The first chapter of this thesis describes the motivation behind using room temperature ionic liquids (RTILs) in gas sensor research and reviews current applications of RTILs in various sensors. The second chapter describes electrochemical polymerization of aniline in room temperature 1-butyl-3-methylimmidazolium ionic liquids without addition of any acid. It is shown that the polymerization of aniline in BMI(BF4) does require small but controlled amounts of water whereas the polymerization in BMI(PF6) and in BMI(TF2N) does not require any water addition. The third chapter describes the construction of reference electrodes for RTIL applications that have a known and reproducible potential versus the ferrocene/ ferrocenium couple. They are based on reference electrodes of the first kind, Ag/Ag+ couple type, or of the second kind, based on Ag/AgCl in M+Cl-. The stability, reproducibility, and temperature behavior of the two reference systems have been characterized. The fourth chapter describes the electrochemical preparation and spectral analysis of gold clusters by adding gold atoms one-by-one through polyaniline s ability to form a strong complex with chloroaurate at the protonated imine sites. Our results confirm that both the amount and the size of gold clusters affects the properties of the composite material. The fifth chapter describes the development and characterization of a CHEMFET sensing layer based on a composite of CSA-doped polyaniline (PANI), and the room temperature ionic liquid BMI(TF2N) for the sensing of ammonia gas. The work function responses of the cast films with and without IL are analyzed by step-wise changes of ammonia gas concentration from 0.5 to 694 ppm in air as a function of the mole fraction of IL to PANI. The PANI CSA/BMI(TF2N) layers shows enhanced sensitivities, lower detection limit and shorter response times. The final chapter describes the preparation and characterization of field-effect transistors with mixed ionic-electronic conductors that have been created by varying the ratio of room temperature ionic liquid and emeraldine salt of polyaniline. Transistor with high electronic conductivity (32mol% ES-PANI) and Au gate contact exhibited theoretical behavior of an IGFET; whereas, the purely ionic gate behaved irreproducibly, indicating that a capacitive divider has been formed in the gate.

Since 1994, South African education system has been undergoing continuous transformation which had an impact on the quality of teaching and learning. There appeared to be a huge underperformance in the High School and FET College learners which for many years forced Universities to embark on bridging courses in order to enroll new students. Furthermore, a misalignment of college’s National Technical Diploma (NATED) programmes that did not afford college graduates an opportunity to register with Universities nor Universities of Technology brought about the questioning of the quality of teaching and learning in the FET College sector. Tabling the unified quality improvement plans in education in South Africa, the Education Ministry introduced an integrated approach to measure teaching and learning with the view of identifying improvement strategies. However, the implementation of this integrated tool called the Integrated Quality Management System had educators and managers attaching ambiguous meanings to the system. The IQMS instrument is meant to be a dependable quality assurance tool to measure and improve the quality of teaching and learning. The ambiguity lies with educators and managers referring to IQMS as a means to acquire 1% pay progression and the possible return of the old apartheid systems’ inspectorate. This research study was promulgated by a concern on the effectiveness and efficiency of implementing the IQMS instrument to measure the quality of teaching and learning in South African FET sector. In exploring literature on the concept of quality teaching and learning in the FET sector in South Africa, the researcher identified that similar trends of integrating quality management systems in education are being followed globally. The difference to the South African system is the attachment of the salary progression of 1% as an incentive to performance. In view of the introduction of the new system of education and training, the researcher realized that ‘short cut’ processes were followed in preparing educators to be able to offer new education programmes using the OBE system of teaching and learning. That appeared to be another shortfall to the adequacy of implementing IQMS as a quality assurance instrument to measure the quality of teaching and learning in the FET sector in South Africa. In addition, there appeared to be conflicting trends in the FET sector where the same sector provided curriculum 2005 programmes for schools which differed from college programmes offering National Certificate Vocational {NC(V)}. Both sectors were expected to use IQMS as a tool to measure the quality of teaching and learning with the view of enhancing improvement thereof. Furthermore, the end product of the FET sector for both schools and colleges is the Further Education and Training Certificate (FETC). Unfortunately, it was difficult for the education department to achieve its objectives because time frames to prepare educators and the critical element of providing adequate human resources for the implementation of IQMS could not be met through Umalusi the national quality assurance body for the sector. The FET Sector which is expected to deliver Education and Training to produce quality students for HE sector and the world of work is faced with shortfalls of quality delivery. The driving force of this research study was to explore the dependability and adequacy of implementing IQMS as a quality assurance instrument to effectively and efficiently measure the quality of teaching and learning to meet the expected outcomes. It is in this regard that the researcher through empirical evidence realized that IQMS did not have theoretical grounding hence there are no principles, procedures or processes that govern the implementation of this very important system. In addition, the empirical evidence from the qualitative study proved that quality delivery of teaching and learning has been monitored using diverse assessment practices. A variety of assessment tools like the TQM and QMS which exist in FET Colleges with the summative IQMS in FET Schools of which the three practices are premised around Quality Management. Quality Management refers to a process where quality delivery in a school, college or any other organization is systematically managed to maintain the competence of the organization. It is in this regard that TQM, QMS and IQMS refer to Quality Assurance Practices in any organization that is geared to effective and efficient client relations. / Teacher Education / D.Ed. (Education Management)

