In an era in which the amount of produced and stored data continues to exponentially grow, standard memory concepts start showing size, power consumption and costs limitation which make the search for alternative device concepts essential. Within a context where new technologies such as DRAM, magnetic RAM, resistive RAM, phase change memories and eFlash are explored and optimized, ferroelectric memory devices like FeRAM seem to showcase a whole range of properties which could satisfy market needs, offering the possibility of creating a non-volatile RAM. In fact, hafnia and zirconia-based ferroelectric materials opened up a new scenario in the memory technology scene, overcoming the dimension scaling limitations and the integration difficulties presented by their predecessors perovskite ferroelectrics. In particular, HfₓZr₁₋ₓO₂ stands out because of high processing flexibility and ease of integration in the standard semiconductor industry process flows for CMOS fabrication. Nonetheless, further understanding is necessary in order tocorrelate device performance and reliability to the establishment of ferroelectricity itself. The aim of this work is to investigate how the composition of the ferroelectric oxide, together with the one of the electrode materials influence the behavior of a ferroelectric RAM. With this goal, different process parameters and reliability properties are considered and an analysis of the polarization reversal is performed. Starting from undoped hafnia and zirconia and subsequently examining their intermixed system, it is shown how surface/volume energy contributions, mechanical stress and oxygen-related defects all concur in the formation of the ferroelectric phase. Based on the process optimization of an HfₓZr₁₋ₓO₂-based capacitor performed within these pages, a 64 kbit 1T1C FeRAM array is demonstrated by Sony Semiconductor Solutions Corporation which shows write voltage and latency as low as 2.0 V and 16 ns, respectively. Outstanding retention and endurance performances are also predicted, which make the addressed device an extremely strong competitor in the semiconductor scene.

Reconfigurable transistors merge unipolar p- and n-type characteristics of field-effect transistors into a single programmable device. Combinational circuits have shown benefits in area and power consumption by fine-grain reconfiguration of complete logic blocks at runtime. To complement this volatile programming technology, a proof of concept for individually addressable reconfigurable nonvolatile transistors is presented. A charge-trapping stack is incorporated, and four distinct and stable states in a single device are demonstrated.

We provide a mathematical formulation of flight-specific delay cost functions that enables a detailed tactical consideration of how a given flight delay will interact with all downstream constraints in the respective aircraft rotation. These functions are reformulated into stochastic delay cost functions to respect conditional probabilities and increasing uncertainty related to more distant operational constraints. Conditional probabilities are learned from historical operations data, such that typical delay propagation patterns can support the flight prioritization process as a part of tactical airline schedule recovery. A case study compares the impact of deterministic and stochastic cost functions on optimal recovery decisions during an airport constraint. We find that deterministic functions systematically overestimate potential disruption costs as well as optimal schedule recovery costs in high delay situations. Thus, an optimisation based on stochastic costs outperforms the deterministic approach by up to 15%, as it reveals ‘hidden’ downstream recovery potentials. This results in different slot allocations and in fewer passengers missing their connections.

