<p>  </p> <p>Future artificial intelligence applications and data-intensive computations require the development of non-von Neumann architecture. Physical separation between a logic unit and a memory unit is one of the main bottlenecks of the traditional architecture, hindering unlocking the ultimate performance of electronic devices, such as power consumption and memory bandwidth limitation. However, to enable monolithic integration of high-performance logic and memory needs to resolve the fundamental thermal budget challenge of back-end-of-line (BEOL). In this regard, two-dimensional (2D) materials have drawn immense attention owing to their intrinsic performance, ultrathin bodies, and flexibility. The viability of low-temperature integration puts them in an advantageous position that rivals silicon technology.</p> <p><br></p> <p>Firstly, an entirely new phase change RRAM in MoTe2 can give rise to uniform switching by difference from a random filament formation of the conventional RRAM device. For a large memory array to function properly, it is crucial to have high nonlinearity of I-V characteristics for each device to suppress the sneak-path current. I experimentally demonstrate a proof-of-concept heterostructure consisting of 2D materials with the functionalities of the memory (MoTe2) and selector (WSe2). Next, a heterogeneously integrated 1-selector/1-resistor (1S1R) Ta2O5/MoTe2 RRAM cell was built for the first time employing 2D layered MoTe2 films, showing decent on/off-current ratios of ~730 and high nonlinearities of ∼5700. These values are considered state-of-the-art for built-in nonlinear RRAM devices to date. </p> <p><br></p> <p>Secondly, I demonstrate that a pure nitric oxide treatment at elevated temperatures provides a stable p-doping for monolayer WSe2. This approach allows achieving record high hole current densities of ~300 μA/μm and low contact resistances of ∼950 Ω·μm, while preserving the transistor on/off current ratio >2×106. This scalable pathway significantly improves the performance of p-type WSe2 transistors, opening new opportunities for p-type 2D materials to enable CMOS implementations for next-generation high-performance electronics. </p> <p><br></p> <p>Thirdly, I demonstrate all MoTe2 1-transistor/1-resistor (1T1R) memory cells, fabricated at low temperatures. The 1T1R cells can be switched with voltage ~ 1V, close to typical CMOS logic voltages. This demonstration underscores the potential of 2D materials and their monolithic integration toward the realization of future memory technologies. </p> <p><br></p> <p>Lastly, I adopt machine-learning (ML) algorithms to evaluate the design and process co-optimization from a vast number of 2D transistor device characteristics. This framework greatly optimizes the electrical performance of 2D transistors, serving as guidance for advancing future 2D electronics.</p>

This thesis is a study of the structural, electrical and magnetic properties of indium antimonide (InSb) nanowires (NWs), that were synthesized by a template-assisted ordered growth technique via electrochemical deposition. InSb was chosen for this study because of its intrinsic properties that make it a material of choice for applications in high channel mobility, infrared (IR) sensing, thermoelectrics, and magnetoresistive sensing martials. This work has four main components: (i) Growth in commercially available anodic aluminum oxide (AAO) template, where hole-dominated conduction was observed, following NW growth in a low pH electrolyte. The challenge in using these AAO templates was in covering the back surface of the pores with a metal film. Uncovered pores resulted in electrolyte leakage and non-reproducible results. (ii) Growth in flexible polycarbonate membranes, where the flexibility of the membranes resulted in polycrystalline or high defect density NW growth. (iii) Fabrication of an AAO template, where the barrier layer thinning technique was found to be efficient in removal of the think aluminum oxide barrier that exists at the interface between the template and the aluminum metal. This allows for direct growth of NWs into the template pores without the need for metal evaporation. (iv) Fabrication of a heterostructure comprising of an InSb layer sandwiched between two ferromagnetic contacts. Preliminary results show evidence of inverse spin-valve effect at the low temperature of 4K.

