No / This paper presents a circuit model which is used to calibrate the performance of nonlinear RF energy conversion inside a high quality factor resonant cavity with a known nonlinear loading device. The nonlinear radiofrequency energy conversion can be detected by exciting the fundamental operating frequency and observing the second harmonic resonant frequency within a doubly resonant cavity. By implementing the proposed mathematical model, the required input power can be estimated to maximise the chance of detecting the weak second harmonic signal prior to carry out the measurement.

Realising Si-based electrically driven light emitters in a process technology compatible with mainstream microelectronics CMOS technology is key requirement for the implementation of low-cost Si-based optoelectronics and thus one of the big challenges of semiconductor technology. This work has focused on the development of microcavity enhanced silicon LEDs (MCLEDs), including their design, fabrication, and experimental as well as theoretical analysis. As a light emitting layer the abrupt pn-junction of a Si diode was used, which was fabricated by ion implantation of boron into n-type silicon. Such forward biased pn-junctions exhibit room-temperature EL at a wavelength of 1138 nm with a reasonably high power efficiency of 0.1%. Two MCLEDs emitting light at the resonant wavelength about 1150 nm were demonstrated: a) 1-lambda MCLED with the resonator formed by 90 nm thin metallic CoSi2 mirror at the bottom and semitransparent distributed Bragg reflector (DBR) on the top; b) 5.5-lambda MCLED with the resonator formed by high reflecting DBR at the bottom and semitransparent top DBR. Using the appoach of the 5.5-lambda MCLED with two DBRs the extraction efficiency is enhanced by about 65% compared to the silicon bulk pn-junction diode.

Les travaux présentés dans ce mémoire portent sur l’étude des plasmas d’hélium générés par micro-ondes en cavité résonnante à la pression atmosphérique et sur leurs applications en traitement de surfaces. Tout d’abord, un état de l’art sur les plasmas micro-ondes à la pression atmosphérique et leurs applications est présenté. Ensuite, un modèle collisionnel-radiatif de la décharge et de la post-décharge d’hélium pur est établi. Les résultats du modèle sont comparés aux mesures expérimentales obtenues à 2500 K et un jeu de sections efficaces et de constantes cinétiques valables pour ces conditions est proposé. Expérimentalement, des analyses par spectroscopie d’émission et d’absorption sont employées. La température du gaz est déterminée par la méthode du spectre rotationnel synthétique en fonction de la puissance, de la concentration et de la nature des impuretés introduites dans l’hélium. Il s’avère que le volume du plasma est un paramètre déterminant sur la température du gaz. La concentration du métastable He(23S), en décharge continue et pulsée, est déterminée par absorption laser. En décharge continue, la concentration du métastable est divisée par trois avec 360 ppm d’impureté, la nature de l’impureté n’ayant pas d’importance. En revanche, en post-décharge la nature de l’impureté est déterminante. Les mesures réalisées indiquent que He+ et non He2+ serait l’ion majoritaire. Concernant les applications de ce type de plasma, nous avons travaillé en post-décharge uniquement. Nous avons démontré la faisabilité du procédé de dépôt de SiOx à partir d’hexaméthyldisiloxane. Nous avons aussi montré que la nitruration du titane à haute température était possible / The present work deals with the study of helium microwave plasmas at atmospheric pressure generated in a resonant cavity and their applications in surface treatment. First of all, a state of art of microwave atmospheric pressure plasmas and their applications is presented. Next, a collisional-radiative model for pure helium discharge and post-discharge is described. The results of the model are compared to experimental data obtained at 2500 K and a coherent set of cross-sections and rate constants is obtained for these conditions. Emission and absorption spectroscopy diagnostics are employed to characterize the helium plasma. The gas temperature is determined by the rotational synthetic spectra method. The evolution of the gas temperature, as a function of the input power, the concentration and the nature of impurities in helium, is measured. It turns out that the plasma volume plays a significant role on the gas temperature. The He(23S) concentration is determined by laser absorption in pulsed and continuous mode. In continuous mode, the metastable concentration is divided by 3 with 360 ppm of impurity, regardless of the nature of the impurity. Nevertheless, during the post-discharge, in pulsed mode, the nature of the impurity plays an important role. These measurements support the idea that He+ and not He2+ is the main ion. Concerning the applications, only post-discharges are utilized. We demonstrate that deposition of SiOx using hexamethyldisiloxane as precursor can be efficient. We show that titanium nitriding at high temperature is possible

De nouveaux besoins dans le domaine des télécommunications par satellite ont amené les industriels du secteur à se pencher sur l’optimisation des ressources en créant des systèmes reconfigurables, capables d’adapter leur fonctionnement fréquentiel en cours de mission. Cette thèse s’intéresse plus particulièrement aux multiplexeurs et à la manière de les rendre agiles à travers les filtres qui les composent ainsi qu’une adaptation de leur architecture.Dans un premier temps, le présent manuscrit dresse l’état de l’art des dispositifs accordables réalisés par les équipes de recherche du monde entier, avant de proposer des solutions mettant en œuvre une topologie de multiplexage à coupleurs hybrides. Dans un second temps, des études sont présentées portant sur une pluralité de concepts de cavités ou d’éléments de couplage accordables. Certains de ces concepts sont ensuite sélectionnés et assemblés afin de former des fonctions de filtrage et de multiplexage accordables. La dernière partie présente ainsi deux multiplexeurs accordables, l’un permettant une reconfiguration en bande étroite, l’autre en bande large, le premier ayant donné lieu à une réalisation expérimentale. / New needs in the field of satellite telecommunications have led manufacturers in the sector to focus on optimizing resources by creating reconfigurable systems able to adapt their operating frequencyplan during the mission. This thesis focuses on multiplexers and how to make them agile through their architecture and the filters that compose them.This manuscript starts by realizing the state of the art oftunable filtering devices through analysis of contributions made by research teams around the world. Based on this state of art,solutions to the problematic are proposed using a hybrid coupler multiplexing topology. Then studies are presented on various tunable cavities or coupling elements concepts. Some of these concepts have been selected and assembled to form tunable filtering and multiplexing functions. The last part thus presents two tunable multiplexers, allowing narrowband or broadband reconfiguration. An experimental realization has also been conducted on the narrowband version.

Realising Si-based electrically driven light emitters in a process technology compatible with mainstream microelectronics CMOS technology is key requirement for the implementation of low-cost Si-based optoelectronics and thus one of the big challenges of semiconductor technology. This work has focused on the development of microcavity enhanced silicon LEDs (MCLEDs), including their design, fabrication, and experimental as well as theoretical analysis. As a light emitting layer the abrupt pn-junction of a Si diode was used, which was fabricated by ion implantation of boron into n-type silicon. Such forward biased pn-junctions exhibit room-temperature EL at a wavelength of 1138 nm with a reasonably high power efficiency of 0.1%. Two MCLEDs emitting light at the resonant wavelength about 1150 nm were demonstrated: a) 1-lambda MCLED with the resonator formed by 90 nm thin metallic CoSi2 mirror at the bottom and semitransparent distributed Bragg reflector (DBR) on the top; b) 5.5-lambda MCLED with the resonator formed by high reflecting DBR at the bottom and semitransparent top DBR. Using the appoach of the 5.5-lambda MCLED with two DBRs the extraction efficiency is enhanced by about 65% compared to the silicon bulk pn-junction diode.