abstract: Programmable Metallization Cell (PMC) is a technology platform which utilizes mass transport in solid or liquid electrolyte coupled with electrochemical (redox) reactions to form or remove nanoscale metallic electrodeposits on or in the electrolyte. The ability to redistribute metal mass and form metallic nanostructure in or on a structure in situ, via the application of a bias on laterally placed electrodes, creates a large number of promising applications. A novel PMC-based lateral microwave switch was fabricated and characterized for use in microwave systems. It has demonstrated low insertion loss, high isolation, low voltage operation, low power and low energy consumption, and excellent linearity. Due to its non-volatile nature the switch operates with fewer biases and its simple planar geometry makes possible innovative device structures which can be potentially integrated into microwave power distribution circuits. PMC technology is also used to develop lateral dendritic metal electrodes. A lateral metallic dendritic network can be grown in a solid electrolyte (GeSe) or electrodeposited on SiO2 or Si using a water-mediated method. These dendritic electrodes grown in a solid electrolyte (GeSe) can be used to lower resistances for applications like self-healing interconnects despite its relatively low light transparency; while the dendritic electrodes grown using water-mediated method can be potentially integrated into solar cell applications, like replacing conventional Ag screen-printed top electrodes as they not only reduce resistances but also are highly transparent. This research effort also laid a solid foundation for developing dendritic plasmonic structures. A PMC-based lateral dendritic plasmonic structure is a device that has metallic dendritic networks grown electrochemically on SiO2 with a thin layer of surface metal nanoparticles in liquid electrolyte. These structures increase the distribution of particle sizes by connecting pre-deposited Ag nanoparticles into fractal structures and result in three significant effects, resonance red-shift, resonance broadening and resonance enhancement, on surface plasmon resonance for light trapping simultaneously, which can potentially enhance thin film solar cells' performance at longer wavelengths. / Dissertation/Thesis / Ph.D. Electrical Engineering 2011

Mode switches are used to partition the system’s behavior into different modes to reduce the complexity of large embedded systems. Such systems is said to operate in multiple modes where each mode corresponds to a specific application scenario, are called Multi-Mode Systems (MMS). Normally, a different piece of software is executed for each mode. At a specific time, the system can be in one of the predefined modes and is switched from one mode to another upon some condition. A mode switch mechanism (or mode change protocol) is used to transform the system from one mode to another at run-time.In this thesis we have used a hierarchical scheduling framework to implement a multi-mode system, called Multi-Mode Hierarchical Scheduling Framework (MMHSF). A two-level Hierarchical Scheduling Framework (HSF) has already been implemented in an open source real-time operating system, FreeRTOS, to support temporal isolation among real-time components. The main contribution in this thesis is the extension of the HSF with the multi-mode feature with the emphasis of doing minimal changes in the underlying operating system FreeRTOS and its HSF implementation. Our implementation uses fixed-priority preemptive scheduling at both local and global scheduling levels and idling periodic servers. The implementation now supports different modes of the system which can be switched at run-time Each subsystem and task exhibit different timing attributes for different modes, and upon a Mode Change Request (MCR) the task-set and timing interfaces of the whole system (including subsystems and tasks) are changed. A Mode Change Protocol specifies the way to change the system-mode. An application may not only need to change a mode but also a different mode change protocol semantic. For example, the mode change from normal to shutdown can allow all the tasks to be completed before the mode is changed. While changing a mode from normal to emergency may require aborting all the tasks instantly. In our work, both the system mode and the mode change protocol can be changed at run-time. We have implemented three different mode change protocols to switch from one mode to another: the Suspend/resume protocol, Abort protocol and Complete protocol. These protocols increase the flexibility of the system, letting the users to select the way they want to switch to the new mode.The implementation of MMHSF is tested and evaluated on an AVR-based 32 bit board EVK1100 with an AVR32UC3A0512 micro-controller. We have tested the behavior of each mode of the system and for each mode change protocol. We also provide the results for the performance measures of all mode change protocols in the thesis.

