A redução das dimensões dos dispositivos semicondutores para escalas submicrométricas impõe diversos desafios no projeto de circuitos integrados. O impacto das variações intrínsecas afetando parâmetros elétricos cresce em importância à medida que a área dos dispositivos adentra a faixa nanométrica. Dentre essas variações estão flutuações nas tensões e correntes de terminal causadas pelas diferentes formas de ruído intrínseco dos dispositivos MOS. Este trabalho apresenta um estudo sobre o impacto do ruído elétrico no desempenho de circuitos MOS. Um novo modelo para simulação do Random Telegraph Signal (RTS) no domínio do tempo é utilizado. Uma metodologia de simulação para contabilizar o ruído térmico em simulações transientes também é proposta. A partir desses modelos de simulação de dispositivos, o trabalho de pesquisa analisa o impacto da variabilidade de parâmetros elétricos em nível de circuito. As simulações focam na caracterização da pureza espectral em osciladores em anel de sinal diferencial. Diversas topologias são apresentadas e posteriormente comparadas em termos do jitter no período de oscilação. / The shrinking of semiconductors devices dimensions to submicron scales introduces many challenges in integrated circuit design. The impact of intrinsic variability affecting electrical parameters increases in importance as transistors enter the nanometric range. Among these variations are fluctuations in terminal voltages and currents caused by different forms of intrinsic noise of MOS devices A new model for Random Telegraph Signal (RTS) simulation in time-domain is utilized. A simulation methodology to account for thermal noise effects in transient simulations is also proposed. Using these simulation models, this research work analyses the impact of electrical noise at circuit level. The simulations focus on the characterization of spectral purity in differential ring oscillators. Different topologies are presented and compared in terms of jitter in the period of oscillation.

A redução das dimensões dos dispositivos semicondutores para escalas submicrométricas impõe diversos desafios no projeto de circuitos integrados. O impacto das variações intrínsecas afetando parâmetros elétricos cresce em importância à medida que a área dos dispositivos adentra a faixa nanométrica. Dentre essas variações estão flutuações nas tensões e correntes de terminal causadas pelas diferentes formas de ruído intrínseco dos dispositivos MOS. Este trabalho apresenta um estudo sobre o impacto do ruído elétrico no desempenho de circuitos MOS. Um novo modelo para simulação do Random Telegraph Signal (RTS) no domínio do tempo é utilizado. Uma metodologia de simulação para contabilizar o ruído térmico em simulações transientes também é proposta. A partir desses modelos de simulação de dispositivos, o trabalho de pesquisa analisa o impacto da variabilidade de parâmetros elétricos em nível de circuito. As simulações focam na caracterização da pureza espectral em osciladores em anel de sinal diferencial. Diversas topologias são apresentadas e posteriormente comparadas em termos do jitter no período de oscilação. / The shrinking of semiconductors devices dimensions to submicron scales introduces many challenges in integrated circuit design. The impact of intrinsic variability affecting electrical parameters increases in importance as transistors enter the nanometric range. Among these variations are fluctuations in terminal voltages and currents caused by different forms of intrinsic noise of MOS devices A new model for Random Telegraph Signal (RTS) simulation in time-domain is utilized. A simulation methodology to account for thermal noise effects in transient simulations is also proposed. Using these simulation models, this research work analyses the impact of electrical noise at circuit level. The simulations focus on the characterization of spectral purity in differential ring oscillators. Different topologies are presented and compared in terms of jitter in the period of oscillation.

