Stimuli-responsive materials are changing the landscape of actuated materials, optoelectronics, molecular machines, solar cells, temporary memory storage, and biomedical materials. Specifically, photo-responsive polymers have gained acceleration in research and application since the last two decades in the form of a surface coating and micro-patterns. Light as a stimulus can be coherent, mono or polychromatic, tunable for power (intensity) and energy (wavelength), and has precise spatiotemporal control. Conventional surface coating techniques such as spin coating are unable to impart properties to the coatings in terms of sturdiness, homogeneity, uniformity over the complex surface, post deposition modification, and process efficiency. Also, in the field of photoreponsive polymers, there is no simple technique for surface-patterning of photo-responsive polymers, which is an important missing link between current research and future potential applications. This dissertation designs new strategies for light-mediated ring opening metathesis polymerization (ROMP) to synthesize a diverse class of stable photo-responsive polymers and coatings. Firstly, we propose a new synthetic route to functionalize surface-initiated ring opening metathesis polymerization (SI ROMP) coatings. The backbone of ROMP polymers has internal carbon-carbon double bonds which are potential sites to introduce additional functionalities like stimuli-responsive functional groups. We leverage these unsaturated bonds to incorporate functionalized side chains using thiol-ene click chemistry. Thiol-ene chemistry is a versatile approach to attach diverse functional groups at the site of a carbon-carbon double bond. This approach was tested by grafting 3 types of thiols with different functional tail groups and can be readily used for any polyolefin coatings. Secondly, oxidative degradation of SI ROMP coatings in the organic solvent is a common problem resulting in a decrease in the film thickness due to polymer chain cleavage. We incorporated a custom designed crosslinker to the polynorbornene (pNB) coatings to prepare in situ crosslinked pNB coatings. This approach provides a crosslinked coating of pNB with significantly increased stability against organic solvents by decreasing the film loss from 73 % to 28 %. Lastly, a novel approach of making photo-responsive polymer by light mediated ROMP is demonstrated. Light mediated control over rate of polymerization is the key feature required for patterning surface with photoresponsive polymers. We achieved this goal by designing and synthesizing a monomer that effectively controls the activity of the catalyst by temporarily deactivating it on irradiation with UV 365 nm light and reactivating it back by irradiation with blue 455 nm light to resume the ROMP.

Thermoelectric phenomena couple thermal and electric currents, allowing for solid-state conversion of heat into electricity. For decades Radioisotope Thermoelectric Generators have supplied power to NASA satellites and deep space probes. A more accessible application to consumers is the automotive industry's aspiration to incorporate thermoelectrics into active waste heat recovery systems. Higher power demands require these new thermoelectric devices to operate at higher temperatures and higher efficiencies, justifying new materials research. Recently, clathrates have gained interest for thermoelectric applications due to the unique properties they possess.These properties are directly related to their crystal structure. Therefore, clathrates are not only of interest from the standpoint of potential thermoelectric applications but are also of scientific interest as they presents an opportunity to investigate fundamental properties of group-IV elements in novel crystal structures. Clathrates are a class of novel open-structured materials in which molecules or atoms of one species are completely enclosed within a framework comprised of another species. This work presents a systematic investigation of the electrical properties of type I clathrate alloys, specifically Si-Ge alloys, for the first time. A series of Ba8Ga16-ySixGe30-x+y clathrates with varying Si content were synthesized and their structural and transport properties were studied. Two additional series of type I clathrates were also synthesized and characterized and their properties compared to those of the Si-Ge alloys in order to develop an understanding of their structure-property relationships. The increasing Si content correlates to a dramatic increase in Seebeck coefficient even as the resistivity decreases, suggesting the complex interaction between the Ba and the Si substitution within the Ga16Ge30 framework significantly modifies the band structure.

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.

