Le graphène, une monocouche de graphite, est composé d'atomes de carbone avec une structure en nid d'abeilles. Ses propriétés exceptionnelles ont attiré un intérêt mondial, dont le Prix Nobel de Physique en 2010. Le graphène épitaxié sur métal à rapidement été identifié comme un moyen de production de graphène de haute qualité de taille métrique, et est le sujet d'intenses activités de recherche en sciences de surface pour caractériser ses propriétés. En outre, ces études concernent aussi des systèmes plus complexes avec pour base le graphène, par exemple les réseaux ordonnés de nanoparticules à sa surface. Tout cela a mené à l'étude de la croissance, de la structure et des défauts du graphène épitaxié avec un grande variété de techniques expériementales, tel que la microscopie par effet tunnel, spectroscopie par photo-émission résolue en angle ou encore la microscopie électronique à basse énergie. Ce travail de recherche se concentre sur le graphène obtenu par croissance sur la surface (111) d'un monocristal d'iridium dans des conditions d'ultra vide et étudié avec plusieurs techniques de mesure par diffraction (diffraction de surface des rayons X, diffraction des rayons X en incidence rasante, réflectivité des rayons X et diffraction des électrons à haute énergie en réflexion). Ces expériences ont été faites au synchrotron européen ESRF à Grenoble, en France. La première partie de cette étude a été de déterminer la structure du graphène à l'échelle atomique. Le système montre une tendance à la commensurabilité, mais sa structure précise dépend fortement des conditions de préparation et de la température appliqué au système. En outre, en combinant des techniques de diffraction à haute résolution, une caractérisation précise de la structure, qui fait débat dans la littérature, est dévoilée. Le système étudié présente aussi une surperstructure, typique du graphène épitaxié, nommé moiré pour ses similarités avec l'effet optique du même nom. Celle-ci est utilisée comme gabarit pour faire croître des nanoparticules monodisperses à la surface en réseau auto-organisé. Durant cette étude, trois types de nanoparticules ont été examinés, des particules de platine de deux tailles différentes et des particules composées de platine et de cobalt. Ces systèmes hybrides présentent un fort degré d'organisation, partiellement hérité de la superstructure du moiré. Les nanoparticules forme une interaction forte avec leur support et elles subissent des contraintes de surface causées par leurs petites tailles. Par ailleurs, les nanoparticules de platine-cobalt, dont la croissance est en deux étapes, gardent une structure en couche et non une structure d'alliage métallique. / Graphene, a monolayer of graphite, is composed of carbon atoms arranged in a honeycomb lattice. Its exceptional properties have attracted a worldwide interest, including the Novel Prize in Physics in 2010. Epitaxial graphene on a metal was rapidly identified as an efficient method for large-area production of high quality graphene, and also was the matter of intense activities exploiting surface science approaches to address the various properties of graphene and of advanced systems based on graphene, for instance ordered lattice of metal nanoparticles on graphene. This resulted in the study of growth, structure and defects of epitaxial graphene on a wide variety of substrates with various techniques such as scanning tunneling microscopy, angle-resolved photoemission spectroscopy or low-energy electron microscopy. This work focuses on graphene grown on the (111) surface of iridium in ultra-high vacuum conditions and studied with several diffraction techniques (surface X-ray diffraction, grazing incidence X-ray diffraction, X-ray reflectivity, and reflection-high energy electron diffraction). These experiments were performed at the European Synchrotron Radiation Facility in Grenoble, France. The first step in our study was to determine the structure of graphene at the atomic scale. The system was found to have a tendency to commensurability, but that the precise structure depends on temperature and on preparation conditions. Moreover, with the combination of high resolution diffraction techniques, a precise characterization about the debated structure of graphene perpendicular to the surface was unveiled. The system, exhibits a superstructure, typical of epitaxial graphene, called a moiré, as an equivalent of the moiré effect in optics. This is used as a template to grown nanoparticles on top of the system to achieve the self-organisation of monodisperse nanoparticles. In this study, three type of nanoparticles were investigated, two different size of pure platinum ones and bimetallic ones, platinum and cobalt. These hybrid systems show very high degree of order, partly inherited by the superstructure lattice. The nanoparticles were found to strongly bond to their support, experience substantial surface strain related to their small size, and that bimetallic ones grown in a sequential manner retain a chemically layered structure.