A redução das dimensões dos dispositivos semicondutores para escalas submicrométricas impõe diversos desafios no projeto de circuitos integrados. O impacto das variações intrínsecas afetando parâmetros elétricos cresce em importância à medida que a área dos dispositivos adentra a faixa nanométrica. Dentre essas variações estão flutuações nas tensões e correntes de terminal causadas pelas diferentes formas de ruído intrínseco dos dispositivos MOS. Este trabalho apresenta um estudo sobre o impacto do ruído elétrico no desempenho de circuitos MOS. Um novo modelo para simulação do Random Telegraph Signal (RTS) no domínio do tempo é utilizado. Uma metodologia de simulação para contabilizar o ruído térmico em simulações transientes também é proposta. A partir desses modelos de simulação de dispositivos, o trabalho de pesquisa analisa o impacto da variabilidade de parâmetros elétricos em nível de circuito. As simulações focam na caracterização da pureza espectral em osciladores em anel de sinal diferencial. Diversas topologias são apresentadas e posteriormente comparadas em termos do jitter no período de oscilação. / The shrinking of semiconductors devices dimensions to submicron scales introduces many challenges in integrated circuit design. The impact of intrinsic variability affecting electrical parameters increases in importance as transistors enter the nanometric range. Among these variations are fluctuations in terminal voltages and currents caused by different forms of intrinsic noise of MOS devices A new model for Random Telegraph Signal (RTS) simulation in time-domain is utilized. A simulation methodology to account for thermal noise effects in transient simulations is also proposed. Using these simulation models, this research work analyses the impact of electrical noise at circuit level. The simulations focus on the characterization of spectral purity in differential ring oscillators. Different topologies are presented and compared in terms of jitter in the period of oscillation.

The noise in the Langmuir Probe and Plasma Wave Instrument (LP-PWI) on board ESA:s future Jupiter satellite JUICE (Jupiter ICy Moons Explorer) was investigated. Thermal Johnson-Nyquist noise and shot noise, caused by fluctuations in the probe-plasma currents, were combined with the quasi-thermal noise (QTN) due to thermal fluctuations in the electric field in the plasma, using a small signal equivalent circuit model. The contributions and effects of each of the considered noise sources were examined and compared for a number of representative space plasma conditions, including the cold dense plasma of Ganymede's ionosphere and the hot tenuous plasma out in the Jovian magnetosphere. The results showed that in the cold dense plasma of Ganymede's ionosphere, the antenna was long compared to the Debye length and the quasi-thermal noise had a clearly pronounced peak and a steep high-frequency cut-off. For an antenna biased to 1 V with respect to the plasma, the shot noise due to the ambient plasma was the dominant source of noise. For a an antenna at the floating potential the photoelectron shot noise coalesced with the shot and Nyquist noises of the ambient plasma to form almost a single curve. In the hot tenuous plasma out in Jupiter's magnetosphere, the antenna was short compared to the Debye length and the QTN spectrum was much flatter, with little or no peak at the plasma frequency and a very weak high-frequency cut-off. For an antenna biased to 1 V, the shot noise due to photoelectron emission dominated at Callisto's orbital position whereas at Ganymede's and Europa's orbital positions the Nyquist and shot noises of the ambient plasma particles were the dominant noise components. For an antenna at the floating potential, the shot and Nyquist noises of the ambient plasma also dominated the output noise, except at Europa's orbital position, where the quasi-thermal noise was the largest noise component for frequencies at and above the plasma frequency. The numerical calculations were performed using MATLAB. The code was made available in a Git repository at https://github.com/eliasodelstad/irfuproj_JUICE_noise.