This work is inspired by the peculiar behavior of the natural systems, namely the ability to produce self-sustained oscillations in the level of tens of Hertz in constant ambient conditions. This feature is one of the key signatures prescribed to living organisms. The firing rate of neuronal cells, a pulsating heart, or the beating of cilia and flagella are among many biological examples that possess amazing functionalities and unprecedented intelligence solely relying on bio-electro-chemical processes. Exploring shapeable polymeric technologies, new self-oscillating artificial microsystems were developed within this thesis. These microsystems rely on the novel nonlinear architecture that exhibits a negative differential resistance (NDR) within the parametric response that enables periodic oscillations. These systems are made of polymers and metals and were microfabricated in a planar fashion. The electrochemically deposited ionic electroactive polymers act as actuators of the system. Upon the self-assembly process, due to the interlayer strains, the planar device transforms into a three-dimensional soft nonlinear system that is able to perform self-sustained relaxation oscillations when subjected to a constant electric field while consuming extremely low powers (as low as several microwatts). The parameters of these systems were tuned for a high oscillation amplitude and frequency. This electro-mechanical parametric relaxation oscillator (EMPRO) can generate a rhythmic motion at stroke frequencies that are biologically relevant reaching up to ~95 Hz. The EMPRO oscillations at high frequencies generate a flow in the surrounding liquid, which was observed in the form of vortices around the micro actuators. This flow was further studied in ex-vivo conditions by measuring Doppler shifts of ultrasound waves. The EMPRO was made autonomous by integrating an electrochemical voltaic cell. Four different electrochemical batteries were tested to match the power consumption of the EMPRO system and electrochemical compatibility of the surrounding media. An Ag-Mg primary cell was then integrated with the EMPRO for autonomous operation without the need for external power sources, cables or controllers. This biomimicking self-powered self-sustaining oscillating microsystem is envisioned to be useful in novel application scenarios operating at low Reynolds numbers in biologically relevant conditions. Furthermore, as the system is electromechanical in nature, it could be integrated with electronic components such as sensors and communication devices in the next generation of autonomous microsystems.:  Table of contents Acronyms 7 1 Introduction 8 1.1 Motivation 9 1.2 Objectives 9 1.3 Thesis organization 10 2 Background 12 2.1 A brief review on nonlinear self-oscillation 12 2.2 Self-oscillating biological systems 13 2.3 Stimuli responsive materials 15 2.3.1 Electroactive polymers in electrochemical cells 16 2.3.2 Sources of electrical field for electroactive polymers 24 2.4 Self-oscillating synthetic systems 27 2.5 Movement in low Reynolds number regime 33 3 Materials and methods 38 3.1 Deposition methods 38 3.1.1 Photolithography 38 3.1.2 Plasma sputtering 41 3.1.3 Atomic layer deposition 42 3.1.4 Electrochemical polymerization 44 3.2 Shapeable polymeric platform technology 46 3.2.1 Sacrificial layer 46 3.2.2 Hydrogel swelling layer 47 3.2.3 Polyimide reinforcing layer 48 3.3 Characterization methods 49 3.3.1 Profilometry 49 3.3.2 Scanning electron and focused ion beam microscopy 50 3.3.3 Cyclic Voltammetry 52 3.3.4 Ultrasound and Doppler shift measurements 53 4 Electromechanical Parametric Relaxation Oscillators (EMPROs) 56 4.1 Relaxation oscillation in EMPROs 56 4.2 Theory of EMPRO relaxation oscillations 61 4.3 Realization of EMPROs 67 4.3.1 Design parameters of EMPROs 67 4.3.2 EMPRO on-chip battery integration 71 4.4 Fabrication of autonomous EMPROs 76 5 EMPRO performances 84 5.1 Externally biased EMPROs 84 5.2 Autonomous EMPROs 95 6 Conclusions and outlook 98 6.1 Outlook 99 Bibliography i List of Figures and Tables xi Versicherung xiii Acknowledgements xiv Scientific publications and contributions xvi Theses xvii Curriculum Vitae xix

Image guidance using in-beam real-time magnetic resonance (MR) imaging is expected to improve the targeting accuracy of proton therapy for moving tumors, by reducing treatment margins, detecting interfractional and intrafractional anatomical changes and enabling beam gating. The aim of this study is to quantitatively characterize the static magnetic field and image quality of a 0.22T open MR scanner that has been integrated with a static proton research beamline. The magnetic field and image quality studies are performed using high-precision magnetometry and standardized diagnostic image quality assessment protocols, respectively. The magnetic field homogeneity was found to be typical of the scanner used (98ppm). Operation of the beamline magnets changed the central resonance frequency and magnetic field homogeneity by a maximum of 16Hz and 3ppm, respectively. It was shown that the in-beam MR scanner features sufficient image quality and influences of simultaneous irradiation on the images are restricted to a small sequence-dependent image translation (0.1–0.7mm) and a minor reduction in signal-to-noise ratio (1.3%–5.6%). Nevertheless, specific measures have to be taken to minimize these effects in order to achieve accurate and reproducible imaging which is required for a future clinical application of MR integrated proton therapy.

Künstliche Intelligenz – kaum ein Schlagwort prägt derzeit die Faszination für die digitale Zukunft ebenso wie die Diskussion, wie uns KI helfen kann, unsere Zukunft gut und nachhaltig zu gestalten. KI hat nicht nur als Schlagwort Einzug in unsere gesellschaftlichen Debatten gehalten. Vielmehr kommen wir im täglichen Leben immer mehr mit KI-Anwendungen in Kontakt, bewusst oder unbewusst. Was hat das für Folgen für jede einzelne bzw. jeden einzelnen von uns? Wie wirkt sich der (vermeintliche) Siegeszug von Algorithmen und den darauf aufbauenden Anwendungen und Produkten auf unser Leben aus? Ist KI etwas, was einfach »geschieht«, ohne dass wir es aufhalten können? Oder können wir diese neue Technologie verstehen und gestalten? Redaktionsschluss: 01.09.2021

