abstract: Lateral programmable metallization cells (PMC) utilize the properties of electrodeposits grown over a solid electrolyte channel. Such devices have an active anode and an inert cathode separated by a long electrodeposit channel in a coplanar arrangement. The ability to transport large amount of metallic mass across the channel makes these devices attractive for various More-Than-Moore applications. Existing literature lacks a comprehensive study of electrodeposit growth kinetics in lateral PMCs. Moreover, the morphology of electrodeposit growth in larger, planar devices is also not understood. Despite the variety of applications, lateral PMCs are not embraced by the semiconductor industry due to incompatible materials and high operating voltages needed for such devices. In this work, a numerical model based on the basic processes in PMCs – cation drift and redox reactions – is proposed, and the effect of various materials parameters on the electrodeposit growth kinetics is reported. The morphology of the electrodeposit growth and kinetics of the electrodeposition process are also studied in devices based on Ag-Ge30Se70 materials system. It was observed that the electrodeposition process mainly consists of two regimes of growth – cation drift limited regime and mixed regime. The electrodeposition starts in cation drift limited regime at low electric fields and transitions into mixed regime as the field increases. The onset of mixed regime can be controlled by applied voltage which also affects the morphology of electrodeposit growth. The numerical model was then used to successfully predict the device kinetics and onset of mixed regime. The problem of materials incompatibility with semiconductor manufacturing was solved by proposing a novel device structure. A bilayer structure using semiconductor foundry friendly materials was suggested as a candidate for solid electrolyte. The bilayer structure consists of a low resistivity oxide shunt layer on top of a high resistivity ion carrying oxide layer. Devices using Cu2O as the low resistivity shunt on top of Cu doped WO3 oxide were fabricated. The bilayer devices provided orders of magnitude improvement in device performance in the context of operating voltage and switching time. Electrical and materials characterization revealed the structure of bilayers and the mechanism of electrodeposition in these devices. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2020

This work examines the selective deposition of two different metals on the same DNA origami template for nanofabrication. DNA, with adjustable size and shape serves as a suitable template for fabricating metal junctions in the nanometer domain via bottom-up assembly. Bottom-up assembly utilizes the recognition capability of molecules like DNA to self-assemble and form structures. In this regard, DNA origami provides a useful means for forming nanostructures by folding single-stranded DNA into different two and three dimensional shapes. Selective deposition of metal on specific locations of a DNA template is essential for making DNA-templated electronic circuits.Site-specific metallization of DNA origami templates was recently demonstrated, for a single metal at molecularly designated sites. This study addresses the next important step of depositing multiple metals on the same template. Specifically, it is an experimental study to demonstrate the gold-copper metal junction on a DNA origami template, and to understand the challenges associated with junction fabrication. DNA-templated circuit fabrication depends on the ability to deposit multiple components on a DNA template. To achieve this, a section of the DNA template was seeded with Au nanoparticles and electrolessly plated with Au. This Au plated section of the template was then masked with an organic layer to protect it from additional deposition. The remaining section of the same template was subsequently seeded with Pd and plated with copper to form the desired metal junction. This work is the first of its kind to demonstrate metal junctions on a DNA origami template. Metallized origami templates were characterized with the help of SEM imaging and EDX composition data to confirm the presence of the two different metals on the same template. In addition, a chemical “mask” was also used successfully at nanometer resolution to protect previously metallized sites (gold plated) to prevent further metal deposition. The results obtained represent important progress toward the realization of DNA-templated components for nano-circuit fabrication. The work also provides the basis for the next step to make metal-semiconductor junctions on a DNA template.