Ce travail est consacré à la synthèse et à la caractérisation de commutateurs et de fils moléculaires. La première partie est une étude bibliographique qui présente les avantages et les applications des unités moléculaires utilisées dans le contexte de l’électronique moléculaire. La deuxième partie de ce manuscrit traite de la préparation, des études électrochimiques et photophysiques de complexes de ruthénium bimétalliques portant un coeur triarylamine. Le but est ici de moduler la luminescence de ce cœur en changeant l’état redox des groupements acetylure de ruthénium. Dans la troisième partie, des combinaisons de précurseurs de complexes de Ln (Ln = Eu ou Yb) et de groupements vinyl-ruthénium redox-actifs ont été formées afin de moduler la luminescence des centres Ln via l’oxydation des groupements vinyl-ruthénium. La quatrième partie décrit l'association d'un précurseur de complexe de Ln (Ln = Eu ou Yb) à un ligand portant une unité dithienylethene (DTE), afin de commuter l'émission de lumière du centre Ln. Ces composés ont été synthétisés avec succès et leur luminescence a été reversiblement modulée par irradiation lumineuse. Dans la dernière partie, nous décrivons la synthèse d'une série de fils moléculaires composée de complexes bis(acetylure) de ruthénium (II) terminés par des groupes fonctionnels amine, et comprenant un complexe bimétallique photochrome avec une unité DTE. Ces molécules ont été conçues de manière à être insérées entre deux électrodes de graphène pour étudier leur conductance dans les différents états redox. En outre, le complexe photochrome doit pouvoir permettre la commutation de la conductance par voie optique et électrochimique dans des jonctions moléculaires de graphène. / This work is devoted to the synthesis and characterization of novel molecular switches and wires that incorporate ruthenium organometallic moieties. First, a bibliographic chapter presents the advantages and applications of the building blocks used in the following chapters and discuss the general context of molecular electronics. The second part of this manuscript deals with preparation, electrochemical and photophysical studies of bimetallic ruthenium complexes bearing a triarylamine core. The goal is to modulate the luminescence of this core by changing the states of the redox-active ruthenium acetylide moieties. In the third part, combinations of Ln (Ln = Eu or Yb) complexes and redox-active ruthenium vinyl bipyridine moieties were formed in order to tune the luminescence of Ln center via oxidation of the redox-active ruthenium vinyl moieties. The fourth part describes an association of a Ln (Ln = Eu or Yb) precursor and a ligand bearing a dithienylethene (DTE) unit, in order to commute the light emission of the Ln center. These DTE-Ln compounds were successfully synthesized and their luminescence was reversiblely modulated by photo irradiation. In the last part, we report the synthesis of a series of redox-active molecular wires, which are ruthenium (II) bis(σ-arylacetylide) complexes terminated with amine functional groups, one of them including a photochromic DTE unit. These molecules are designed to covalently bridge a gap between graphene electrodes for probing the electrochemical gating of conductance via oxidation of the molecules. Furthermore, the photochromic complex should allow combined optical and electrochemical conductance switching in single molecule graphene junctions.

Nanoscale materials have many potential advantages because of their quantum confinement, cost and producibility by low-temperature chemical methods. Advancement of theoretical methods as well as the availability of modern high-performance supercomputers allow us to control and exploit their microscopic properties at the atomic scale, hence making it possible to design novel nanoscale molecular devices with interesting features (e.g switches, rectifiers, negative differential conductance, and high magnetoresistance). In this thesis, state-of-the-art theoretical calculations have been performed for the quantum transport properties of nano-structured materials within the framework of Density Functional Theory (DFT) and the Nonequilibrium Green's Function (NEGF) formalism. The switching behavior of a dithiolated phenylene-vinylene oligomer sandwiched between Au(111) electrodes is investigated. The molecule presents a configurational bistability, which can be exploited in constructing molecular memories, switches, and sensors. We find that protonation of the terminating thiol groups is at the origin of the change in conductance. H bonding at the thiol group weakens the S-Au bond, and thus lowers the conductance. Our results allow us to re-interpret the experimental data originally attributing the conductance reduction to H dissociation. Also examined is current-induced migration of atoms in nanoscale devices that plays an important role for device operation and breakdown. We studied the migration of adatoms and defects in graphene and carbon nanotubes under finite bias. We demonstrate that current-induced forces within DFT are non-conservative, which so far has only been shown for model systems, and can lower migration barrier heights. Further, we investigated the quantum transport behavior of an experimentally observed diblock molecule by varying the amounts of phenyl (donor) and pyrimidinyl (acceptor) rings under finite bias. We show that a tandem configuration of two dipyrimidinyl-diphenyl molecules improves the rectification ratio, and tuning the asymmetry of the tandem set-up by rearranging the molecular blocks greatly enhances it. It has been recently demonstrated that the large band gap of boronitrene can be significantly reduced by carbon functionalization. We show that specific defect configurations can result in metallicity, raising interest in the material for electronic applications. In particular, we demonstrate negative differential conductance with high peak-to-valley ratios, depending on the details of the material, and identify the finite bias effects that are responsible for this behavior. Also, we studied the spin polarized transport through Mn-decorated topological line defects in graphene. Strong preferential bonding is found, which overcomes the high mobility of transition metal atoms on graphene and results in stable structures. Despite a large distance between the magnetic centers, we find a high magnetoresistance and attribute this unexpected property to very strong induced π magnetism. Finally, the results obtained herein advance the field of quantum electronic transport and provide significant insight on switches, rectification, negative differential conductance, magnetoresistance, and current-induced forces of novel nanoscale materials.