Les biocapteurs ont pour objectif de détecter de faible quantité de biomolécules afin d'améliorer laqualité et la précocité des diagnostics médicaux. Parmi eux, les transistors à nanofils sont desdispositifs prometteurs, car ils permettent la détection électrique de biomolécules sans marquage avecune grande sensibilité et un temps de réponse court. Actuellement, la plupart de ces dispositifs utilisedes nanofils de silicium, qui peuvent être limités par une faible résistance chimique, ce qui entrainedes variations du signal en présence de solutions biologiques. Pour palier ces inconvénients, le carburede silicium (SiC) est un matériau prometteur déjà utilisé dans le domaine biomédical pour lafabrication ou le recouvrement de prothèses ou de vis médicales. Outre ses propriétés semiconductrices,ce matériau est biocompatible et montre une forte inertie chimique. Par conséquent, ilouvre une voie à l'intégration in-vivo des capteurs.L'objectif de cette thèse est d'élaborer des biocapteurs SiC à l'échelle nanométrique pour détecter desmolécules d'ADN. La première étape est la fabrication des transistors à base de nanofils SiC à grillearrière. Un procédé original de fonctionnalisation combiné avec la lithographie et aboutissant augreffage covalent de molécules sondes d'ADN a été mis au point. Finalement, la réponse des capteursa été mesurée entre chaque étape du protocole de fonctionnalisation. Les variations du signal lors desétapes de greffage et d'hybridation des molécules d'ADN démontrent la capacité de ces dispositifs àdétecter des molécules d'ADN. Des mesures complémentaires ont aussi montré la stabilité, lasélectivité et la réversibilité du dispositif. / Biosensors are designed to detect small quantities of biomolecules in order to improve the accuracyand earliness of medical diagnosis. Among them, nanowire transistors are promising devices, as theyallow the electrical detection of biomolecules without labeling with high sensitivity and a shortresponse time. Currently, most of these devices use silicon nanowires, which can be limited by a lowchemical resistance, which leads to signal variations in the presence of biological solutions. Toovercome these limitations, silicon carbide (SiC) is a promising material already used in thebiomedical field for the coating of prosthesis or bone screws. In addition to its semiconductingproperties, this material is biocompatible and shows a high chemical inertness. Therefore, it opens theway for in vivo integration of sensors.The goal of this thesis is to develop SiC biosensors at the nanoscale to detect DNA molecules. Thefirst step is the fabrication of SiC nanowire-based back gate transistors. A novel process combiningfunctionalization and lithography leading to the covalent grafting of DNA probe molecules has beendeveloped. Finally, the sensor response was measured between each step of the functionalizationprocess. The variations of the signal during the steps of grafting and hybridization of DNA moleculesdemonstrate the ability of these devices to detect DNA molecules. Additional steps have also shownthe stability, selectivity and reversibility of the device.

In the world we live in today, the international trade and economy is becoming more and more dependent on data. Data that can be transferred across borders and during the last couple of years there is an observable trend that the cross-border data flows is increasing. The increase of the cross-border data flows is a result of the vast boom in the global digitalization.  Businesses and enterprises can use the data accessible in multiple kinds of ways, follow and keep control of production chains, follow the demand of consumers, and make alterations to the products following the requests of the consumers. This is improving the efficiency and productivity of the businesses. The free flow of data across borders does not only have positive effect for the businesses, but also from a larger perspective, it also contributes to the welfare of countries, and provide new possibilities and opportunities. Despite the fact that the free flow of data has its great effects on both businesses and the welfare of states, states are imposing restrictions on cross-border data flows. The restrictions in place are of deferent kinds, some makes it mandatory to store or process data, while other restrictions are harsher and could provide a ban or cut off on cross-border data flow.  In the legal system of international investment law, the fair and equitable treatment standard is a standard found in treaties, bilateral and multilateral. The standard is protecting the forging investors.  If a state is enforcing a restriction with an effect equivalent to a ban on cross-border data flow, what is the relation of that restriction to the fair and equitable treatment standard?

This diploma thesis is dealing with the design of a DC / AC converter for the control of PMSM motors. In the first step, the type of motor and the possibilities of sensing the position of the rotor are described. Subsequently, the power section is designed and the losses, heating, and approximate efficiency of the inverter are calculated. In the following step, the processor is selected and individual communication and protection circuits are designed. At the same time, control algorithms are analyzed. The last part is describing the implementation of the PCB and the inverter as a whole.