Orientador: Aleardo Junior Manacero / Banca: Maurício Araújo Dias / Banca: Marcos Antônio Simplício Júnior / Resumo: O desenvolvimento de tecnologias móveis tem criado oportunidades para uso de aplicações remotas executando em dispositivos como smartphones. Para algumas dessas aplicações é essencial que a autenticação seja feita de modo seguro e eficiente. Nesse sentido surge o uso da tecnologia NFC (Near Field Communication) para obter segurança para transações executadas em aplicativos móveis. Esse tipo de aplicação é bastante interessante para a realização de comércio eletrônico, bem como controle de acesso a informações sigilosas, como dados bancários, por exemplo. Neste trabalho, apresentam-se dois protocolos para fazer a autenticação de dispositivos através de etiquetas NFC, com técnicas de criptografia assimétrica usando algoritmos de curvas elípticas. Ao longo do texto são apresentados os principais conceitos sobre NFC, criptografia e a classe de web services REST (Representational State Transfer), que serve como padrão para a construção dos protótipos dos protocolos Protecting Touch aqui desenvolvidos. Os detalhes sobre a implementação desses protocolos são também apresentados, assim como resultados de experimentos para sua avaliação / Abstract: The appearance of mobile technologies created opportunities for remote applications running in devices such as smartphones. In some of these applications it is essential that authentication have to be performed in a secure and ecient way. In this sense the use of NFC (Near Field Communication) technology came to provide safety to transactions executed through mobile applications. This kind of application is rather attractive to perform electronic commerce, as well as access control for sensitive data, such as banking accounts. In this work it is presented two protocols for user authentication through NFC tags, using asymmetric cryptography by elliptic curves. Throughout the text we present the main concepts about NFC, cryptography and the web services REST (Representational State Transfer), which is used as the building framework for the prototypes of the Protecting Touch protocols presented here. Details about the protocols implementation are also presented, as well as results from the evaluation experiments of these protocols / Mestre

Near field communication (Nfc), a contact-range and short-lived message exchange technology, has in recent years become popular in relation to payment-cards, key-cards and ski-passes. With the release of, in particular, the Google Nexus S, which is capable of reading and writing Nfc tags as well as exchanging messages between devices by touch, the roles of consumers have changed from carriers of passive cards to that of active readers. This publicly available hardware technology, embedded into relatively cheap connected smartphones, creates a new field of possibilities in which a complete and complex Nfc-based system can be developed solely by means of software. In this thesis work, the research is in relation to the field of Nfc, ranging from the physical characteristics of the technology to the design of the Nfc API on the Android platform. Nfc-based apps, library and systems are designed, developed and evaluated in terms of performance. The Android apps which are implemented are WiFi and Bluetooth connectors as well as an Nfc-sensor value visualizer. Additionally, two full systems are developed which consists of an Android app, backend server, database and web or PC-client frontend. These two systems are: a web-based high-performance live statistical visualizer of Nfc sensor values and an Nfc-scan based product endorsement, Like-event, presenting the picture and name of a user endorsing a product on the in-store advertisement displays on top of the ads. The system for scanning, distributing and presenting statistics on sensor-values from a specially crafted NfcV-enabled sensor is evaluated in terms of performance along the chain of events starting at the Nfc tag introduction and being dispatched on the mobile phone and ending with the calculations and plot-generation carried out by the browser connected to the backend via a WebSocket. The evaluations show that in a use-case in which the user holds a tablet in one hand and an Nfc-enabled smartphone in the other, the user would experience a mean-delay of 515 milliseconds between putting the device against an NfcV-sensor and seeing the statistical plot, containing the last 1000 values, updated in the browser on the tablet. Additionally, the user would experience a mean-delay of 74 milliseconds between the values being presented on the mobile device itself until they are presented on the tablet in the case of constant streaming from an NfcV connected sensor. The conclusion is that this delay of 74 milliseconds is sufficiently low for the user to feel that the devices are tightly coupled, making it natural to pay attention to the tablet when scanning sensors. Possible use-cases for this include a technician walking between built-in passive NfcV sensors on the factory floor or a nurse walking between patients wearing bandages with built-in passive health-sensors. Finally, the work is discussed in terms of ethics and social impact as development in the tele-healthcare field continues, and a set of Nfc-based applications are suggested including Nfc-tags for interactive product customization, company car management and app deployment.