Die Einführung des millimeter-Wellen-Bandes eröffnet neue Perspektiven für die Radio Frequency Identification (RFID) Kommunikationssysteme. Der Enwurf des Systems im 60-GHz-Band ermöglicht die Implementierung der On-Chip Antenne und darüber hinaus die Implementierung eines RFID-Tags auf einem einzigen Chip. Dennoch ist es aufgrund der gesetzlichen Beschränkung der effektiven isotropen Strahlungsleistung (EIRP) des Lesegeräts und der erhöhten Freiraum-Dielektrikumsverluste eine Herausforderung, eine zuverlässige Kommunikationsreichweite von mehreren Millimetern zu erreichen. Neue Lösungen sind für jeden Block sowohl im Lesegerät als auch im Single-Chip-Tag erforderlich. Obwohl das Lesegerät batteriebetrieben ist, ist es immer noch eine Herausforderung, die maximal zulässigen 20 dBm IERP des Lesersenders energieeffizient zu erzeugen. Darüber hinaus sollte der Empfänger einen ausreichenden Dynamikbereich haben, um das vom Tag kommende Signal zu erkennen. Auf der Tag-Seite sind die Hauptherausforderungen das Co-Design der effizienten On-Chip-Antennen-Implementierung, die hochempfindliche Gleichrichter-Implementierung und das Rückkommunikationskonzept. Diese Arbeit konzentriert sich auf die Machbarkeitsstudie des Single-Chip-RFID-Tags und die Implementierung im Millimeterwellenbereich. Es werden zwei Rückkommunikationskonzepte untersucht - Backscattering-Rückkommunikation und eine Kommunikation unter Verwendung von Ultra-Low-Power (ULP) Radios. Beide werden in einem 22 nm FDSOI Prozess auf einem Substrat mit geringem Widerstand implementiert. Beide Tags arbeiten mit einer Versorgungsspannung von 0,4 V, um die Kommunikationsreichweite zu maximieren. Die Link-Budgets sind so ausgelegt, dass sie die regulatorischen Beschränkungen einhalten. Die Auswahl des Technologieknotens wird begründet. Verschiedene Aspekte im Zusammenhang mit der Technologie werden diskutiert, wie z. B. Geräteleistung, passiver Qualitätsfaktor, Leistungsdichte der Kondensatoren. Der Backscattering RFID-Tag wird zuerst entworfen, da er eine relativ einfachere Topologie hat. Die Probleme der Gleichrichterempfindlichkeit im Rahmen des analogen Frontends, der On-Chip-Antenneneffizienz und der konjugierten Anpassung beider werden untersucht. Eine Kommunikationsreichweite von 5 mm wird angestrebt und realisiert. Um die Kommunikationsreichweite weiter zu erhöhen, wird in der zweiten Phase ein Tag mit einer aktiven Rückkommunikation implementiert. Hier wird die Gleichrichterempfindlichkeit weiter verbessert. Es wird ein 0,4V ULP Radio entworfen, das sich die Antenne mit dem Gleichrichter über einen Single-Pole- Double-Through (SPDT) Schalter teilt. Ein Abstand von 2 cm erwies sich als realisierbar, wobei die gesetzlichen Bestimmungen eingehalten und der dynamische Bereich des Leseempfängers nicht überschritten wurde. Es wird die höchste normalisierte Kommunikationsreichweite pro Leser-EIRP erreicht. Weitere Verbesserungsmöglichkeiten werden diskutiert.

The multidisciplinary field of memristors calls for the necessity for theoreticallyinclined researchers and experimenters to join forces, merging complementary expertise and technical know-how, to develop and implement rigorous and systematic techniques to design variability-aware memristor-based circuits and systems. The availability of a predictive physics-based model for a memristor is a necessary requirement before commencing these investigations. An interesting dynamic phenomenon, occurring ubiquitously in non-volatile memristors, is fading memory. The latter may be defined as the appearance of a unique steady-state behavior, irrespective of the choice of the initial condition from an admissible range of values, for each stimulus from a certain family, for example, the DC or the purely-AC periodic input class. This paper first provides experimental evidence for the emergence of fading memory effects in the response of a TaOₓ redox-based random access memory cell to inputs from both of these classes. Leveraging the predictive capability of a physics-based device model, called JART VCM v1, a thorough system-theoretic analysis, revolving around the Dynamic Route Map graphic tool, is presented. This analysis allows to gain a better understanding of the mechanisms, underlying the emergence of history erase effects, and to identify the main factors, that modulate this nonlinear phenomenon, toward future potential applications.