In the course of the PhD thesis large area homogeneous strictly monolayer graphene films were successfully synthesized with chemical vapor deposition over both Cu and Si (with surface oxide) substrates. These synthetic graphene films were characterized with thorough microscopic and spectrometric tools and also in terms of electrical device performance. Graphene growth with a simple chemo thermal route was also explored for understanding the growth mechanisms. The formation of homogeneous graphene film over Cu requires a clean substrate. For this reason, a study has been conducted to determine the extent to which various pre-treatments may be used to clean the substrate. Four type of pre-treatments on Cu substrates are investigated, including wiping with organic solvents, etching with ferric chloride solution, annealing in air for oxidation, and air annealing with post hydrogen reduction. Of all the pretreatments, air oxidation with post hydrogen annealing is found to be most efficient at cleaning surface contaminants and thus allowing for the formation of large area homogeneous strictly monolayer graphene film over Cu substrate. Chemical vapor deposition is the most generally used method for graphene mass production and integration. There is also interest in growing graphene directly from organic molecular adsorbents on a substrate. Few studies exist. These procedures require multiple step reactions, and the graphene quality is limited due to small grain sizes. Therefore, a significantly simple route has been demonstrated. This involves organic solvent molecules adsorbed on a Cu surface, which is then annealed in a hydrogen atmosphere in order to ensure direct formation of graphene on a clean Cu substrate. The influence of temperature, pressure and gas flow rate on the one-step chemo thermal synthesis route has been investigated systematically. The temperature-dependent study provides an insight into the growth kinetics, and supplies thermodynamic information such as the activation energy, Ea, for graphene synthesis from acetone, isopropanol and ethanol. Also, these studies highlight the role of hydrogen radicals for graphene formation. In addition, an improved understanding of the role of hydrogen is also provided in terms of graphene formation from adsorbed organic solvents (e.g., in comparison to conventional thermal chemical vapor deposition). Graphene synthesis with chemical vapor deposition directly over Si wafer with surface oxide (Si/SiOx ) has proven challenging in terms of large area and uniform layer number. The direct growth of graphene over Si/SiO x substrate becomes attractive because it is free of an undesirable transfer procedure, necessity for synthesis over metal substrate, which causes breakage, contamination and time consumption. To obtain homogeneous graphene growth, a local equilibrium chemical environment has been established with a facile confinement CVD approach, inwhich two Si wafers with their oxide faces in contact to form uniform monolayer graphene. A thorough examination of the material reveals it comprises facetted grains despite initially nucleating as round islands. Upon clustering these grains facet to minimize their energy, which leads to faceting in polygonal forms because the system tends to ideally form hexagons (the lowest energy form). This is much like the hexagonal cells in a beehive honeycomb which require the minimum wax. This process also results in a near minimal total grain boundary length per unit area. This fact, along with the high quality of the resultant graphene is reflected in its electrical performance which is highly comparable with graphene formed over other substrates, including Cu. In addition the graphene growth is self-terminating, which enables the wide parameter window for easy control. This chemical vapor deposition approach is easily scalable and will make graphene formation directly on Si wafers competitive against that from metal substrates which suffer from transfer. Moreover, this growth path shall be applicable for direct synthesis of other two dimensional materials and their Van der Waals hetero-structures.:Contents Quotation v Kurzfassung vii Abstract xi Contents xiii Acronyms xvii 1 Aims and objectives 1 2 Introduction 5 2.1 Carbon allotropes 6 2.1.1 Hybridized sp 2 carbon nanomaterials 6 2.1.2 Graphene 7 2.2 Properties of graphene 8 2.2.1 Crystalline structure 8 2.2.2 Electrical transport 10 2.2.3 Optical transparency 11 2.2.4 Other properties 12 2.3 Graphene deposition methods 13 2.3.1 Synthesis approaches 13 2.3.2 Chemical vapor deposition 14 