Un défi actuel dans le domaine de l'optique est de mieux comprendre les effets de champ proches optiques des systèmes et de pouvoir agir dessus. C'est dans ce contexte que j'explore tout au long de cette thèse ces notions appliquées aux milieux 3D diélectriques désordonnés et aux films désordonnés métal-diélectriques. Pour les milieux 3D, nous avons choisi une approche par un montage de microscopie de champ proche pour faire la mesure du champ proche optique. Nous avons pour cela dû faire un travail en amont sur la préparation des échantillons pour éviter les artefacts de mesure. Ces mesures ont révélés des structures intéressantes. Nous avons ensuite étudié les modes optiques sur les films métal-diélectriques et montré qu'il existe des modes étendus pour certaine valeurs de la faction surfacique de métal déposée. Nous avons quantifié leur extension par la mesure de la longueur d'interaction et mesuré des valeurs de l'ordre de la dizaine de microns, suffisant pour être contrôlé depuis le champ lointain. Ces mesures ont ouvert la voie au contrôle du front d'onde du faisceau incident dans l'objectif de la focalisation en champ proche de la lumière. Ceci a pu être réalisé grâce à l'utilisation d'un modulateur spatial de lumière pour le contrôle du front d'onde et à un signal non-linéaire de luminescence à deux photons pour la mesure du champ proche optique. Nous obtenons la focalisation en champ proche de l'énergie d'un facteur supérieur à dix. Enfin, la technique de microscopie de champ proche a pu être implémentée et couplée au contrôle de front d'onde et une première optimisation a pu être obtenue. Cela reste néanmoins un travail préliminaire. / One important challenge to address in the optical field is a better understanding of the optical near field of systems and how we can interact with them from the far-field. It is in this regard that I studied and controlled of the near field of both 3D disordered dielectric media and metal-dielectric disordered films. For 3D media, we used a near-field microscope to measure the optical field on their surface. To reach a free-artefact measure, we had to carefully prepare the sample by minimising the rugosity. In a second part, we studied optical modes on metal-dielectric films et we showed that it exists extended modes for some specific values of metal filling fraction of the sample. Extension of the modes has been quantified by measuring the interaction length and has been found in the order of 10 $\mu$m, enough to allow a far field control of the modes. These measurements opened the way for wavefront control of the incident beam in order to focus light in the near field of the sample. We use a spatial light modulator to control the incident wavefront and a non-linear signal (two photons luminescence - TPL) for the near-field measurement of the optical field. We could reach focusing of the energy by a factor more than ten. Finally, the SNOM technique has been coupled to the wavefront shaping system and we get preliminary measurements of optimisation in the near-field by this technique.

Dans le cadre de la guerre électronique en environnement marin, on cherche généralement à améliorer la furtivité d'un navire militaire afin de le rendre plus difficile à détecter et à localiser. Pour cela, il faut réduire la valeur de sa Surface Équivalente Radar (SER) afin de la rendre négligeable face aux perturbations apportées par l'environnement. La pratique a montré que la valeur de la SER mesurée est fortement influencée par l'environnement. Les estimateurs développés à ce jour offrent de bonnes performances pour déterminer la SER d'une cible navale de petite dimension mais deviennent imprécis pour un objet de grande taille placé dans un milieu inhomogène tel que l'environnement marin. Notre objectif est de proposer une nouvelle méthode de calcul de la SER qui prend en considération la nature volumique de la cible ainsi que les phénomènes de propagation intrinsèques à l'environnement marin. Une dyade de Green associée à la propagation d'une onde radioélectrique dans un conduit d'évaporation en présence d'une mer lisse et parfaitement conductrice, est alors développée et proposée pour calculer la SER de cibles navales de grandes dimensions. / In the naval electronic warfare, it is necessary to improve the stealth of military vessels in order to make them more difficult to be detected and be located. For that, the Radar Cross Section (RCS) value must be reduced to be negligible compared to the environment’s clutter. Experience has shown that the value of the measured RCS is strongly influenced by the environment. Nowadays, estimators developed offer good performance to determine the RCS of small naval targets but become inaccurate for large objects placed in inhomogeneous medium such as the marine environment. Our goal is to propose a new RCS estimation method which takes into account large targets and propagation phenomena in martime environment. A dyadic Green function, related to the radio wave propagation in an evaporation duct over smooth and perfectly conducting sea, is then developed and proposed to calculate the RCS of large naval targets.