Innovation in photovoltaic technology may offer cost competitive options to other energy sources and become a viable solution for the energy and environmental challenges of the 21st century. One proposed innovative technology is based on all-silicon tandem cells, which are constructed using superlattices consisting of environmental friendly Si and its compounds. The well and barrier materials in superlattices are restricted to silicon and silicon oxide during the present study. Single crystalline Si/SiO2 quantum wells (QWs) have been fabricated by thermal oxidation of silicon-on-insulator (SOI) wafers. It is found that oxide properties in QWs are important for SOI wafers prepared by the SIMOX (Separation by Implantation of Oxygen) technique. However, QWs fabricated from SOI wafers prepared by the ELTRAN (Epitaxial Layer TRANsfer) approach show the effect of quantum confinement without evidence of strong oxide interfacial transitions. In these wafers, evidence for an apparently ordered silicon oxide was found with 1.92?atomic fringe spacing along the (110) direction of the Si structure and with the thickness about 17?along the (100) direction of the Si structure. Luminescence wavelength ranges are from 700nm to 918nm depending on the Si thickness. The luminescence measurements on other positions of the sample show peak and shoulder spectra, which are explained by monolayer fluctuations in QW thicknesses, previously observed in III-V QWs and II-VI QWs. Si/SiO2 superlattices are fabricated by RF magnetron sputtering. Si density is the key issue in crystallizing the superlattice. High-density Si layers crystallize either under high temperature furnace annealing or rapid thermal process annealing. However, low density Si would not crystallize even at high temperature. Crystallized nanocrystals in the Si layers are observed by high resolution transmission electron microscopy (HRTEM) when the Si layer is thicker than 3nm. When Si layers are thinner than 3nm, the Si layers are discontinuous and finally deteriorate into small nanocrystals. The suitability of such superlattices for surface passivation and antireflection coatings is reviewed. Initial attempts to fabricate heterojunctions between Si wafers and Si/SiO2 superlattices resulted in open circuit voltage of 252mV. However, it is expected that better results would be obtained if Si/SiO2 superlattices were fully crystallized.

Thin-film solar cells are widely recognised to have the potential to compete with fossil fuels in the electricity market due to their low cost per peak Watt. The Thin-Film Group at the University of New South Wales (UNSW) is engaged in developing polycrystalline silicon (poly-Si) thin-film solar cells on glass using e-beam evaporation technology. We believe our solar cells have the potential of significantly lowering the manufacturing cost compared to conventional, PECVD-fabricated thin-film solar cells. After years of materials research, the focus of the Group??s work is now moving to the metallisation of evaporated solar cells. Minimising various kinds of losses is the main challenge of the cell metallisation procedure, within which the contact resistance is always a big issue. In this thesis, the contact resistance of aluminium contacts on poly-Si thin-film solar cells on glass is investigated. To the best of the author??s knowledge, this is the first ever contact resistance investigation of Al contacts on evaporated poly-Si material for photovoltaic applications. Various transmission line models (TLM) are employed to measure the contact resistance. An improved TLM model is developed to increase the measurement precision and, simultaneously, to simplify the TLM pattern fabrication process. In order to accommodate the particular requirements of poly-Si coated glass substrates, a TLM pattern fabrication process using photolithography is established. Furthermore, a Kelvin sense tester is set up to ensure an accurate measurement of the contact resistance. After establishment of the TLM technique at UNSW, it is successfully tested on singlecrystalline silicon wafer samples. The thermal annealing process of the contacts is also optimised. Then, the general behaviour of Al contacts on uniformly doped poly-Si films (i.e., no p-n junction) is investigated using the verified TLM technique. The long-term stability of the contacts is also studied. This is followed by an investigation of the contact resistance of the back surface field and emitter layers of different types of poly-Si thin-film solar cells. Finally, a novel contact resistance measurement model is proposed that is believed to be able to overcome the measurement bottleneck of the transmission line models.