We developed and implemented a first-principles based theory of the Landauer ballistic conductance, to determine the transport properties of nanostructures and molecular-electronics devices. Our approach starts from a quantum-mechanical description of the electronic structure of the system under consideration, performed at the density-functional theory level and using finite-temperature molecular dynamics simulations to obtain an ensemble of the most likely microscopic configurations. The extended Bloch states are then converted into maximally-localized Wannier functions to allow us to construct the Green's function of the conductor, from which we obtain the density of states (confirming the reliability of our microscopic calculations) and the Landauer conductance. A first application is presented to the case of pristine and functionalized carbon nanotubes. / Singapore-MIT Alliance (SMA)

Low-dimensional semiconductors have been intensely explored as alternative active materials for future generation ultra-scaled smart electronics. However, significant roadblocks (e.g., poor carrier mobilities, instability, and vague potential in scaling-up) exist that prevent the realization of the current state-of-the-art low-dimensional materials’ potential for energy-efficient electronics. We first time developed hydrothermal method to solution-grown two-dimensional Te, which exhibits attractive attributes, e.g., high room-temperature mobility, large on-state current density, air-stability, and tunable material properties through a low-cost, scalable process, to tackle these challenges.

Les travaux de cette thèse portent sur le refroidissement descomposants électroniques de puissance par métal liquide. Les efforts se sontconcentrés plus particulièrement autour de deux fonctions : la pompeélectromagnétique servant à mettre le fluide en mouvement et le refroidisseur àminicanaux situé sous la source de dissipation.Le mémoire de thèse se structure en quatre chapitres équivalents. Dans lepremier, l’apport des métaux liquides pour le refroidissement des composantsactifs de puissance est démontré. Dans un deuxième temps, l’étude théorique etexpérimentale d’une pompe électromagnétique à conduction est effectuée. Lesystème de refroidissement est plus particulièrement abordé dans le troisièmechapitre. Enfin, des réflexions sur la mise en oeuvre des refroidisseurs à métauxliquides en électronique de puissance sont discutées dans la dernière partie.Grâce à elles, nous voyons que le champ d’application de ces travaux favorisel'émergence de solutions innovantes pour la gestion thermique des composantsélectronique de puissance. / The work presented in this Phd manuscript deals with cooling powerelectronics devices using an electrical conductive fluid. Two important functionshave been considered: the study and the realization of the electromagnetic pumpwhich circulated the fluid in the cooling loop. The second function was study andrealization of the cooler which evacuated the heat from the electronics device.This document has four chapters: introduction to power electronics coolingsystem with liquid metal, electromagnetic pump study, cooler study, and at lastreflections on realizing liquid metal cooler for power electronics devices. Theresults of this work concern a wide range of applications, especially towards newthermal management solutions of power electronics devices.

[ES] La presente tesis pone el foco en lo sonoro en un momento de cambios disruptivos operados por las tecnologías y su impacto en los globalizados sistemas sociales, culturales, políticos y científicos. La conceptualizada Industria 4.0 acelera a gran velocidad el proceso de digitalización y automatización de todas las esferas, activando nuevas relaciones humano-máquina, máquina-máquina; las ciudades modelos generalizados de vida, concentran gran parte de la actividad social y el volcado de los procesos tecnológicos, la hibridación físico-digital potenciada por la ubicuidad. Ya no se trata de la portabilidad del sonido ni de su reproducción, el cambio se produce por la colonización de nuestro tiempo y espacio, la conectividad infinita que media en todas nuestras transacciones, acontecimientos y la percepción de los lugares; las acciones de corporeización con dispositivos que se vuelven cuasitransparentes (Ihde, 2015), la conversión en cíborg al añadir nuestro cuerpo temporalmente para adaptarnos a un nuevo entorno (Case, 2018); el síndrome de atención parcial continuada (Stone, 2014) que nos mantiene en un estado de alerta, o el tiempo que, según Foucault, está gestionado como artefacto de la cultura y el resultado de las relaciones de poder. Desde el prisma del arte y su vertiente práctica, el estudio ofrece una lectura de la ciudad y los medios digitales a través de sus sonidos, un acercamiento que busca descifrar el