Aujourd'hui les circuits intégrés commerciaux sont de plus en plus utilisés dans les satellites de télécommunication ou d'observation. En effet les contraintes économiques imposent l'usage de circuits non durcis aux radiations. Ceci, associé au fait que la technologie évolue entrainant une baisse de consommation et donc une diminution des marges de susceptibilité électromagnétique, les rendent plus sensibles à la fois aux interférences électromagnétiques et à la dose ionisante. Cet ensemble met en péril la mission des satellites. Ce travail de thèse est donc précurseur dans le domaine de la fiabilité combinée vis à vis de la dose ionisante et des signaux hautes fréquences (HF) sur des transistors bipolaires destinés aux applications basse fréquence. Nous avons tout d'abord observé la modification du comportement d'un transistor bipolaire discret lorsqu'il est soumis à une agression sinusoïdale continue (CW) dans la gamme 100 MHz - 5 GHz. Cette forme de signal nous a permis d'observer la réponse du transistor dans un régime établi. Il est important de noter que cette modification du comportement a lieu même pour des fréquences du signal d'interférence assez éloignées de la gamme de fréquence de fonctionnement du transistor. Nous avons pu alors mettre en évidence les différents mécanismes physiques mis en jeu. Ensuite nous avons étudié l'influence de différents paramètres : fréquence et puissance du signal d'interférence, boîtier du transistor, valeurs des éléments du circuit de polarisation, sur la réponse du transistor soumis à l'agression CW. Un critère simple permettant de prévoir le comportement du transistor sous agression CW est proposé. Nous avons ensuite étudié l'influence de la dose ionisante sur le comportement du transistor sous agression CW. Après avoir observé la modification du comportement statique du transistor suite à l'irradiation avec une source de cobalt 60, nous avons analysé l'évolution des grandeurs électriques du transistor sous agression HF, pour différentes valeurs de doses totales déposées. Nous avons donc pu monter que la dose ionisante influence effectivement le comportement du transistor sous agression. Enfin, nous avons soumis le transistor à une autre forme d'agression haute fréquence : un signal sinusoïdal modulé par un signal impulsionnel. Grâce à ce type de signal, nous avons pu faire une analyse du comportement transitoire du transistor, et mettre en évidence l'importance des capacités, à la fois internes et externes au composant. Ici encore la dose ionisante influence les comportements. / Nowadays, economic constraints push space and aeronautical industries to use Commercial Off The Shelf (COTS) components, even though natural space environment constitutes a real challenge for electronic reliability due to ionizing particles. In addition to this problem, technological advancements lead to a decrease in device consumption inducing smaller electromagnetic susceptibility margins. Hence, integrated circuits are more sensitive to both Electromagnetic Interferences (EMI) and ionizing dose, which may threaten satellite missions. This thesis reveals precursor work in the field of combined ionizing dose and high frequency (HF) interferences on bipolar transistors designed for low frequency applications. Classical discrete low frequency bipolar transistors biased at integrated-circuit level of currents are put under study. A change of the voltage output when the device is subject to a continuous sine aggression (CW) in the range 100 MHz - 5 GHz is observed. This CW waveform allows an analysis of the response of the transistor in a steady state. It is important to note that the change in behavior of the transistor occurs even for interference frequency bands way higher than the operating frequencies of the device. We identified the different physical mechanisms involved during high frequency interference injection: rectification and current crowding. Then we studied the influence on the behavior under interference of different parameters: frequency and power of the interference signal, low frequency and RF frequency package of the transistor, values of elements of the bias circuit. A simple criterion to predict the way of change in the output voltage of the transistor is proposed. The same experiments were conducted on the transistors irradiated with a cobalt 60 source. We highlighted the importance for high-frequency susceptibility of the change induced by ionizing dose near the emitter base junction. Hence the susceptibility must be considered for different bias operations for different ionizing dose rates. Finally, our interest focused on another type of HF interference: a sine wave modulated by a pulse signal. With this type of signal, the transient behavior of the transistor under interference is analyzed. It highlights the importance of internal and external capacitances of the device on its response. Here again ionizing dose influences the electromagnetic susceptibility of the transistor.