Building metal nanomaterials with tailored electrical properties is in high demand for electronic device fabrication. However, scalable and inexpensive fabrication of such metallic structures with nanometer precision remains a challenge. DNA origami is a versatile and robust self-assembly method which allows fabrication of arbitrary structures at the nanoscale. In this thesis, DNA origami templated metal nanostructure fabrication method is introduced. Continuous metal nanostructures with controlled geometry as well as the selective deposition of multi-nanomaterials (metals and semiconductors) at specific sites on origami templates play an im-portant role in the fabrication of DNA based nanoelectronics system. A mold DNA origami with quadratic cross-section was constructed and used as template for the gold nanoparticles metal growth. Each individual mold element acted as a lego-brick in this modular mold system. (1) Linear metallic nanostructures with controlled length and programmable patterns were fabricat-ed at superior yields by systematically investigating the interface of each mold element. (2) A versatile fabrication modular mold platform for metallic nanostructures with complex shapes was further developed by integrating particular molds with different diameters, additional dock-ing sites, and junctions. Caged metal nanostructures, constrained gold growth and branched structures with extensions in two dimensions were successfully realized. (3) Micrometer long, homogeneous and continuous gold nanowires were obtained with exceeding quality. Using elec-tron-beam lithography and low-temperature conductance measurements, ohmic behavior of such nanowires were observed, confirming metallic conductive property. (4) A method for the synthesis and DNA functionalization of semiconducting nanorods was established. Metal-semiconductor heterostructures were fabricated based on the modular mold system. Semicon-ducting nanorods, as well as gold nanoparticles, were placed at defined positions on the DNA modular platform and a direct metal-semiconductor interface was achieved after the electroless metal deposition. (5) An improved and optimized metallization of DNA origami templated gold nanowires were further developed to increase the conductivity performance. Various reaction parameters were investigated and the obtained gold nanowires with a reduced number of AuNPs achieved an anisotropic growth. This developed DNA origami template mold modular platform addresses the size, pattern, and geometry controls over the metallic nanostructures. For the ap-plication prospect, the conductivity of such metallic nanostructures and controlled placement of different nanomaterials enable an important step towards the nanodevices and systems fabrica-tion based on DNA. / Der Aufbau metallischer Nanomaterialien mit angepassten elektrischen Eigenschaften ist für die Verwendung in elektronischen Bauteilen von großer Bedeutung. Dabei ist die skalierbare und günstige Herstellung metallischer Strukturen im Nanometerbereich weiterhin eine Herausforderung. Die DNA Origami Technik bietet hier eine vielseitig einsetzbare und stabile Methode zur Selbstassemblierung, welche die Herstellung beliebiger nanoskalierter Strukturen ermöglicht. In dieser Arbeit wird ein neuer Ansatz zur Herstellung metallischer Nanostrukturen mit Hilfe von DNA Origami Templaten vorgestellt. Kontinuierliche Metallnanostrukturen mit einer definierten Geometrie, sowie die selektive Anbindung verschiedener Nanomaterialien (Metalle und Halbleiter) an spezifischen Anbindungsstellen des Origamitemplates spielen eine wichtige Rolle bei der Herstellung DNA basierter nanoelektrischer Systeme. Ein DNA Origami Mold mit einem quadratischen Querschnitt wurde als Templat für die Metallisierung von Goldnanopartikeln verwendet. Das legostein-artige Design der einzelnen Origami Molds ermöglicht die Assemblierung in einem modularen System. (1) Lineare metallische Nanostrukturen mit kontrollierter Länge und programmierbarem Muster wurden mit hohen Ausbeuten assembliert, indem das Interface der einzelnen Origamistrukturen systematisch untersucht wurde. (2) Weiterhin wurde eine vielseitige, sowie modulare Plattform für metallische Nanostrukturen mit komplexen Formen entwickelt. Dabei wurden spezielle Origamistrukturen mit unterschiedlichem Durchmesser, sowie zusätzlichen Anbindungsstellen und Verzweigungen integriert. Die erfolgreiche Metallisierung linearer und verzweigter Nanostrukturen in zwei Dimensionen wurde durch ein restriktives Goldwachstum im Inneren der Origamistrukturen realisiert. (3) Homogene und kontinuierliche Goldnanodrähte mit Mikrometerlänge und außerordentlicher Qualität wurden fabriziert. Mit Hilfe von Elektronenstrahllithographie wurde die Leitfähigkeit der Strukturen im Niedrigtemperaturbereich untersucht, wobei ein ohmsches Ladungstransportverhalten der Nanodrähte nachgewiesen werden konnte, welches die metallische Leitfähigkeit der Strukturen bestätigte. (4) Eine Methode zur Synthese und DNA Funktionalisierung von Halbleiternanostäbchen wurde eingeführt. Zudem konnten Metall-Halbleiterheterostrukturen hergestellt werden, basierend auf dem entworfenen modularen Origamisystem. Halbleiternanostäbchen und Goldnanopartikel wurden an definierten Positionen der DNA Origami platziert. Durch eine anschließende Metallisierung konnte ein direktes Metall-Halbleiterinterface hergestellt werden. (5) Eine verbesserte und optimierte Metallisierung der DNA Origami basierten Goldnanodrähte zur Erhöhung der Leitfähigkeit wurde entwickelt. Dazu wurden verschiedene Reaktionsparameter optimiert, so dass ein anisotropes Wachstum mit einer reduzierten Anzahl von Goldnanopartikel ermöglicht werden konnte. Die, in dieser Arbeit entwickelte DNA Origami Plattform ermöglicht die Kontrolle über Größe, Struktur und Geometrie metallischer Nanostrukturen. Die ohmsche Leitfähigkeit dieser Nanostrukturen und die zusätzliche Assemblierung verschiedener Nanomaterialien stellen dabei einen wichtigen Schritt für eine potentielle Verwendung in elektrischen Nanogeräten dar.