<p>Increasing demand for higher power density in many applications such as Hybrid Electric Vehicles (HEVs) and renewable power generation has led to great technological advances in power electronics. To meet this increasing demand, a power semiconductor device needs to have low on resistance, increased switching speeds and reduced total system cost. Silicon (Si) power devices have been used for several decades but they are fundamentally limited by material properties. Silicon carbide (SiC) as a power semiconductor material offers superior electrical and thermal properties compared to silicon, which it can replace in a large spectrum of applications. Because of a lower critical electric field, drift regions in Si power transistors need to be much thicker and more lightly doped, which in turn increases the specific onresistance Ron,sp. To combat the drift resistance component for higher blocking voltages, superjunction MOSFETs for medium voltages and Si IGBTs for high voltages are used. Since IGBTs are bipolar transistors, they exhibit much higher switching energy losses than MOSFETs. The SiC MOSFET is an excellent candidate in the medium to high voltage range, which mainly targets the HEV market.</p><p><br></p><p>Due to their low channel mobility, SiC MOSFETs have not reached the theoretical limit below 1200 V where channel resistance is dominant. Planar DMOSFETs dominate the</p><p>commercial SiC market today because of higher yield and relatively simpler fabrication process, but trench MOSFETs can be made with a smaller cell area and thus lower Ron,sp. Due to lower cell-pitch and high integration density of trench-gate devices, they offer an opportunity to reduce the size and weight of HEV power control units by replacing IGBTs with MOSFETs. The single-trench UMOSFET was first reported in 1994 by CREE and the first oxide protected trench MOSFET in 1998 by Purdue. This structure inserts a grounded p-type region below the gate trench to protect the oxide in the blocking state. In 2012, Rohm Semiconductor reported a novel double-trench UMOSFET with separate gate and</p><p>field-protection trenches. In 2017, Infineon published their new trench UMOSFET, known as Cool-SiC, with high gate oxide reliability. In this work a deeply-scaled, fully-self-aligned trench MOSFET is fabricated and characterized. The innovative process described enables a record cell-pitch of 0.5 μm per channel, equivalent to a channel density 6Å~ higher than currently available commercial UMOSFETs.</p>

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This thesis presents an introduction to the design and simulation of a novel class of integrated photonic phased array switch elements. The main objective is to use nano-electromechanical (NEMS) based phase shifters of cascaded under-etched slot nanowires that are compact in size and require a small amount of power to operate them. The structure of the switch elements is organized such that it brings the phase shifting elements to the exterior sides of the photonic circuits. The transition slot couplers, used to interconnect the phase shifters, are designed to enable biasing one of the silicon beams of each phase shifter from an electrode located at the side of the phase shifter. The other silicon beam of each phase shifter is biased through the rest of the silicon structure of the switch element, which is taken as a ground. Phased array switch elements ranging from 2×2 up to 8×8 multiple-inputs/multiple-outputs (MIMO) are conveniently designed within reasonable footprints native to the current fabrication technologies. Chapter one presents the general layout of the various designs of the switch elements and demonstrates their novel features. This demonstration will show how waveguide disturbances in the interconnecting network from conventional switch elements can be avoided by adopting an innovative design. Some possible applications for the designed switch elements of different sizes and topologies are indicated throughout the chapter. Chapter two presents the design of the multimode interference (MMI) couplers used in the switch elements as splitters, combiners and waveguide crossovers. Simulation data and design methodologies for the multimode couplers of interest are detailed in this chapter. Chapter three presents the design and analysis of the NEMS-operated phase shifters. Both simulations and numerical analysis are utilized in the design of a 0º-180º capable NEMS-operated phase shifter. Additionally, the response of some of the designed photonic phased array switch elements is demonstrated in this chapter. An executive summary and conclusions sections are also included in the thesis.

