporated to permit tumbling of the sample prior to the measurement commencing to shear-melt any pre-existing crystals. This ensures that the sample is completely fluid and is at the correct temperature at the start of the measurement. The instrument is assembled on an optical table and is computer controlled. Results presented show that this new spectrometer with its use of the whole Debye-Scherrer cone of Bragg scattered light and other enhancements gives insight into the crystallisation process more than one order of magnitude of time earlier than previous light scattering experiments, providing new knowledge about the crystallisation process.

Thin film silicon on low temperature glass substrates is currently seen as the best path toreduce the $/W cost of photovoltaic (PV) modules. However, producing thin film polysilicon, on glass, is an ongoing research challenge. Laser crystallisation of a-Si is one of the possible methods. Typically excimer (XMR) lasers are used for laser crystallisation. This thesis introduces the copper vapour laser (CVL) as a viable alternative for thin film photovoltaic applications. The CVL, like the XMR, is a high powered, pulsed laser. However, the CVL has higher pulse rates (4-20kHz), better beam quality and a visible wavelength output (578 & 511nm). Preliminary experiments, using 600K-heated silicon-on-quartz samples, confirmed that CVL crystallisation can produce area weighted average grain size of 0.1-0.15??m, which is comparable to results reported for XMR??? s. Importantly, the CVL results used thicker films (1??m), which is more applicable to thin photovoltaic devices that need 1-10??m of silicon to be viable. The CVL??? s longer wavelength and therefore longer penetration depth (1/alpha) are proffered as the main reason for this result. Extensive laser-thermal modelling highlighted further opportunities specific to CVL crystallisation. Through-the-glass doublesided irradiation was shown in simulations to reduce thermal gradients, which would enhance crystal growth. The simulations also produced deeper melts at lower surface temperatures, reducing the thermal stress on the sample. Subsequent experiments, using silicon-on-glass, confirmed the benefit of through-the-glass doublesided irradiation by maintaining grain sizes without the usual need for substrate heating. Furthermore, Raman analysis showed that doublesided crystallisation achieved full depth crystallisation, unlike single side irradiation which produced partial crystallisation. A new mode of crystallisation, stepwise crystallisation, was also postulated whereby a series of CVL pulses could be used to incrementally increase the crystallisation depth into the silicon. Simulations confirmed the theoretical basis of the concept, with HeNe Raman spectroscopy and analysis of surface grain sizes providing indirect experimental support. The CVL??? s ability to crystallise thicker films more directly applicable to photovoltaic devices secures its viability as an alternative laser for photovoltaic applications. The through-the-glass doublesided irradiation and the stepwise crystallisation provide additional potential for increased process flexibility over XMR???s.

One of the poly-Si thin-film cells developed at the University of New South Wales (UNSW) is the EVA cell. In this work, SiN films for EVA cells as an antireflection/barrier coating were investigated. In addition, the effect of hydrogenation pre-treatment of solid phase crystallisation (SPC) on grain size and open-circuit voltage (Voc) was investigated. The SiN films deposited by PECVD were examined for uniformity of the thickness and the refractive index of the films across the position of the samples in the PECVD deposition system. A spectrophotometric analysis was used to determine these film properties. It was found that these properties were very uniform over the deposition area. Good repeatability of the depositions was also observed. A series of SiN film depositions by reactive sputtering were also performed to optimize the deposition process. Parameters adjusted during the deposition were nitrogen flow rate, substrate bias, and substrate temperature. By investigating the deposition rate, refractive index, and surface roughness of the films, the three deposition parameters were optimised. The effects of post SiN deposition treatments (a-Si deposition, SPC, RTA, and hydrogenation) on thickness and refractive index of both SiN films deposited by PECVD and reactive sputtering were investigated by using samples which have the same structure as the EVA cells. The thickness of the PECVD SiN films decreased about 6 % after all the treatments. On the other hand, the thickness reductions of the reactively sputtered SiN films were very small. The refractive index of the PECVD SiN films increased about 0.6 % after the treatments, whereas that of the reactively sputtered SiN films decreased 1.3 % after the treatments. As a possible method to improve the performance of EVA cells, hydrogenation of a-Si was investigated as a pre-treatment of SPC process. There were no obvious differences in the grainsize and the Voc of the EVA cells with and without the hydrogenation. Therefore it is likely that the hydrogenation pre-treatment of SPC does not have a beneficial effect on the performance of EVA cells.