La microscopie à force atomique exploite les interactions entre une sonde et un échantillon. Les nanotubes de carbone représentent la sonde idéale, ils sont: fins, robustes, peu réactifs et ont un haut rapport d'aspect. L'utilisation à grande échelle des sondes à nanotubes de carbone passe par l'étude de leur comportement mécanique en contact avec une surface. Nous étudions deux types de sondes: les sondes avec nanotubes multiparois et les sondes avec nanotubes monoparois. Pour les nanotubes multiparois nous avons utilisé trois mode de fonctionnement AFM différents que sont les modes contact, modulation de fréquence et bruit thermique. Les résultats expérimentaux sont comparés à des modèles mécaniques que nous avons développés. Les études des nanotubes monoparois ont été réalisées à partir d'un AFM interférométrique. Ces mesures nous ont permis de déterminer l'énergie d'adhésion par unité de longueur d'un nanotube monoparoi sur des surfaces de graphite et mica.Enfin nous présentons deux applications des sondes AFM avec nanotube multiparoi. La première est un projet de sondes électrochimiques pour lesquelles un nanotube multiparoi sert de nanolocalisateur. La seconde est une étude par AFM d'une interface air-liquide de fluides complexes. / Atomic force microscopy exploits interactions between a probe and a sample. Carbon nanotubes represent the ideal probe; they are thin with a high aspect ratio, robustes and few reactive. The widespread use of carbon nanotube probes needs the study of their mechanical behavior in contact with a surface. We study two types of probes: probes with multiwalled nanotubes and probes with singlewalled nanotubes. For multiwalled nanotubes, we used three differents AFM modes that are contact, frequency modulation and thermalnoise. The experimental results are compared with mechanical models that we developed. Studies of singlewalled nanotubes have been produced from an interferometric AFM. These measures have enabled us to determine the adhesion energy per unit length of singlewalled nanotubes on graphite and mica surfaces.Finally we present two applications of AFM probes with multiwall nanotubes. The first is a project of electrochemical sensors for which a multiwall nanotube is used as a nanolocalisator. The second is a study by AFM of air-liquid interface of complex fluids.

No description available.

Die Transporteigenschaften eines Elektronengases mit reduzierter Dimensionalität werden von den Welleneigenschaften der Elektronen bestimmt. Dies ermöglicht es, verschiedene Quanteneffekte, wie Quanteninterferenz, zu beobachten. Im ersten Teil dieser Arbeit werden geätzte Quantenringe und eindimensionale (1D) Verengungen, basierend auf AlxGa1-xAs/GaAs-Heterostrukturen, hinsichtlich ihrer Transporteigenschaften untersucht. Messungen des thermischen Rauschens im Gleichgewichtszustand zeigen, dass der Erwartungswert mit den Rauschspektren aller 1D Verengungen übereinstimmt, jedoch um bis zu 60 % bei allen Quantenringen überschritten wird. Rauschmessungen im thermischen Nichtgleichgewicht ergeben, dass der Wärmefluss in Quantenringen mithilfe einer globalen Steuerelektrode (Topgate) an- und ausgeschaltet werden kann. Die magnetische Widerstandsänderung der Quantenringe zeigt Oszillationen, die dem Aharonov-Bohm-Effekt zugeordnet werden. Die Beobachtbarkeit dieser Oszillationen hängt stark von dem Abkühlvorgang der Probe ab und die Oszillationen zeigen Hinweise auf ein Schwebungsmuster sowie auf Phasenstarre. Im zweiten Teil der Arbeit werden die Oberflächenzustände von exfolierten Bi2Se3 Mikroflocken untersucht. Für Mikroflocken mit metallischen Temperaturabhängigkeiten des Widerstandes wurde schwache Anti-Lokalisierung beobachtet. Diese Beobachtung deutet darauf hin, dass sich die magnetische Widerstandsänderung weniger ausschließlich aus den 2D Oberflächenkanälen als vielmehr aus einem geschichtetem Transport von 2D Kanälen im Volumenkörper zusammensetzt. Eine Mikroflocke mit halbleitenden Eigenschaften zeigt keine Hinweise auf solch einen geschichteten 2D Transport und es wird angenommen, dass ihre magnetische Widerstandsänderung ausschließlich von den 2D Oberflächenzuständen verursacht wird. / The transport properties of an electron gas with reduced dimensionality are dominated by the electron’s wave nature. This allows to observe various quantum effects, such as quantum interference. In the first part of this thesis etched quantum rings and one-dimensional (1D) constrictions, based on AlxGa1-xAs/GaAs heterostructures, are investigated with respect to their transport properties. Thermal noise measurements in equilibrium show that the expectation value agrees with the noise spectra of all 1D constrictions but is exceeded by up to 60 % for the noise spectra of all quantum rings. Noise measurements in thermal non-equilibrium reveal that the heat flow can be switched on and off for a quantum ring by a global top-gate. The measured magnetoresistance of the quantum rings shows oscillations that are attributed to the Aharonov-Bohm effect. The observability of these oscillations strongly depends on the cooling process of the sample and the oscillations show indications of a beating as well as phase rigidity. In the second part of the thesis the surface states of exfoliated Bi2Se3 microflakes are studied. For microflakes that show a metallic temperature dependence of the resistance weak anti-localization is observed. This observation suggests that the magnetoresistance is a result of layered transport of 2D channels in the bulk rather than just the surface 2D channels. A microflake with semiconducting characteristics does not show indications of such a 2D layered transport and its magnetoresistance is considered to be carried by the 2D surface states only.