An electron momentum spectrometer at the Australian National University has been used to study various aspects of different solid state systems. EMS is a transmission mode technique and involves the collision of the incident electron with a bound electron, after which both electrons are ejected and measured in coincidence. Through well defined reaction kinematics the complete valence spectral momentum density A(ɛ,q) can be measured. The spectrometer has been used to measure the spectral momentum densities (spectral functions) of single crystal targets, as well as targets in disordered states. A new spin polarised electron source was constructed and implemented in the ANU spectrometer, which was used to measure spin dependent features of ferromagnetic samples.¶ This thesis is divided into seven chapters, the first chapter is an introduction into the field of electron momentum spectroscopy, highlighting what has been measured before and how the technique has progressed to its present state. Some comparisons to other experimental techniques will be made.¶ The second chapter describes the ANU EMS spectrometer in detail. The technique requires some technical and advanced equipment that is often used in novel ways. The production of thin (20 nm) free standing targets will be detailed, along with the experimental chamber and electronics used to run the apparatus and collect data. The determination of the energy and momentum resolution of the experiment is also described.¶ The third chapter will detail the design and construction of the new spin polarised electron source. The results of commissioning and characterizing the new source will be presented.¶ Chapters four through six will present the measured results. The fourth chapter will detail the single crystalline measurements for the group eleven noble metals (Cu, Ag and Au). Each sample was measured along three high symmetry directions and compared to a DFT calculation using the LDA and a FP-LMTO basis. The fifth chapter will include the results from samples that were in disordered states, a measurement which is unique to the EMS technique. The polycrystalline and amorphous states of the Si and Ge semiconductors are presented and conclusions are made to the degree of difference in the results and to which theoretical approach to the unique amorphous state of the semiconductors best matches the EMS results. The sixth chapter includes results of ferromagnetic iron, measured using the spin polarised electron source. The spectrometer was used to measure spin-polarised electron-energy-loss-spectroscopy (SPEELS) and magnetic electron-Compton profiles. A theoretical investigation is also presented in chapter six which details the advancements required in the spin polarised electron gun to measure an accurate spin-polarised EMS spectra of a ferromagnetic Fe sample.¶ Chapter 7 includes the summary of all the results presented and conclusions reached from the comparison of the measured EMS spectra and various theoretical calculations. A discussion is presented about the future directions and possibilities of the EMS technique.

Community radio in Thailand is an alternative to public, commercial and state radio with unique characteristics in that listeners can participate at all levels. Community radio varies considerably in its definitions as well as serving several purposes depending on its role in the nation's media system. However, its fundamental philosophy is similar in that radio is used to serve the needs and the interests of the community. Access and participation in small-scale media may not only empower the voiceless, but also maintain local identity and cultures. The reformation of the Thai broadcasting media system by Section 40 of the 1997 constitution and the 2000 Broadcasting Act has increased the chance for some communities to use radio to fulfill their community development needs. The aims of this thesis are: to explore Thai community radio in the broader context of community radio internationally; to examine Thai broadcasting policies on community radio; to explore the development of Thai community radio in relation to the wider liberalisation of the media between 1998 and 2002; and to analyse similarities and differences in station management, programming and audience reception in the four different models of community radio that developed in a range of different provincial Thai community radio stations. A comparative case study using qualitative research methods was used to examine the four case studies, namely at Petchaburi (PRD, 1998) Nakhon Si Thammarat (MCOT, 1998), Roi Et (INN, 2000), and Kanchanaburi (people's radio, 200 I). The contribution of this thesis lies in its exploration of different models of Thai community radio so as to illustrate different interpretations by several stakeholders of community radio discourse, as well as reflecting the constraints on community broadcasting caused by the political economy of the broadcasting system and regulatory inconsistencies. It concludes that community radio has not yet contributed to a more empowered media because of several constraints. Thai community radio did not pursue real participatory communication to empower its listeners. It merely widened the public space for local communities to have more choices for information community-based programs with phone-in formats that provided twoway communication. Thai community radio has not created a wider liberalisation of the media, however, its development facilitated media democratisation through promoting the media reform process, and increasing the awareness of citizens' rights among ordinary people. Station manager and middle-class activists played important roles in putting forth local issues for public discussion. Increasing numbers of local people became alert to their rights to communicate as promised by the 1997 constitution, but unfortunately media reform lacked government support. The Thaksin government had an ambivalent attitude and contradictory policies towards community radio.