carácter de un territorio, encontrar rastros de singularidad o de homogeneidad, la sintonía con los ambientes, y también el pensamiento de lo disruptivo. La investigación se expresa a través de propuestas sonoras y visuales, cartografías simbólicas y perceptivas, conjugadas con metodologías mestizas de estudio teórico-práctico interdisciplinario, en un proceso abierto y fluido de experimentación que se funda en la re-utilización o instanciación de medios, materiales y conceptos de manera que puedan arrojar ideas, lecturas no previstas o activar el pensamiento crítico y estético. / [EN] This thesis focuses on sound in times of disruptive changes operated by technologies and their impact on globalised social, cultural, political and scientific systems. The conceptualised Industry 4.0 accelerates the process of digitisation and automation at great speed and on all spheres, activating new human-machine, machine-machine relationships; cities, the generalised models of life, gather a large part of social activity and the dumping of technological processes, the physical-digital hybridisation promoted by ubiquity. It is no longer about the portability of sound or its reproduction, the change is takes place by the colonisation of our time and space, the infinite connectivity that mediates all our transactions, events and the perception of places; embodiment actions with devices that become quasi-transparent (Ihde, 2015), the transformation into cyborgs by temporarily adding our bodies to adapt to a new environment (Case, 2018); the syndrome of continued partial attention (Stone, 2014) that keeps us in a state of alert, or the time that, according to Foucault, is managed as a device for culture and the result of power relations. From the eyes of art and its practical side, the study offers a reading of the city and the digital media through its sounds, an approach that seeks to decipher the nature of a territory, find traces of singularity or homogeneity, the harmony with the environments, and also the thought of the disruptive. The research is expressed through sound and visual proposals, symbolic and perceptual cartographies, blended with hybrid methodologies of interdisciplinary theoretical-practical study, in an open and fluid experimentation process that is based on the re-use or instantiation of media, materials and concepts so that they can shed ideas, unforeseen readings or activate critical and aesthetic thinking. / [CA] Aquesta tesi posa el focus en allò sonor en un moment de canvis disruptius operats per les tecnologies i el seu impacte en els globalitzats sistemes socials, culturals, polítics i científics. La conceptualitzada Indústria 4.0 accelera a gran velocitat el procés de digitalització i automatització de totes les esferes, i activa noves relacions humà-màquina, màquina-màquina. Les ciutats, models generalitzats de vida, concentren una gran part de l'activitat social i l'abocament de dades dels processos tecnològics, la hibridació físicodigital potenciada per la ubiqüitat. No es tracta ja de la portabilitat del so ni de la seua reproducció, el canvi es produeix per la colonització del nostre temps i espai, la connectivitat infinita que media en totes les nostres transaccions, esdeveniments i la percepció dels llocs; les accions de corporeïtzació amb dispositius que es tornen quasitransparents (Ihde, 2015), la conversió en cíborg en afegir el nostre cos temporalment per a adaptar-nos a un nou entorn (Case, 2018), la síndrome d'atenció parcial continuada (Stone, 2014), que ens manté en un estat d'alerta, o el temps que, segons Foucault, és gestionat com a artefacte de la cultura i el resultat de les relacions de poder. Des del prisma de l'art i el seu vessant pràctic, l'estudi ofereix una lectura de la ciutat i els mitjans digitals a través dels seus sons, un acostament que busca desxifrar el caràcter d'un territori, trobar rastres de singularitat o d'homogeneïtat, la sintonia amb els ambients, i també el pensament del disruptiu. La investigació s'expressa a través de propostes sonores i visuals, cartografies simbòliques i perceptives, conjugades amb metodologies mestisses d'estudi teòric i pràctic interdisciplinari, en un procés obert i fluid d'experimentació que es funda en la re-utilització o instanciació de mitjans, materials i conceptes de manera que puguen llançar idees, lectures no previstes o activar el pensament crític i estètic. / A la Universitat Politècnica de València por la beca FPI y la estancia de investigación concedidas para dar cobertura económica a este trabajo y ayudar a mi formación. / Rodríguez López, R. (2021). Prácticas experimentales e indagación sobre sonido, territorio y tecnologías contemporáneas: Cartografías, soportes de escucha y sonidos disruptivos [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/162974