Les travaux présentés dans cette thèse portent sur l’imagerie computationnelle active et passive en micro-ondes. L’utilisation d’une cavité chaotique comme composants compressif est étudiée tant théoriquement (modèle mathématique, résolution algorithmique du problème inverse) et expérimentalement. L’idée sous-jacente est de remplacer un réseau d’antennes par une unique cavité réverbérante dont un réseau d’ouvertures sur la face avant permet de coder l’information spatiale d’une scène dans la réponse temporelle de la cavité. La réverbération des ondes électromagnétique à l’intérieur de la cavité fournit les degrés de liberté nécessaires à la reconstruction d’une image de la scène. Ainsi il est possible de réaliser en temps réel une image haute-résolution d’une scène à partir d’une unique réponse impulsionnelle. Les applications concernent la sécurité ou l’imagerie à travers les murs. Dans ce travail, la conception et la caractérisation d’une cavité chaotique ouverte sont effectuées. L’utilisation de ce dispositif pour réaliser en actif des images de cibles de diverses formes est démontrée. Le nombre de degrés de liberté est ensuite amélioré en modifiant les conditions aux limites grâce à l’ajout lampes fluorescentes. L’interaction des ondes avec ces éléments plasma permet de créer de nouvelles configurations de la cavité, améliorant ainsi la résolution des images. L’imagerie compressive est ensuite appliquée à la détection et localisation passive du rayonnement thermique naturel de sources de bruit, à partir de la corrélation des signaux reçus sur deux voies. Enfin, une méthode novatrice d’imagerie interférométrique de cibles est présentée. Elle est basée sur la reconstruction de la réponse impulsionnelle entre deux antennes à partir du bruit thermique micro-ondes émis par un réseau de néons. Ces travaux constituent une avancée vers les systèmes d’imagerie futurs. / The broad topic of the presented Ph.D focuses on active and passive microwave computational imaging. The use of a chaotic cavity as a compressive component is studied both theoretically (mathematical model, algorithmic resolution of the inverse problem) and experimentally. The underlying idea is to replace an array of antennas with a single reverberant cavity with an array of openings on the front panel that encodes the spatial information of a scene in the temporal response of the cavity. The reverberation of electromagnetic waves inside the cavity provides the degrees of freedom necessary to reconstruct an image of the scene. Thus it is possible to create a high-resolution image of a scene in real time from a single impulse response. Applications include security or imaging through walls. In this work, the design and characterization of an open chaotic cavity is performed. Using this device, active computational imaging is demonstrated to produce images of targets of various shapes. The number of degrees of freedom is further improved by changing the boundary conditions with the addition of commercial fluorescent lamps. The interaction of the waves with these plasma elements allows new cavity configurations to be created, thus improving image resolution. Compressive imaging is next applied to the passive detection and localization of natural thermal radiation from noise sources, based on the correlation of signals received over two channels. Finally, an innovative method of interferometric target imaging is presented. It is based on the reconstruction of the impulse response between two antennas from the microwave thermal noise emitted by a network of neon lamps. This work constitutes a step towards for future imaging systems.