<p>In this research, we have studied the interaction between femtosecond laser and dielectric material, especially borosilicate glass, and its applications. Using laser direct writing (LDW), optical fiber sensors and selective metallization of glass surface were explored. For ultrafine selective metallization, supersonic spray deposition system was introduced combining to femtosecond laser direct writing.</p>

Silicon carbide is a promising semiconductor material for high voltage, high frequency and high temperature devices due to its wide bandgap, high breakdown electric field strength, highly saturated drift velocity of electrons and outstanding thermal conductivity. With the aim of overcoming some challenges in metallization and doping during the fabrication of silicon carbide devices, a novel laser-based process is provided to direct metallize the surface of silicon carbide without metal deposition and dope in silicon carbide without high temperature annealing, as an alternative to the conventional ion implantation, and find applications of this laser direct write metallization and doping technique on the fabrication of diodes, endotaxial layer and embedded optical structures on silicon carbide wafers. Mathematical models have been presented for the temperature distributions in the wafer during laser irradiation to optimize laser process parameters and understand the doping and metallization mechanisms in laser irradiation process. Laser irradiation of silicon carbide in a dopant-containing ambient allows to simultaneously heating the silicon carbide surface without melting and incorporating dopant atoms into the silicon carbide lattice. The process that dopant atoms diffuse into the bulk silicon carbide by laser-induced solid phase diffusion (LISPD) can be explained by considering the laser enhanced substitutional and interstitial diffusion mechanisms. Nitrogen and Trimethyaluminum (TMA) are used as dopants to produce n-type and p-type doped silicon carbide, respectively. Two laser doping methods, i.e., internal heating doping and surface heating doping are presented in this dissertation. Deep (800 nm doped junction for internal heating doping) and shallow (200 nm and 450 nm doped junction for surface heating doping) can be fabricated by different doping methods. Two distinct diffusion regions, near-surface and far-surface regions, were identified in the dopant concentration profiles, indicating different diffusion mechanisms in these two regions. The effective diffusion coefficients of nitrogen and aluminum were determined for both regions by fitting the diffusion equation to the measured concentration profiles. The calculated diffusivities are at least 6 orders of magnitude higher than the typical values for nitrogen and aluminum, which indicate that laser doping process enhances the diffusion of dopants in silicon carbide significantly. No amorphization was observed in laser-doped samples eliminating the need for high temperature annealing. Laser direct metallization can be realized on the surface of silicon carbide by generating metal-like conductive phases due to the decomposition of silicon carbide. The ohmic property of the laser direct metallized electrodes can be dramatically improved by fabricating such electrodes on laser heavily doped SiC substrate. This laser-induced solid phase diffusion technique has been utilized to fabricate endolayers in n-type 6H-SiC substrates by carbon incorporation. X-ray energy dispersive spectroscopic analysis shows that the thickness of endolayer is about 100 nm. High resolution transmission electron microscopic images indicate that the laser endotaxy process maintains the crystalline integrity of the substrate without any amorphization. Rutherford backscattering studies also show no amorphization and evident lattice disorder occur during this laser solid phase diffusion process. The resistivity of the endolayer formed in a 1.55 omega•cm silicon carbide wafer segment was found to be 1.1E5 omega•cm which is sufficient for device fabrication and isolation. Annealing at 1000 oC for 10 min to remove hydrogen resulted in a resistivity of 9.4E4 omega•cm. Prototype silicon carbide PIN diodes have been fabricated by doping the endolayer and parent silicon carbide epilayer with aluminum using this laser-induced solid phase diffusion technique to create p-regions on the top surfaces of the substrates. Laser direct metallized contacts were also fabricated on selected PIN diodes to show the effectiveness of these contacts. The results show that the PIN diode fabricated on a 30 nm thick endolayer can block 18 V, and the breakdown voltages and the forward voltages drop at 100 A/cm2 of the diodes fabricated on 4H-SiC with homoepilayer are 420 ~ 500 V and 12.5 ~ 20 V, respectively. The laser direct metallization and doping technique can also be used to synthesize embedded optical structures, which can increase 40% reflectivity compared to the parent wafer, showing potential for the creation of optical, electro-optical, opto-electrical, sensor devices and other integrated structures that are stable in high temperature, high-pressure, corrosive environments and deep space applications.