2.3.3 Substrate selection 15 2.3.4 Substrate pretreatments 16 2.3.5 Carbon feedstock 17 2.3.6 Thermal chemical vapor deposition 17 2.3.7 Plasma chemical vapor deposition 18 2.3.8 Transfer protocol 19 2.4 Chemical vapor deposition for graphene growth 21 2.4.1 Thermodynamics 22 2.4.2 Arrhenius plots 22 2.4.3 Activation energy 24 2.4.4 Growth kinetics 25 2.4.5 Reaction mechanisms over Cu 27 2.4.6 Reaction mechanisms over Ni 29 2.4.7 Reaction mechanisms over non-metals 31 2.4.8 Reaction mechanisms of free-standing graphene 35 2.5 Summary 35 2.6 Scope of the thesis 36 3 Experimental setup and characterization techniques 37 3.1 Experimental setup of chemical vapor deposition 37 3.2 Optical microscopy 39 3.3 Scanning electron microscopy 40 3.4 Atomic force microscopy 41 3.5 Transmission electron microscopy 42 3.5.1 Selected area electron diffraction 44 3.5.2 Dark field transmission electron microscopy 46 3.6 Raman spectroscopy 47 3.7 Ultraviolet-Visible spectrophotometry 49 3.8 Electrical transport measurements 49 4 CVD growth of graphene on oxidized Cu substrates 51 4.1 Motivation 52 4.2 Experimental protocol 53 4.3 Influence of Cu pretreatments on graphene formation 54 4.4 Influence of Cu oxidation on graphene growth 60 4.5 Effect of oxidation pretreatment on Cu surface cleaning 64 4.6 Summary 66 5 Chemo-thermal synthesis of graphene from organic adsorbents 67 5.1 Motivation 67 5.2 Experimental protocol 69 5.3 Influence of reaction temperature on graphene growth 75 5.4 Influence of reaction pressure on graphene growth 78 5.5 Influence of reaction flow rate on graphene growth 80 5.6 Summary 81 6 Monolayer graphene synthesis directly over Si/SiO x 83 6.1 Motivation 83 6.2 Experimental protocol 86 6.3 Influence of substrate confinement configuration 87 6.4 Time dependent evolution for graphene formation 91 6.5 Grain boundaries in graphene film 95 6.6 Bubble clustering of faceted graphene grains 98 6.7 Electrical and optical performance of graphene 100 6.8 Summary 102 7 Conclusions 103 8 Outlook 107 A Graphene synthesis over Cu and transfer to Si/SiO x substrate 111 B Chemo-thermal synthesis of graphene over Cu 115 C CVD graphene growth directly over Si/SiO x substrate 127 Bibliography 147 List of Figures 193 List of Tables 197 Acknowledgements 199 List of publications 203 Erklaerung 205 / Im Zuge dieser Doktorarbeit wurden großflächige und homogene Graphen-Monolagen mittels chemischer Gasphasenabscheidung auf Kupfer- (Cu) und Silizium-(Si) Substraten erfolgreich synthetisiert. Solche monolagigen Graphenschichten wurden mithilfe mikroskopischer und spektrometrischer Methoden gründlich charakterisiert. Außerdem wurde der Wachstumsmechanismus von Graphen anhand eines chemo-thermischen Verfahrens untersucht. Die Bildung von homogenen Graphenschichten auf Cu erfordert eine sehr saubere Substratoberfläche, weshalb verschiedene Substratvorbehandlungen und dessen Einfluss auf die Substratoberfläche angestellt wurden. Vier Vorbehandlungsarten von Cu-Substraten wurden untersucht: Abwischen mit organischen Lösungsmitteln, Atzen mit Eisen-(III)-Chloridlösung, Wärmebehandlung an Luft zur Erzeugung von Cu-Oxiden und Wärmebehandlung an Luft mit anschließender Wasserstoffreduktion. Von diesen Vorbehandlungen ist die zuletzt genannte Methode für die anschließende Abscheidung einer großflächigen Graphen-Mono-lage am effektivsten. Die chemische Gasphasenabscheidung ist die am meisten verwendete Methode zur Massenproduktion von Graphen. Es besteht aber auch Interesse an alternativen Methoden, die Graphen direkt aus organischen, auf einem Substrat adsorbierten Molekülen, synthetisieren konnen. Jedoch gibt es derzeit nur wenige Studien zu derartigen alternativen Methoden. Solche Prozessrouten erfordern mehrstufige Reaktionen, welche wiederrum die Qualität der erzeugten Graphenschicht limitieren, da nur kleine Korngrößen erreicht werden konnen. Daher wurde in dieser Arbeit ein deutlich einfacherer Weg entwickelt. Es handelt sich dabei um ein Verfahren, bei dem auf einer Cu-Substratoberfläche adsorbierte, organische Lösungsmittelmoleküle in einer Wasserstoffatmosphäre geglüht werden, um eine direkte Bildung von Graphen auf einem sauberen Cu-Substrat zu gewahrleisten.Der Einfluss von Temperatur, Druck und Gasfluss auf diesen einstufigen chemothermischen Syntheseweg wurde systematisch untersucht. Die temperaturabhängigen Untersuchungen liefern einen Einblick in die Wachstumskinetik und thermodynamische Größen, wie zum Beispiel die Aktivierungsenergie Ea, für die Synthese von Graphen aus Aceton, Isopropanol oder Ethanol. Diese Studien untersuchen außerdem