Le développement de dispositifs optiques intégrés dans des domaines tels que l'information quantique et la détection de molécules est actuellement dirigé vers l'intégration de nanosources (NS) sur des systèmes sur puce avec faible pertes de propagation. Cette thèse montre une contribution à la conception, à la fabrication et à la caractérisation de structures photonique-plasmoniques en vue de l'intégration d'une seule NS sur des puces optiques à travers le spectre visible. Nous recherchons à optimiser l’efficacité d’excitation et de collection de l'émission de la fluorescence d'une NS en combinant un nano-prisme en or et une structure formée par une couche de dioxyde de titane (TiO2) et un guide d'ondes à échange d'ions (IEW) sur verre. Le couplage entre les modes permet un transfert efficace de l'énergie entre un mode faiblement confiné dans l'IEW vers un mode plasmonique confiné dans un volume effectif de quelques nanomètres cubes. Ce mode confiné interagit avec une NS en améliorant son émission de fluorescence par l'effet de facteur Purcell. En utilisant le théorème de réciprocité de l'électromagnétisme, nous avons étudié le cas réciproque où la lumière émise par la NS peut être collectée dans les modes photoniques du IEW.La caractérisation a été réalisée en champ lointain et en champ proche avec en particulier l'utilisation d'un microscope optique de champ proche à sonde diffusante (SNOM). Nous avons proposé une configuration SNOM qui permet d'imiter l'interaction d'une NS et des systèmes guidés, cartographiant la densité locale des modes guidés (LDOM) / The development of integrated optical devices in areas such as quantum information and molecular sensing is currently directed towards the integration of nanosources (NS) into systems on a chip with low propagation losses. This thesis shows a contribution on the design, fabrication, and characterization of photonic-plasmonic structures towards the integration of a NS on optical chips across the visible spectrum. We pursue the efficient excitation and collection of the fluorescence emission of a NS by making use of the interaction between an electromagnetic field concentrator (gold nanoprism) and an integrated optics structure formed by a high-index layer of titanium dioxide (TiO2) and a low-contrast index ion exchanged waveguide on glass (IEW). The coupling mode allows an efficient transfer of the energy between a weakly confined mode in the IEW and a plasmonic mode confined in an effective volume of few cubic nanometers. This confined mode interacts with a NS enhancing its florescence emission through Purcell factor effect. Using the reciprocity theorem of electromagnetism, we studied the reciprocal case where the light emitted by the NS can be collected into the photonic modes of the IEW.The characterization was performed in the far and in the near field with the use of a scanning near-field optical microscopy (SNOM). We proposed a SNOM configuration that allows us to imitate the interaction of a NS and guided systems, mapping the local density of guided modes (LDOM)

Near-field Acoustical Holography is a tool that is conventionally used to visualize sound fields through an inverse process in a three-dimensional space so that either sound field projections or sound source localization can be performed. The visualization is conducted by using sound pressure measurements taken in the near-field region close to the surface of the unknown sound source. Traditional Fourier-based Near-field Acoustical Holography requires a large number of measurement inputs to avoid spatial truncation effects. However, the use of a large number of measurements is usually not feasible since having a large number of microphones is costly, and usually the array is limited in size by the physical environment, thus limiting the practicality of this method. In the present work, because of the desire to reduce the number of microphones required to conduct acoustical holography, a method known as Statistically Optimized Near-field Acoustical Holography initially proposed by Steiner and Hald was analyzed. The main difference between the present work and the concept mentioned by Steiner and Hald is the cylindrical coordinate system employed here for the purpose of experimenting on a bladeless fan, which resembles a cylindrical structure and which could be assumed to be a cylindrical source. The algorithm was first verified <i>via</i> simulations and measurements, and was then applied to experimental data obtained <i>via</i> pressure measurements made with a cylindrical microphone array. Finally, suggestions for noise control strategies for the bladeless fan are described, based on the measurement results.<br>