This mémoire presents my current research interests in micro and nano-mechanics in a comprehensive manuscript. Our experimental device is first presented: this atomic force microscope, designed and realized in the Laboratoire de Physique de l'ENS Lyon, is based on a quadrature phase differential interferometer. It features a very high resolution (down to 10 fm/rtHz) in the measurement of deflexion, down to low frequencies and on a huge input range. The dual output of the interferometer implies a specific handling to interface common scanning probe microscope controllers. We developed analog circuitries to tackle static (contact mode) and dynamic (tapping mode) operations, and we demonstrate their performance by imaging a simple calibration sample. As a first application, we used the high sensitivity of our interferometer to study the mechanical behavior of micro-cantilevers from their fluctuations. The keystone of the analysis is the Fluctuation-Dissipation Theorem (FDT), relating the thermal noise spectrum to the dissipative part of the response. We apply this strategy to confront Sader's model for viscous dissipation with measurements on raw silicon cantilevers in air, demonstrating an excellent agreement. When a gold coating is added, the thermal noise is strongly modified, presenting a 1/f like trend at low frequencies: we show that this behavior is due to a viscoelastic damping, and we provide a quantitative phenomenological model. We also characterize the mechanical properties of cantilevers (stiffness and Elastic Moduli) from a mapping of the thermal noise on their surface. This analysis validates the description of the system in term of its normal modes of oscillations in an Euler-Bernoulli framework for flexion and in Saint-Venant approach for torsion, but points toward a refined model for the dispersion relation of torsional modes. Finally, we present peeling experiments on a single wall carbon nanotube attached to the cantilever tip. It is pushed against a flat substrate, and we measure the quasi-static force as well as the dynamic stiffness using an analysis of the thermal noise during this process. The most striking feature of these two observables is a plateau curve for a large range of compression, the values of which are substrate dependent. We use the Elastica to describe the shape of the nanotube, and a simple energy of adhesion per unit length Ea to describe the interaction with the substrate. We analytically derive a complete description of the expected behavior in the limit of long nanotubes. The analysis of the experimental data within this simple framework naturally leads to every quantity of interest in the problem: the force plateau is a direct measurement of the energy of adhesion Ea for each substrate, and we easily determine the mechanical properties of the nanotube itself.

La spectroscopie de bruit quasi-thermique est une méthode précise de déterminat-ion de la densité et de la température dans les plasmas spatiaux. Lorsqu'une antenne électrique est immergé dans un plasma, elle est capable de mesurer les fluctuations électrostatiques provoquées par le mouvement thermique des particules de plasma. Ces fluctuations sont détectées par la densité de puissance spectrale aux bornes de l'antenne, en observant un spectre à des fréquences comparables à la fréquence plasma électronique aussi bien pour les électrons que pour les protons, car le signal du proton est fortement décalé Doppler vers des fréquences plus élevées en raison de la vitesse de dérive du vent solaire. En plus d'induire le champ électrique fluctuant, une partie des électrons impactent sur la surface de l'antenne, ce qui provoque des perturbations de son potentiel électrique. Le signal provoqué par cette population est directement proportionnelle au flux d'électrons du plasma impactant l'antenne et est dominante si l'antenne a une grande surface. Dans ce travail, nous utilisons la théorie de l'orbite limite pour calculer le flux de particules impactantes pour un plasma non thermique décrit par fonction de distribution de vitesses $kappa$ ou Lorentzienne, communément mesurée dans le vent solaire. L'augmentation de la collecte de particules par des objets cylindriques et sphériques est quantifié et présenté en tant que fonction du potentiel électrostatique de surface et de la fraction des particules supra-thermique. La prise en compte de ces résultats théoriques est absolument nécessaire pour des mesures précises des paramètres du plasma à chaque fois que le bruit d'impact est l'élément dominant dans le spectre de puissance. Ceci est le cas pour STEREO, car