die Rolle von Wasserstoffradikalen auf die Graphensynthese. Weiterhin wurde ein verbessertes Verständnis der Rolle von Wasserstoff auf die Graphen-synthese aus adsorbierten, organischen Lösungsmitteln erlangt (beispielsweise im Vergleich zur konventionellen thermischen Gasphasenabscheidung). Die direkte Graphensynthese mittels chemischer Gasphasenabscheidung auf Si-Substraten mit einer Oxidschicht (Si/SiOx ) ist extrem anspruchsvoll in Bezug auf die großflächige und einheitliche Abscheidung (Lagenanzahl) von Graphen-Monolagen. Das direkte Wachstum von Graphen auf Si/SiOx -Substrat ist interessant, da es frei von unerwünschten Übertragungsverfahren ist und kein Metall-substrat erfordert, welche die erzeugten Graphenschichten brechen lassen können. Um ein homogenes Graphenwachstum zu erzielen wurde durch den Kontakt zweier Si-Wafer, mit ihren Oxidflachen zueinander zeigend, eine lokale Umgebung im chemischen Gleichgewicht erzeugt. Diese Konfiguration der Si-Wafer ist nötig, um eine einheitliche Graphen-Monolage bilden zu können. Eine gründliche Untersuchung des abgeschiedenen Materials zeigt, dass trotz der anfänglichen Keimbildung von runden Inseln facettierte Körner erzeugt werden. Aufgrund der Bestrebung der Graphenkörner ihre (Oberflächen-) Energie zu minimieren, wird eine Facettierung der Körner in polygonaler Form erzeugt, was darin begründet liegt, dass das System idealerweise eine Anordnung von hexagonal geformten Körnern erzeugen würde (niedrigster Energiezustand). Der Prozess ist vergleichbar mit der sechseckigen Zellstruktur einer Bienenstockwabe, welche ein Minimum an Wachs erfordert. Dieser Prozess führt auch zu einer nahezu minimalen Gesamtkorn-grenzlänge pro Flächeneinheit. Diese Tatsache zusammen mit der hohen Qualität der resultierenden Graphenschicht spiegelt sich auch in dessen elektrischer Leistungsfähigkeit wider, die in hohem Maße mit der auf anderen Substraten gebildeten Graphenschichten (inklusive Cu-Substrate) vergleichbar ist. Darüber hinaus ist das Graphenwachstum selbstabschliessend, wodurch ein großes Parameterfenster für eine einfache und kontrollierte Synthese eröffnet wird. Dieser Ansatz zur chemischen Gasphasenabscheidung von Graphen auf Si- Substraten ist leicht skalierbar und gegenüber der Abscheidung auf Metallsubstraten konkurrenzfähig, da keine Substratübertragung notig ist. Darüber hinaus ist dieser Prozess auch für die direkte Synthese anderer zweidimensionalen Materialien und deren Van-der-Waals-Heterostrukturen anwendbar.:Contents Quotation v Kurzfassung vii Abstract xi Contents xiii Acronyms xvii 1 Aims and objectives 1 2 Introduction 5 2.1 Carbon allotropes 6 2.1.1 Hybridized sp 2 carbon nanomaterials 6 2.1.2 Graphene 7 2.2 Properties of graphene 8 2.2.1 Crystalline structure 8 2.2.2 Electrical transport 10 2.2.3 Optical transparency 11 2.2.4 Other properties 12 2.3 Graphene deposition methods 13 2.3.1 Synthesis approaches 13 2.3.2 Chemical vapor deposition 14 2.3.3 Substrate selection 15 2.3.4 Substrate pretreatments 16 2.3.5 Carbon feedstock 17 2.3.6 Thermal chemical vapor deposition 17 2.3.7 Plasma chemical vapor deposition 18 2.3.8 Transfer protocol 19 2.4 Chemical vapor deposition for graphene growth 21 2.4.1 Thermodynamics 22 2.4.2 Arrhenius plots 22 2.4.3 Activation energy 24 2.4.4 Growth kinetics 25 2.4.5 Reaction mechanisms over Cu 27 2.4.6 Reaction mechanisms over Ni 29 2.4.7 Reaction mechanisms over non-metals 31 2.4.8 Reaction mechanisms of free-standing graphene 35 2.5 Summary 35 2.6 Scope of the thesis 36 3 Experimental setup and characterization techniques 37 3.1 Experimental setup of chemical vapor deposition 37 3.2 Optical microscopy 39 3.3 Scanning electron microscopy 40 3.4 Atomic force microscopy 41 3.5 Transmission electron microscopy 42 3.5.1 Selected area electron diffraction 44 3.5.2 Dark field transmission electron microscopy 46 3.6 Raman spectroscopy 47 3.7 Ultraviolet-Visible spectrophotometry 49 3.8 Electrical transport measurements 49 4 CVD growth of graphene on oxidized Cu substrates 51 4.1 Motivation 52 4.2 Experimental protocol 53 4.3 Influence of Cu pretreatments on graphene formation 54 4.4 Influence of Cu oxidation on graphene growth 60 4.5 Effect of oxidation pretreatment on Cu surface cleaning 64 4.6 Summary 66 5 Chemo-thermal synthesis of graphene from organic adsorbents 67 5.1 Motivation 67 5.2 Experimental protocol 69 5.3 Influence of reaction temperature on graphene growth 75 5.4 Influence of reaction pressure on graphene growth 78 5.5 Influence of reaction flow rate on graphene growth 80 5.6 Summary 81 6 Monolayer graphene synthesis directly over Si/SiO x 83 6.1 Motivation 83 6.2 Experimental protocol 86 6.3 Influence of substrate confinement configuration 87 6.4 Time dependent evolution for graphene formation 91 6.5 Grain boundaries in graphene film 95 6.6 Bubble clustering of faceted graphene grains 98 6.7 Electrical and optical performance of graphene 100 6.8 Summary 102 7 Conclusions 103 8 Outlook 107 A Graphene synthesis over Cu and transfer to Si/SiO x substrate 111 B Chemo-thermal synthesis of graphene over Cu 115 C CVD graphene growth directly over Si/SiO x substrate 127 Bibliography 147 List of Figures 193 List of Tables 197 Acknowledgements 199 List of publications 203 Erklaerung 205