Thin-film solar cells on glass substrates are likely to have a bright future due to the potentially low costs and the short energy payback times. Polycrystalline silicon (poly-Si, grain size &gt 1 pm) has the advantage of being non-toxic, abundant, and long-term stable. Glass as a substrate, however, limits the processing temperatures to ~600??C for longer process steps. Films with large grain size can be achieved by solid phase crystallisation (SPC), and especially by solid phase epitaxy (SPE) on seed layers, using amorphous silicon deposited at low temperatures as a precursor film. With SPC and SPE, the amorphous silicon film is typically crystallised at ~600??C over hours. During this anneal at atmospheric pressure -depending on the properties of the amorphous silicon film- ambient gas can percolate the film and can negatively affect the crystallisation. In this work, a high-vacuum anneal chamber was designed and built to allow the in-situ crystallisation of amorphous silicon films deposited on glass in a PECVD cluster tool. An important aspect of the design was the comfortable and safe operation of the vacuum anneal chamber to enable unattended operation. This was realised by means of a state-of-the-art, programmable temperature controller and a control circuit design that incorporates various safety interlocks. The chamber interior was optimised such that a temperature uniformity of 2-3K across the sample area was achieved. The chamber was calibrated and tested, and SPC and SPE samples were successfully crystallised. In initial SPC crystallisation experiments with solar cell structures, after post-deposition treatments, a 1 -sun open-circuit voltage of 465 mV was obtained, similar to furnace-annealed samples. In initial experiments with SPE solar cell structures, difficulties regarding the characterisation of the unmetallised solar cells with the quasi-steady-state open-circuit voltage method (QSSVOC) were encountered after post-deposition hydrogen treatment. A possible explanation for these difficulties is the contact formation with the metal probes. Furthermore, limiting factors of the QSSVOC method for the characterisation of unmetallised cells with high contact resistance values were investigated and, additionally, the accuracyof the QSSVOC setup was improved in the low light intensity range.

The focus of this thesis is to characterise the interactions between GLUT4-related SNARE proteins – syntaxin4, SNAP23 and VAMP2 – and a regulatory protein, Munc18c. GLUT4 is the primary insulin-regulated glucose transporter and is presentin fat and muscle cells. GLUT4 is held in intracellular pools of vesicles until it is transported to the cell surface upon insulin stimulation. Insulin initiates a cellular signalling cascade via the insulin receptor on the cell membrane, which in turn stimulates GLUT4 vesicles to move to the cell surface where they fuse to the plasmamembrane via SNARE proteins. SNAREs are membrane-anchored proteins present on both vesicle and target membranes that form a tight complex which brings themembranes together for fusion. Fusion of vesicles to the target membrane releases the vesicular cargo.SNARE-mediated membrane fusion is a conserved mechanism that controls many other vesicle fusion processes such as neurotransmitter release and yeast vesicular trafficking. However, the regulation of the SNARE mechanism is not fully understood. SNAREs can interact with many other proteins that could act as regulatory factors,and studies have focused primarily on a group of effector proteins called Sec1p/Munc18 (SM) proteins. SM proteins were discovered and characterised because they bind to one type of SNARE protein, syntaxin. The SM protein that interacts with the GLUT4-related SNARE, syntaxin4, is Munc18c.The aim of this thesis was to investigate Munc18c interactions with SNARE proteins, principally syntaxin4, using biochemical techniques with purified recombinant proteins. This work was carried out in several stages including: 1) development of methods to produce and purify GLUT4-related SNARE proteins, SNARE complexes and Munc18c, 2) development of an assay to quantify Munc18c interactions with binding partners using surface plasmon resonance, 3) investigation into interactions between Munc18c and SNARE ternary complex, 4) characterising Munc18c interactions with syntaxin4, and 5) developing a method to produce selenomethionine-containing Munc18c in a baculovirus system to be used in structural studies. The methods and outcomes of these experiments are described inthis thesis. There were two major outcomes from this work. Firstly, Munc18c interacts with SNARE ternary complex, and secondly, Munc18c requires only the N-terminal 29residues of syntaxin4 for an interaction to occur. These results were determined using pulldown assays with purified proteins, as well as other chromatographic methods to show that protein complexes were formed. The steps taken to develop these binding assays are also discussed. Initial crystallisation conditions forMunc18c-HIS and a peptide consisting of syntaxin4 residues 1-20 have been identified using crystallisation screens. The interactions determined for Munc18c binding to Sx4 are in direct contrast to those of neuronal SM protein, Munc18a, and its interaction with neuronal SNARE proteins - Munc18a does not bind to its ternary complex and binds to the entire cytoplasmic domain of Sx1a. Rather, the Munc18c:Sx4 interactions are similar to that for the yeast SM protein, Sly1p, which can interact with both its SNARE ternary complex and with its syntaxin via the Nterminal residues. Another interesting outcome of this research was that syntaxin4 binds to metals (cobalt and nickel). This finding represents the first reported for a syntaxin interacting with metals. Preliminary results indicate that un-tagged syntaxin4 can bind to cobalt resin, and to nickel immobilised on a chip. This interesting and novel property of syntaxin4 binding was serendipitously discovered while investigating conditions for the Munc18c assay. Overall, I have shown that Munc18c, the SM protein involved in GLUT4 trafficking, interacts with SNARE proteins in a different manner to its mammalian counterpart inneurons, Munc18a, and is more like Sly1p, a yeast ER-Golgi SM protein. Munc18c interacts with SNARE complexes and only the N-terminal residues of syntaxin4.These interactions demonstrate that the regulatory mechanism for SNARE-mediated fusion is conserved between yeast and mammals. This finding has several implications for the role of Munc18c in the exocytosis of GLUT4-containing vesicles. Munc18c could act at several stages in the fusion process via syntaxin4 binding.These interactions could involve binding to other proteins (such as synip or tomosyn), conformational switching of syntaxin4 or interaction with metal ions to induce conformational changes in the proteins. Finally, these studies of GLUT4 exocytosis contribute to our understanding of glucose transport disorders such as Type 2 diabetes and could one day pave the way for the design of therapeutic agents.