No description available.

No description available.

Cette thèse a pour but d’étudier le principe d’un multiplexeur de sortie accordable pour la charge utile d’un satellite de télécommunication. La première étape consiste à analyser les principales topologies de multiplexeur de sortie utilisables et les comparer pour en retirer le meilleur candidat pour cette application. Par la suite, diverses études ont été menées sur des composants passifs imprimés en 3D plastique et métallisés de diverses manières, en cherchant à comprendre comment améliorer au mieux les résultats de ces prototypes. La dernière partie de ce manuscrit détaille la conception d’un multiplexeur à deux canaux pouvant être utilisé sur trois états différents en large bande à 19 GHz. Ces états sont créés par des bandes passantes relatives variant de 1,6 à 4,8 % et une réalisation de deux maquettes sert de preuves de concept et de performance (une en plastique métallisé et la seconde en aluminium usiné). / This thesis is about study of tunable output multiplexer principle for telecommunication satellite payload. The first step is analysis of the main topologies of output multiplexers and to compare them to conclude with the best candidate. Then, several studies were conducted on 3D plastic printed passive components with specific metallizations, searching how to improve results in term of losses and precision. Last part detailed two channels multiplexer design which can be used on three different states of relative bandwidth from 1.6 to 4.8 % at 19 GHz, and realization of two concept proof prototypes (one in metallized 3D printed plastic and another one in machined aluminum).