Ce manuscrit présente une étude expérimentale autour de la synthèse des nanotubes de carbone et de leurs possibles intégrations dans des dispositifs. Les remarquables propriétés électroniques et optiques des nanotubes en font un matériau de choix pour entre autres, la nanoélectronique. Néanmoins, l’intégration des nanotubes dans des dispositifs performants est encore aujourd’hui un défi. Cela repose principalement sur la difficulté d’obtenir de grandes quantités de nanotubes mono-paroi avec des propriétés uniformes, propriétés qui sont définies par la structure du nanotube (i.e. leur angle chiral et leur diamètre). Ainsi, réaliser des synthèses de nanotube de carbone avec un contrôle de leur structure représente un point clé pour le progrès dans ce domaine.Nous avons donc mis en place une nouvelle méthode de synthèse de nanotubes de carbone basée sur la chimie de coordination et le dépôt chimique en phase vapeur activé par filament chaud. Cette synthèse permet la conception de nombreux nouveaux catalyseurs bimétalliques pour la croissance des nanotubes de carbone. Comme le procédé mis en place est très générique, des études paramétriques peuvent être réalisées de manière à mieux comprendre l’influence des différents paramètres de la croissance sur la structure des nanotubes obtenue. Nous discuterons ici du rôle de la température et de la composition chimique du catalyseur. Les nanotubes obtenus sont principalement caractérisés par spectroscopie Raman et par microscopies électroniques.Afin de valider les observations obtenues par spectroscopie Raman, les nanotubes synthétisés ont aussi été intégrés dans des dispositifs de type transistor à effet de champ. Une analyse des performances des transistors en fonction des différents nanotubes utilisés dans le canal est présentée.Enfin, les nanotubes intégrés dans ces transistors ont été fonctionnalisés avec un chromophore de ruthénium. Nous avons montré que cette fonctionnalisation nous permet de moduler, grâce à une impulsion lumineuse, la conductivité du dispositif sur trois ordres de grandeur. / This manuscript presents an experimental study around the single wall carbon nanotubes (SWCNT) synthesis and their possible integration in nanodevices. The unique electronic and optical properties of carbon nanotubes make them a choice material for various applications, particularly in nano-electronics.Nevertheless, their integration in effective devices is still a challenge. This is mainly due to the difficulty to obtain large quantity of SWCNT with uniform properties, defined by their structure (i.e. chiral angle and diameter). Therefore, structure controlled growth of SWCNTs is a key point for progress in this field.Here, we established a new synthesis approach based on coordination chemistry and hot-filament chemical vapor deposition. This approach allows the design of various bimetallic catalyst nanoparticles for the SWCNT growth. As the synthesis process is generic, parametric study can be performed in order to better understand the influence of the various parameters on the structure of the as-grown SWCNTs. In particular, we will discuss the role of the growth temperature and the chemical composition of the catalyst on the final SWCNTs structure. The obtained SWCNTs are mainly characterized by Raman spectroscopy and electronic microscopy.In order to validate the observations performed by Raman measurement, the synthesized SWCNTs have been also integrated in field effect transistors (FET) devices. An analysis of the performance of the FET-device as a function of the SWCNTs used in its channel will be presented.Finally, SWCNTs integrated in these transistors have been functionalized with an inorganic chromophore of ruthenium.We demonstrate that the functionalization of the SWCNTs leads to a three order of magnitude reversible switch of the device conductivity triggered by visible light.

No description available.