The carbon nanotube-based field effect transistor (CNTFET) possesses the potential to overcome limitations of state-of-the-art technologies such as silicon-based complementary metal-oxide-semiconductors. However, the carbon nanotube (CNT) technology is still at its infancy and technology development is still necessary to exploit the CNT properties such as high charge carrier mobility, high current carrying capability, one-dimensional charge transport and their versatile integrability. Within this work significant progress has been achieved scientifically and technologically in the advance of high frequency (HF) CNTFETs for analog applications. According to simulations by others, a technology flow has been developed based on electron beam lithography for bottom gated HF CNTFETs which outperform state-of the art top gate architectures with respect to their parasitic capacitances. Moreover, the impact of electrostatic doping on the CNTFETs has been investigated. In particular, the dynamics of water desorption from the CNTFETs and the related reduction of p-type doping was investigated and the different impact of the n-type dopant polyethylenimine onto the channel region and contact region could be separated for the first time. Furthermore, the impact of doped CNT bundles on the device performance has been studied. It could be shown in detail for the first time, that high off-state source-drain leakage currents can be due to bundled semiconducting CNTs and does not necessarily imply the presence of metallic CNTs. The within the framework of this thesis designed and realized HF CNTFETs are operating in the GHz range with cut-off frequencies up to 14 GHz and maximum frequencies of oscillation up to 6 GHz at a channel length of 280 nm. Moreover, the impact of the spacer between the source-/ drain- to the gate electrode on the HF properties of the CNTFETs has been investigated experimentally for the first time. Simulations by others have successfully confirmed that a symmetrical reduction of the source to gate electrode spacer results in an increased device speed. By asymmetrically reducing the source to gate electrode spacer and in parallel increasing the drain-to-gate electrode spacer the device speed can be further enhanced. Moreover, within this work it has been experimentally indicated for the first time that the device properties of HF CNTFETs can be tuned by different device geometries towards either highest linearity or speed.

The globally increasing energy demand that results from the rapid development of modern society has created intensive attention towards the importance of energy efficiency. The areas of energy storage and energy conversion have become one of the most important topics in scientific community at present. As new generation energy storage elements, supercapacitors have exhibited promising practical prospects in the information, transportation, electronics and other sectors due to their charge and discharge performance at high rate, high power density as well as long cycle life. Energy density, including gravimetric energy density, areal energy density and volumetric energy density, is one of the most critical indicator evaluating the performance of supercapacitors. The electrochemical performance of supercapacitors depends mainly on the electrochemical activities and kinetic properties of electrode materials. Carbonaceous materials are deemed to be highly promising, and therefore are extensively investigated energy storage materials for supercapacitors because of their environmental friendliness, low-cost production and outstanding chemical inertness during charging-discharging processes. The specific surface area has been long thought to be the main factor influencing the capacitance of carbonaceous materials. However, the pore structure is of similar importance. High specific surface areas are always arising from a high content of micropores. However, pore radii in the sub-nanometer range impede the ionic charge transfer ability significantly and thus cause a damping of capacitance. In this thesis, hierarchical porous carbons and their composite materials were fabricated by using polyacrylonitrile as carbon precursor for a tailored step-by-step pore forming method, including phase inversion, CaCO3 activation and KOH activation. The materials were thoroughly characterized by XRD, SEM, TEM, BET, XPS and Raman spectroscopy to ascertain the chemical and structural features. The electrochemical properties were studied by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) in detail to analyze the pore effect, which strongly influence their electrochemical properties. Porous carbons with high specific surface areas up to 2315 m2 g-1 and high pore volume of 1.9 cm3·g-1 were prepared. A step-wise pore forming method was employed to ensure a high specific surface area and high content of macro/mesopore at the same time. The relationship between pore structure, electrochemical capacitance and rate capability was investigated by changing the content of micropores. For a same specific surface area, a higher micropore content led to a lower capacitance and poorer rate capability. Based on these results, the capacitance was optimized to be 286.8 F g-1. The areal energy density of the supercapacitors can be improved by increasing the mass loading in a certain area directly. However, insufficient electrochemical reaction may be caused by a lack of unhindered electrical and ionic charge transfer routes, resulting in inefficient material utilization. This problem is addressed by designing hierarchical pore structures with embedded conductive additives. Thus, hierarchical porous carbons were modified by embedding carbon nanotubes (CNTs), followed by coverage with thin layers of birnessite. Owing to the hierarchical pore design and the very high pore volume, the birnessite coverage did not cause pore blocking. At the same time, an intimate contact between carbon and birnessite was established. A high area energy density of 627.8 μWh·cm-2 was obtained based on an optimized mass loading of 13.9 mg cm-2. The volumetric energy density of supercapacitors was determined by the density and porosity of active materials. Similarly, the dense active materials not always generate high specific capacitance because of an increased dead mass. However, too porous active materials do not provide sufficient volumetric capacitance due to a waste of space. Thus, density and porosity must be balanced by hierarchical pore structure design so that all pores are interconnected and can be accessed by ions. At the same time, the content of these pores should be as low as possible to save space. Based on the results, highly hierarchical porous carbons were synthesized and embedded into conductive carbon foam to combine electronic conductivity with ionic transfer. In that way, a volumetric energy density as high as 19.44 µWh cm-3 at a volumetric power density of 500 mW cm-3 was generated.