L'objectif du projet VELSIC a été de démontrer la faisabilité de jonctions p+/n- profondes dans le semiconducteur 4H-SiC, de haute qualité électrique, comprenant une zone p++ réalisée par un procédé original d'épitaxie localisée à basse température (1100 – 1200°C), en configuration VLS (Vapeur - Liquide - Solide). Cette technique innovante de dopage par épitaxie utilise le substrat de SiC mono cristallin comme un germe de croissance sur lequel un empilement enterré de Al - Si est porté à fusion pour constituer un bain liquide, lequel est alimenté en carbone par la phase gazeuse. Cette méthode se positionne comme une alternative avantageuse à l'implantation ionique, actuellement utilisée par tous les fabricants de composants en SiC, mais qui présente des limitations problématiques encore non résolues à ce jour. Les travaux de thèse ont exploré toutes les facettes du processus complet de fabrication de diodes de test, avec une attention particulière portée sur l'optimisation de la gravure de cuvettes dans le substrat SiC. Le cœur des travaux a été concentré sur l'optimisation de l'épitaxie VLS localisée. L'étude a confirmé la nécessité de limiter la vitesse de croissance vers 1 µm/h pour conserver une bonne cristallinité du matériau épitaxié. Elle a également mis en évidence l'action directe du champ électromagnétique radiofréquence sur la phase liquide, conduisant à une très forte influence du diamètre des cuvettes gravées sur l'épaisseur du SiC déposé. Un remplissage quasiment complet des cuvettes de 1 µm de profondeur à très fort dopage p++ a été démontré. À partir des couches VLS optimisées, des démonstrateurs de types diodes p+/n- ont été fabriqués. Sur les meilleurs échantillons, sans passivation ni protection périphérique, des tensions de seuil en régime direct (entre 2,5 et 3 V) ont, pour la première fois, été mesurées, sans recourir à un recuit haute température après épitaxie. Elles correspondent aux valeurs attendues pour une vraie jonction p-n sur 4H-SiC. Des densités de courant de plusieurs kA/cm2 ont également pu être injectées pour des tensions situées autour de 5 - 6 V. En régime de polarisation inverse, aucun claquage n'est observé jusqu'à 400 V et les densités de courant de fuite à faible champ électrique dans la gamme 10-100 nA/cm2 ont été mesurées. Toutes ces avancées si situent au niveau de l'état de l'art pour des composants SiC aussi simples, toutes techniques de dopage confondues / The objective of the VELSIC project has been to demonstrate the feasibility of 1 µm deep p+/n- junctions with high electrical quality in 4H-SiC semiconductor, in which the p++ zone is implemented by an original low-temperature localized epitaxy process ( 1100 - 1200 °C ), performed in the VLS (Vapor - Liquid - Solid) configuration. This innovative epitaxy doping technique uses the monocrystalline SiC substrate as a crystal growth seed. On the substrate (0001-Si) surface, buried patterns of Al - Si stack are fused to form liquid islands which are fed with carbon by C3H8 in the gas phase. This method is investigated as a possible higher performance alternative to the ion implantation process, currently used by all manufacturers of SiC devices, but which still experiences problematic limitations that are yet unresolved to date. Although the main focus of the study has been set on the optimization of localized VLS epitaxy, our works have explored and optimized all the facets of the complete process of test diodes, from the etching of patterns in the SiC substrate up to the electrical I - V characterization of true pn diodes with ohmic contacts on both sides.Our results have confirmed the need to limit the growth rate down to 1 µm/h to maintain good crystallinity of the epitaxial material. It has also highlighted the direct action of the radiofrequency electromagnetic field on the liquid phase, leading to a very strong influence of the diameter of the etched patterns on the thickness of the deposited SiC. A nearly complete filling of the 1 µm deep trenches with very high p++ doping has been demonstrated. Using optimized VLS growth parameters, p+/n- diode demonstrators have been processed and tested. On the best samples, without passivation or peripheral protection, high direct-current threshold voltages, between 2.5 and 3 V, were measured for the first time without any high-temperature annealing after epitaxy. These threshold voltage values correspond to the expected values for a true p-n junction on 4H-SiC. Current densities of several kA/cm2 have also been injected at voltages around 5 - 6 V. Under reverse bias conditions, no breakdown is observed up to 400 V and low leakage current densities at low electric field, in the range 10 - 100 nA/cm2, have been measured. All these advances align with or exceed state-of-the-art results for such simple SiC devices, obtained using any doping technique