Wireless Sensor Network (WSN) have the potential to greatly affect every part of industrial and people’s lifestyle. For this reason, iPack VINN Excellence Center contributes to wireless tracking platform for fresh food and lifestyle. Every new idea or technology is attempted to integrate to the WSN for more efficient, better user experience and lower power consumption. Meanwhile Near Field Communication (NFC), a short-range wireless connectivity technology, which can make communication easily,safety and intuitively arousing iPack interest. So this master thesis focus on integrating NFC technology into existing systems to build a NFC-enable Wireless Sensor Network system. And with thissystem, only one simple touch, data from sensor node can be transmitted to mobile phone or tablet. Furthermore parameters of sensor node also can be configured easily by using above devices. So basically the NFC peer-to-peer communication protocol is mainly used. To implement and test the functions of the demonstration, a sets of hardware is needed to chosen and bought. How to design the system without changing old WSN is very tricky. To design a NFC adapter which can connect existing WSN with NFC part is thesolution of this thesis. So the main task was designing a NFC adapter which could be connected with either mobile phone/tablet or sensor node. It was the NFC adapter that makes mobile phone/tablet or sensor node NFC enabled. For the connection method, the high speed UART interface was chosen to connect with sensor node. The architecture of NFC adapter includes two main parts, A NFC chip (PN532) from NXP and a MCU(VNC2) from FTDI. The PN532 uses its antenna to send or receive data with different NFC protocols. The VNC2 is used to store sensor collected data and sends command though UART to control the PN532. Learning to use the PN532 was a tough task during the thesis work. Both official manuals and demo application are helpful for understanding the PN532 controlling. In addition, We analysed the sniffer data from demo application and code from NXP software design kit (SDK). which helped us to know the process of the PN532 peer-to-peer communication. After learning from official application, user manual and monitoring software/hardware design kid applications, we began to design our own hardware suitable SDK for the NFC adapter. At first we connected the hardware parts. When hardware connection was ready, we wrote and tested the firmware for VNC2 platform. Then due to the reason that Windows is more stable than our build VNC2 platform system at that moment, we wrote our own software design kid for NFC adapter under Windows OS first. The basic idea of software design kid is easy to use, modify and integrate into any other platforms. At the end of the thesis project, we integrated our own SDK into VNC2. When integration was done, a lot of stability and performance validation were done. Based on the result of testing, we optimized and modified our SDK and tested it again. This thesis project basically handles out a new ideal of integrating NFC to existing wireless sensor network to make WSN NFC enable. To prove the idea, we made a demo to show the enhanced sensor node and the results are satisfied. However there still has a lot of works and a lot of improvement should can be done in the future.

Over the past decades, technological advancements have made everyday objects smart, and naturally, these developments have reached the packaging industry too. Packaging equipped with sensors and chips can provide new experiences to its customers and one of the technologies that has shown its potential to contribute to this is Near Field Communication (NFC). Previous implementations of NFC in product packaging were limited to higher-end products. However, production costs of the chips have dropped substantially and has led to more adaptations. With more and more products using the technology, more consumers will get exposed to NFC- enabled packaging. Generation Z is one of those consumer groups. Thus, this study aimed to explore how NFC technology embedded in product packaging can influence the user experience for Generation Z and their relationships with brands. To achieve this goal, a qualitative approach was implemented, and 5 semi-structured interviews were conducted to get an understanding of the members of the generation’s view on NFC-enabled packaging. Emerging themes included added value, brand image, ease of use, right product, and environmental concerns. The findings from this study revealed the potential of NFC-embedded packaging and highlights the benefits it can provide to Generation Z but also several pain points and considerations.