les bruit d'impact est dominant pour cette sonde, en raison de la présence d'antennes courtes et épaisses. L'étude approfondie des données sur cette mission est motivée par le fait que ses analyseurs d'électrons sont défectueux depuis le lancement et aucune information sur les électrons thermiques n'est disponible. Les résultats obtenus sont vérifiés en comparant avec les résultats de Wind, montrant une bonne concordance entre les valeurs mesurées par les deux satellites. Les incertitudes des mesures sont déterminées par les incertitudes des instruments utilisés et sont estimés à environ $40%$. Le résultat final de ce travail sera l'établissement d'une base de données des moments d'électrons pour les deux sondes STEREO A et B qui couvriront toute la durée de la mission. Dans une seconde partie de la thèse, nous utilisons l'approche cinétique pour étendre la théorie du bruit quasi-thermique à des plasmas où les collisions des électrons avec les neutres jouent un rôle dominant. Cette technique permet de mesurer la densité et la température des électrons, et aussi la fréquence des collisions en tant que paramètres indépendants. Ceci est obtenu sur une large gamme de fréquences aussi bien en dessous qu'au dessus de la fréquence plasma, pour peu que le rapport entre la fréquence de collision et fréquence de plasma ne soit pas inférieur à 0.1. Les résultats présentés ici peuvent potentiellement être appliqués avec succès dans les plasmas de laboratoire et ionosphères non magnétisés, tandis que pour l'ionosphère de la Terre leur utilisation est limitée aux fréquences basses à cause de la présence d'un champ magnétique fort. / The quasi-thermal noise spectroscopy is an accurate method of determination of density and temperature in space plasmas. When an electric antenna is immersed into a plasma, it is able to measure electrostatic fluctuations caused by the thermal motion of plasma particles. These fluctuations are detected as the power spectral density at the antenna terminals, observing a spectrum at frequencies comparable to the electron plasma frequency for both electrons and protons, since the proton signal is strongly Doppler-shifted towards higher frequencies due to the solar wind drift velocity. Beside inducing the fluctuating electric field, some of the electrons are impacting the antenna surface, causing disturbances of the antenna electric potential. The signal caused by this population is directly proportional to the flux of plasma electrons impacting the antenna and is dominant if the antenna has a large surface area. In this work, we use the orbit limited theory to calculate the incoming particle flux for a non-thermal plasma described by $kappa$ velocity distribution function, commonly measured in the solar wind. The increase in the particle collection by cylindrical and spherical objects is quantified and presented as a function of the surface electrostatic potential and the fraction of supra-thermal particles. Including these results into the theory has turned out to be absolutely necessary for accurate measurements of the plasma parameters whenever the shot noise is the dominant component in the power spectrum. This is the case for STEREO because the impact noise is overwhelming on this probe, due to the presence of short and thick antennas. The comprehensive study of data on this mission is motivated by the fact that the electron analyzers are malfunctioning since launch and no information on thermal electrons is available. Results obtained are verified by comparing with the results from Wind, showing a good match between the values measured by the two spacecraft. Uncertainties of the measurements are determined by the uncertainties of the instruments used and are estimated to be around $40%$. The final outcome of this work will be establishing a database of the electron moments in both STEREO A and B that will be covering the entire duration of the mission. In the second part of the thesis, we use the kinetic approach to expand the theory of the quasi-thermal noise to plasmas where electron-neutral collisions play a dominant role. This technique is able to measure the electron density, temperature and the collision frequency as independent parameters using the wide frequency range both below and above the plasma frequency, if the ratio of the collisional to plasma frequency is not smaller than 0.1. The results presented here have can be potentially applied in laboratory plasmas and unmagnetized ionospheres, while at the ionosphere of Earth their use is limited to low frequencies due to the presence of the magnetic field.