Grâce à la métallisation de leur surface, des pièces en polymères peuvent substituer certains composants métalliques dans les industries de l'aérospatiale et du transport. Les polymères ont des masses volumiques plus faibles que les métaux et une réactivité chimique limitée, ce qui en fait des candidats idéaux pour les applications spatiales. En combinant techniques expérimentales et simulations numériques, nous avons étudié les mécanismes fondamentaux de la métallisation de surface d'un polymère poly-époxy (DGEBA / EDA). L'objectif de notre étude était de développer un modèle non empirique prenant en compte les mécanismes régissant la nucléation et la croissance des films minces métalliques. Notre groupe a une longue expérience des dépôts chimiques en phase vapeur, CVD. Mais cette technique n'a pas été choisie pour la métallisation de nos surfaces de polymères car les températures requises dans le réacteur étaient trop élevées. Comme alternative, nous avons effectué une évaporation sous ultravide de Cu à température ambiante, conduisant à une diffusion des atomes en phase gazeuse sans énergie cinétique. Les processus d'adsorption et de diffusion sont donc plus proches des conditions thermodynamiques associées aux calculs. Un protocole expérimental a été mis en place afin de créer une surface polymère chimiquement homogène présentant une faible rugosité. Le polymère obtenu a été caractérisé (i) par spectroscopie infrarouge à transformée de Fourier, pour déterminer le taux de polymérisation (supérieur à 90%), (ii) par calorimétrie différentielle à balayage pour obtenir la température de transition vitreuse (Tg) ( 118,1 °C), (iii) par microscopie à force atomique (AFM) pour estimer la rugosité de la surface (Ra ˜ 1 nm), et (iv) par spectroscopie de photoélectrons X (XPS) pour caractériser les liaisons chimiques de surface. La surface de polymère a ensuite été métallisée. Grâce à des analyses AFM, l'épaisseur du film mince a été estimée à 6 nm. Nous avons ensuite utilisé l'XPS pour caractériser les liaisons interfaciales Cu / Poly-époxy. Nous avons déduit de l'interprétation des spectres XPS que le Cu est adsorbé préférentiellement sur un atome d'oxygène spécifique du polymère. Pour identifier clairement ces sites d'adsorption de Cu, nous avons ensuite simulé les spectres XPS du polymère non revêtu, par des calculs quantiques, en utilisant un modèle moléculaire (dimère : 1 molécule de DGEBA liée à 1 molécule d'EDA). Les méthodes Hartree-Fock (HF) et de la théorie de la fonctionnelle de la densité (DFT) nous ont permis de simuler des spectres XPS pour la surface nue, en prenant en compte les effets d'état final et initial. Grâce à ces résultats, nous avons pu décomposer le spectre expérimental en 8 contributions, ce qui conduit à des résultats beaucoup plus précis que les résultats habituels obtenus par l'utilisation exclusive des expériences et de la littérature. Nous avons ensuite effectué des simulations de dynamique moléculaire classique (MD) pour passer d'un modèle moléculaire (dimère) à un modèle de polymère amorphe. / Metallization of polymer surfaces can lead to the substitution of metallic components. Polymers have lower densities and limited chemical reactivity, making them ideal candidates for the space applications. Through experiments and calculations, we studied the fundamental mechanisms of surface metallization of a poly-epoxy polymer (DGEBA/EDA). The objective of our study was to develop a non-empirical model that could take into account the mechanisms governing the nucleation and growth of thin metal films. Our group has a long experience in chemical vapor deposition, CVD, and metallization of polymer composites. But we did not applied CVD at first because of the high temperatures required in the reactor. We alternatively used ultrahigh vacuum evaporation of Cu at ambient temperature. Therefore, we make sure that atoms diffuse in the gas phase without kinetic energy. Adsorption and diffusion processes are thus closer to thermodynamic conditions that prevails in calculations. An experimental protocol was refined in order to create a chemically homogeneous polymer surface with a low roughness (Ra<1nm). The bulk and the surface of the pristine polymer were characterized (i) by Fourier Transform Infrared Spectroscopy, to determine the polymerization rate (above 90%), (ii) by differential scanning calorimetry in order to obtain the glass transition temperature (Tg) (118.1 °C), (iii) by atomic force microscopy (AFM) to calculate surface roughness (Ra ˜ 1 nm), and (iv) by X-ray photoelectron spectroscopy (XPS) to characterize surface chemical bonding. The surface was then metallized. Through AFM, the thickness of the thin film was estimated at 6 nm. We then used XPS to characterize the Cu/Poly-epoxy interfacial bonding. We deduced that Cu adsorbed preferentially on a specific oxygen atom of the polymer. To clearly identify this Cu adsorption site, we further simulated the XPS spectra of our clean or metallized polymer by quantum calculations, using a dimer model (1 molecule of DGEBA connected to 1 molecule of EDA). In the Hartree-Fock (HF) and Density Functional Theory (DFT) framework, we first simulated the XPS spectra for the pristine surface taking into account initial and final state effects. Thanks to these results, we were able to analyze the experimental spectrum with 8 contributions, leading to much more accurate results than the usual results obtained by the exclusive use of experiments and literature. We then performed classical Molecular Dynamics (MD) simulations to move from a dimer model to an amorphous polymer model. We used the general Amber force field (GAFF) and we developed a code to mimic the reticulation of monomers molecules. We started from a stoichiometric mixture of DGEBA and EDA molecules. When equilibration was reached, structural properties at 700K (e.g. distribution of bonds) were extracted from the results of the NPT simulations. From this melt of monomers, the homemade reticulation code identified and connected reactive atoms (at a pre-defined inter-atomic distance < 3Å). After each step of polymerization, the system was equilibrated at 700K (NPT simulations). After multiple reticulation/MD cycles we could achieve a polymerization rate of 93% and the Radial Distribution Function (RDF), the density and the glass transition temperature Tg were calculated. The value of the computed density was 1.115 at 300K and the calculated Tg (115.5 °C) was in good agreement with the experimental Tg of 118.1 °C, validating our numerical approach to develop a model for poly-epoxies.

Adsorption of monolayers and multilayers of metal-free and metal phthalocyanines molecules on metal surfaces has been investigated using complementary microscopic and synchrotron-based spectroscopic techniques. It was observed by STM measurements that at monolayer coverage the adsorption direction of the metal-free phthalocyanine molecules with respect to the gold surface vary as a function of temperature, i.e. at room temperature (RT) and low temperature (LT). It was explained by the difference in strength of intermolecular and adsorbate-substrate interactions at room and low temperatures. Nature of the interaction between adsorbed species and the surfaces as a function of coverage has been further characterized by XPS measurements. Binding energy shifts as a function of coverage have been attributed to initial- and final-state effects, the latter being due to different core-hole screening for the different molecular coverage. The alignment of molecular films at both monolayer and multilayer coverages, which has been determined by XAS measurements in several cases, is also dependent upon the relative strength of molecule-molecule versus molecule-substrate interaction. Parallel alignment of the molecular film with respect to the surface is the result of significant interaction between the adsorbate and the substrate, whilst standing geometry of the molecular film is due to more significant intermolecular interactions. DFT simulations have provided further information on the nature of the adsorbate-substrate interaction as well as contribution of different molecular orbitals in XPS and XAS spectra. Moreover, investigation of alkali interaction with the phthalocyanine films revealed a significant modification in their geometric and electronic structures due to charge transfer from the alkali metal to the molecular film. However, no sign of metallization of the molecules has been observed by spectroscopic and microscopic studies.