La forte demande et le besoin d’intégration hétérogène de nouvelles fonctionnalités dans les systèmes mobiles et autonomes, tels que les mémoires, capteurs, et interfaces de communication doit prendre en compte les problématiques d’hétérogénéité, de consommation d’énergie et de dissipation de chaleur. Les systèmes mobiles intelligents sont déjà dotés de plusieurs composants de type capteur comme les accéléromètres, les thermomètres et les détecteurs infrarouge. Cependant, jusqu’à aujourd’hui l’intégration de capteurs chimiques dans des systèmes compacts sur puce reste limitée pour des raisons de consommation d’énergie et dissipation de chaleur principalement. La technologie actuelle et fiable des capteurs de gaz, les résistors à base d’oxyde métallique et les MOSFETs (Metal Oxide Semiconductor- Field Effect Transistors) catalytiques sont opérés à de hautes températures de 200–500 °C et 140–200 °C, respectivement. Les transistors à effet de champ à grille suspendu (SG-FETs pour Suspended Gate-Field Effect Transistors) offrent l’avantage d’être sensibles aux molécules gazeuses adsorbées aussi bien par chemisorption que par physisorption, et sont opérés à température ambiante ou légèrement au-dessus. Cependant l’intégration de ce type de composant est problématique due au besoin d’implémenter une grille suspendue et l’élargissement de la largeur du canal pour compenser la détérioration de la transconductance due à la faible capacité à travers le gap d’air. Les transistors à double grilles sont d’un grand intérêt pour les applications de détection de gaz, car une des deux grilles est fonctionnalisée et permet de coupler capacitivement au canal les charges induites par l’adsorption des molécules gazeuses cibles, et l’autre grille est utilisée pour le contrôle du point d’opération du transistor sans avoir besoin d’une structure suspendue. Les transistors monoélectroniques (les SETs pour Single Electron Transistors) présentent une solution très prometteuse grâce à leur faible puissance liée à leur principe de fonctionnement basé sur le transport d’un nombre réduit d’électrons et leur faible niveau de courant. Le travail présenté dans cette thèse fut donc concentré sur la démonstration de l’intégration 3D monolithique de SETs sur un substrat de technologie CMOS (Complementary Metal Oxide Semiconductor) pour la réalisation de la fonction capteurs de gaz très sensible et ultra basse consommation d’énergie. L’approche proposée consiste à l’intégration de SETs métalliques à double grilles dans l’unité de fabrication finale BEOL (Back-End-Of-Line) d’une technologie CMOS à l’aide du procédé nanodamascene. Le système sur puce profitera de la très élevée sensibilité à la charge électrique du transistor monoélectronique, ainsi que le traitement de signal et des données à haute vitesse en utilisant une technologie de pointe CMOS disponible. Les MOSFETs issus de la technologie FD-SOI (Fully Depleted-Silicon On Insulator) sont une solution très attractive à cause de leur pouvoir d’amplification du signal quand ils sont opérés dans le régime sous-le-seuil. Ces dispositifs permettent une très haute densité d’intégration due à leurs dimensions nanométriques et sont une technologie bien mature et modélisée. Ce travail se concentre sur le développement d’un procédé de fonctionnalisation d’un MOSFET FD-SOI comme démonstration du concept du capteur de gaz à base de transistor à double grilles. La sonde Kelvin a été la technique privilégiée pour la caractérisation des matériaux sensibles par le biais de mesure de la variation du travail de sortie induite par l’adsorption de molécules de gaz. Dans ce travail, une technique de caractérisation des matériaux sensibles alternative basée sur la mesure de la charge de surface est discutée. Pour augmenter la surface spécifique de l’électrode sensible, un nouveau concept de texturation de surface est présenté. Le procédé est basé sur le dépôt de réseaux de nanotubes de carbone multi-parois par pulvérisation d’une suspension de ces nanotubes. Les réseaux déposés servent de «squelettes» pour le matériau sensible. L’objectif principal de cette thèse de doctorat peut être divisé en 4 parties : (1) la modélisation et simulation de la réponse d’un capteur de gaz à base de SET à double grilles ou d’un MOSFET FD-SOI, et l’estimation de la sensibilité ainsi que la puissance consommée; (2) la caractérisation de la sensibilité du Pt comme couche sensible pour la détection du H[indice inférieur 2] par la technique de mesure de charge de surface, et le développement du procédé de texturation de surface de la grille fonctionnalisée avec les réseaux de nanotubes de carbone; (3) le développement et l’optimisation du procédé de fabrication des SETs à double grilles dans l’entité BEOL d’un substrat CMOS; et (4) la fonctionnalisation d’un MOSFET FD-SOI avec du Pt pour réaliser la fonction de capteur de H[indice inférieur 2]. / Abstract : The need of integration of new functionalities on mobile and autonomous electronic systems has to take into account all the problematic of heterogeneity together with energy consumption and thermal dissipation. In this context, all the sensing or memory components added to the CMOS (Complementary Metal Oxide Semiconductor) processing units have to respect drastic supply energy requirements. Smart mobile systems already incorporate a large number of embedded sensing components such as accelerometers, temperature sensors and infrared detectors. However, up to now, chemical sensors have not been fully integrated in compact systems on chips. Integration of gas sensors is limited since most used and reliable gas sensors, semiconducting metal oxide resistors and catalytic metal oxide semiconductor- field effect transistors (MOSFETs), are