L'arbitrage est une étape essentielle du processus de gestion de l'évolution d'une organisation et de son système d'information, en particulier lors des études d'Urbanisme du SI. Le but de la méthode NENO est de fournir une assistance aux décideurs lors de la réalisation d'arbitrages dans ce contexte. L'arbitrage induit un processus de priorisation qui s'applique à de très grands ensembles d'exigences. Les approches de priorisation classiques en « requirement engineering » sont toutes confrontées à un problème de scalabilité lié au fait qu'elles considèrent les exigences individuellement. La multiplicité des alternatives et des critères de décisions présentés aux décideurs ne permet pas l'application des techniques classiques.<br />La méthode NENO consiste au contraire à regrouper les exigences (représentées sous la forme de buts fonctionnels) de manière à offrir qu'un nombre restreint d'alternatives aux décideurs. Ces regroupements effectués sont conformes aux dépendances entre buts, et s'exercent à différents niveaux d'abstraction. Conformément à la pratique au sein des organisations, les critères de décisions sont représentés sous la forme d'objectifs métiers que celles-ci doivent atteindre à moyen et long terme. Les buts sont individuellement évalués par des experts métier quant à leur faculté à satisfaire tout ou partie des objectifs métiers. Le recueil des évaluations est participatif, progressif et qualitatif. Un ensemble d'algorithmes permet de transposer et agréger les évaluations qualitatives en résultats quantitatifs dans le but de présenter les résultats sous la forme de priorités.

L'utilisation de différents niveaux de complexité dans les méthodes de la chimie théorique permet de discuter de la validité des modèles de reconstruction de la surface Si(100) et de créer des modèles de sous-oxydes. Notre étude ab-initio Hartree-Fock périodique est en faveur d'une reconstruction symétrique combinée à un arrangement anti-ferromagnétique 2x2 des spins des électrons des liaisons pendantes. Néanmoins la reconstruction asymétrique est quasi isoénergétique. Le traitement d'un large modèle moléculaire de sous-oxydes pseudo-périodique, permet de rendre compte des contraintes de la surface. L'importante relaxation trouvée dans cette étude est la combinaison d'une translation verticale et d'une rotation. Le réseau, la valence des espèces présentes peut influencer la cinétique de la relaxation. Le premier site d'oxydation est la liaison du dimère. Les atomes de silicium sont ensuite oxydés un par un.

Nous proposons un cadre conceptuel pour l'ingénierie des systèmes d'information (SIs) par composants. Ce cadre est basé sur les concepts d'hyperclasse et de composant de SI.<br />Le concept d'hyperclasse est une généralisation du concept de classe. Construite à partir d'un ensemble de classes connexe et complet, une hyperclasse permet d'exprimer des concepts que le niveau de classe n'aurait permis d'exprimer, et se comporte comme une classe : elle dispose d'hyperobjets, d'hyperattributs et d'hyperméthodes, équivalents des concepts d'objet, d'attribut et de méthode pour une classe. Un hyperobjet de l'hyperclasse est formé à partir des objets des classes de l'hyperclasse, atteints par navigation, à partir d'une classe particulière de l'hyperclasse qui est sa classe racine, et en suivant un graphe de navigation. Un hyperattribut de l'hyperclasse est un attribut de l'une de ses classes. Une hyperméthode est une méthode associée à l'hyperclasse qui peut avoir comme opérandes des hyperattributs, des hyperobjets, d'autres hyperméthodes de l'hyperclasse, les classes de l'hyperclasse, leurs objets et leurs méthodes de classes. Le concept d'hyperclasse offre une forme d'indépendance entre la structure du SI et ses traitements.<br />Un composant de SI est une entité autonome et cohérente, dans un modèle de SI, qui regroupe les représentations des espaces informationnel et opérationnel associés à une zone de responsabilité. Il est défini à partir d'une hyperclasse, d'un ensemble de transactions et d'un ensemble de règles d'intégrité du SI. La notion de transaction est associée à une activité productrice ou consommatrice d'informations dans un processus de prise de décision. Les règles d'intégrité sont définies sur un SI pour garantir sa cohérence durant son exploitation.<br />Les concepts d'hyperclasse et de composant de SI sont munis d'ensembles complets d'opération d'évolution. Ils sont définis indépendamment des méthodes, des langages et des technologies dans lesquelles le SI est implanté.<br />Le cadre conceptuel que nous proposons permet notamment de prendre en charge les situations de recouvrement de composants de SI, leur évolution, l'évolution du SI et ses répercussions sur ses composants.