This thesis presents an introduction to the design and simulation of a novel class of integrated photonic phased array switch elements. The main objective is to use nano-electromechanical (NEMS) based phase shifters of cascaded under-etched slot nanowires that are compact in size and require a small amount of power to operate them. The structure of the switch elements is organized such that it brings the phase shifting elements to the exterior sides of the photonic circuits. The transition slot couplers, used to interconnect the phase shifters, are designed to enable biasing one of the silicon beams of each phase shifter from an electrode located at the side of the phase shifter. The other silicon beam of each phase shifter is biased through the rest of the silicon structure of the switch element, which is taken as a ground. Phased array switch elements ranging from 2×2 up to 8×8 multiple-inputs/multiple-outputs (MIMO) are conveniently designed within reasonable footprints native to the current fabrication technologies. Chapter one presents the general layout of the various designs of the switch elements and demonstrates their novel features. This demonstration will show how waveguide disturbances in the interconnecting network from conventional switch elements can be avoided by adopting an innovative design. Some possible applications for the designed switch elements of different sizes and topologies are indicated throughout the chapter. Chapter two presents the design of the multimode interference (MMI) couplers used in the switch elements as splitters, combiners and waveguide crossovers. Simulation data and design methodologies for the multimode couplers of interest are detailed in this chapter. Chapter three presents the design and analysis of the NEMS-operated phase shifters. Both simulations and numerical analysis are utilized in the design of a 0º-180º capable NEMS-operated phase shifter. Additionally, the response of some of the designed photonic phased array switch elements is demonstrated in this chapter. An executive summary and conclusions sections are also included in the thesis.

Au cours de ces dernières années, les chercheurs ont démontré l’importance de l’accordabilité dans les systèmes de télécommunications fonctionnant pour des multiples bandes de fréquences, afin de réduire leur complexité et leur coût. Ce travail se focalise sur des filtres innovants accordables optiquement et propose ainsi une solution alternative aux méthodes plus classiques comme les MEMS ou les diodes. Cette thèse retrace la conception de trois résonateurs pouvant être de bons candidats à intégrer dans le système accordable optiquement développé au travers du manuscrit. Ces éléments sont conçus par le biais de différentes technologies comme : la technologie « Substrate Integrated Waveguide » combinée avec un effet dit métamatériau et la méthode de cavité chargée par un plot capacitif. Tous ces résonateurs ont été créés dans le but d’avoir des performances intéressantes pour trois critères : le facteur de qualité à vide (Q0), la plage d’accord (TR) et la taille. La dernière partie, quant à elle, se consacre au système d’accordabilité basé sur l’utilisation de capacité CMS et de switches RF contrôlés optiquement et fabriqués à l’aide de la technologie silicium CMOS. Plusieurs méthodes ont été utilisées afin d’améliorer les pertes d’insertion des switches RF et par conséquent les performances du système global, démontrant la faisabilité de ce concept innovant accordable optiquement. / Researchers have demonstrated over the last decade the importance of tunability to reduce the complexity and the cost of telecommunication systems operating at multiple frequency bands and standards. This work focuses on novel optically tunable filters for microwave applications and therefore proposes alternative solution to commonly used tuning methods such as MEMS or diodes. The thesis has investigated different resonators for having good candidates for the novel optically tunable system developed throughout this manuscript. Different technologies are used to design such components, namely: Substrate Integrated Waveguide (SIW) technology combined with metamaterial effect and cavity loading. All manufactured resonators are designed to be balanced between three features: the unloaded quality factor (Q0), the tuning range (TR) and the size. The last part deals with the tuning system based on SMT capacitance and optically controlled RF switches based on Si CMOS technology. Several methods have been used to improve the insertion loss of manufactured switches and therefore the performance of the whole system, demonstrating the feasibility of this novel optically based tunable concept.