generally operated at high temperatures, 200–500 °C and 140–200° C, respectively. The suspended gate-field effect transistor (SG-FET)-based gas sensors offer advantages of detecting chemisorbed, as well as physisorbed gas molecules and to operate at room temperature or slightly above it. However they present integration limitations due to the implementation of a suspended gate electrode and augmented channel width in order to overcome poor transconductance due to the very low capacitance across the airgap. Double gate-transistors are of great interest for FET-based gas sensing since one functionalized gate would be dedicated for capacitively coupling of gas induced charges and the other one is used to bias the transistor, without need of airgap structure. This work discusses the integration of double gate-transistors with CMOS devices for highly sensitive and ultra-low power gas sensing applications. The use of single electron transistors (SETs) is of great interest for gas sensing applications because of their key properties, which are its ultra-high charge sensitivity and the ultra-low power consumption and dissipation, inherent to the fundamental of their operation based on the transport of a reduced number of charges. Therefore, the work presented in this thesis is focused on the proof of concept of 3D monolithic integration of SETs on CMOS technology for high sensitivity and ultra-low power gas sensing functionality. The proposed approach is to integrate metallic double gate-single electron transistors (DG-SETs) in the Back-End-Of-Line (BEOL) of CMOS circuits (within the CMOS interconnect layers) using the nanodamascene process. We take advantage of the hyper sensitivity of the SET to electric charges as well from CMOS circuits for high-speed signal processing. Fully depleted-silicon on insulator (FD-SOI) MOSFETs are very attractive devices for gas sensing due to their amplification capability when operated in the sub-threshold regime which is the strongest asset of these devices with respect to the FET-based gas sensor technology. In addition these devices are of a high interest in terms of integration density due to their small size. Moreover FD-SOI FETs is a mature and well-modelled technology. We focus on the functionalization of the front gate of a FD-SOI MOSFET as a demonstration of the DGtransistor- based gas sensor. Kelvin probe has been the privileged technique for the investigation of FET-based gas sensors’ sensitive material via measuring the work function variation induced by gas species adsorption. In this work an alternative technique to investigate gas sensitivity of materials suitable for implementation in DG-FET-based gas sensors, based on measurement of the surface charge induced by gas species adsorption is discussed. In order to increase the specific surface of the sensing electrode, a novel concept of functionalized gate surface texturing suitable for FET-based gas sensors are presented. It is based on the spray coating of a multi-walled-carbon nanotubes (MW-CNTs) suspension to deposit a MW-CNT porous network as a conducting frame for the sensing material. The main objective of this Ph.D. thesis can be divided into 4 parts: (1) modelling and simulation of a DG-SET and a FD-SOI MOSFET-based gas sensor response, and estimation of the sensitivity as well as the power consumption; (2) investigation of Pt sensitivity to hydrogen by surface charge measurement technique and development of the sensing electrode surface texturing process with CNT networks; (3) development and optimization of the DG-SET integration process in the BEOL of a CMOS substrate, and (4) FD-SOI MOSFET functionalization with Pt for H[subscript 2] sensing.

Planar electronic devices represent an attractive approach towards roll-to-roll printed electronics without the need for the sequential, precisely aligned, patterning steps inherent in the fabrication of conventional ‘3D’ electronic devices. Self-switching diodes (SSDs) and in-plane-gate field-effect transistors (IPG-FETs) can be patterned using a single process into a substrate precoated with semiconductor.These devices function in depletion mode, requiring the semiconductor to be doped in order for the devices to function. To achieve this, a reliable and controllable method was developed for doping organic semiconducting polymers by the immersion of optimally deposited films in a solution of dopant. The process was shown to apply both semicrystalline and air-stable, amorphous materials indicating that the approach is broadly applicable to a wide range of organic semiconductors.Simultaneously with the development of the doping protocol specialised hot-embossing equipment was designed and constructed and a high-yielding method of patterning the structures of IPG-FETs and SSDs was arrived at. This method allowed for consistent and reliable patterning of features with a minimum line-width of 200nm.Following the development of these doping and patterning processes these were combined to fabricate controllably doped, functioning planar devices. SSDs showed true zero-threshold rectification behaviour with no observed breakdown in the reverse direction up to 100 V. IPG-FETs showed switching behaviour in response to an applied gate potential and were largely free of detectable gate leakage current, verifying the quality of the patterning process.Furthermore, high-performance semiconducting polymer PAAD was synthesised and characterised in field-effect transistors as steps towards its use in planar electronic devices. It was also shown that this material could be doped using the developed immersion doping protocol and that this protocol was compatible with top-gated device architectures and the use of fluoropolymer CYTOP as a dielectric.