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Haus & Markt: ... für ein schöneres Zuhause: Das Hausbesitzer-Magazin für Mitteldeutschland: Leipzig/Halle/Dresden
No full textAn improved ferroelectric H f₀.₅Zr₀.₅O₂ via La₂O₃ doping and interface engineering
No full textThe discovery of ferroelectricity in the CMOS-compatible material HfO2 at nanometer scales has enabled the realization of low power, high speed, and dense nonvolatile memories. Even though this discovery can be exploited for memory applications, the reliability needs to be thoroughly examined and improved to meet the standard requirements. HfO2 has an intrinsic coercive field of ≈ 1 MV/cm, field-cycling with such a high field leads to defect generation and, subsequently, hard-breakdown of the material. The defect generation with field cycling is evident from the leakage current increase. Prior to the discovery of ferroelectricity, HfO2 was used for high-k applications, where it was experimentally proven that doping it with La suppresses the leakage current through the dielectric. Motivated by this experiment, this thesis was initiated through the additional doping of La into a mixed oxide of Hf0.5Zr0.5O2 to subsequently improve endurance. The experiment was successful but at the cost of non-polar t-phase stabilization, which induced a decrease in pristine Pr, a strengthening of the undesired wake-up effect, and a degradation of data retention. As shown in the literature, the Hf/Zr ratio can potentially change the phase composition of Hf1−xZrxO2. As a next step, the concentration of Hf/Zr in the ternary oxide of La: Hf1−xZrxO2 is altered to roll back the degradation while maintaining the benefits of La. The experimental results deviated a bit from the expectation,
derived by the different origins of structural changes caused by the La and Hf/Zr ratio. After understanding the origin of La-induced structural changes, a different strategy was employed instead of doping La into Hf0.5Zr0.5O2. Here, films comprising a non-mixed La mono-layer and an in-series ferroelectric Hf0.5Zr0.5O2 are fabricated and measured, improving field-cycling endurance while successfully rolling back the cons of La doping. Hence, this thesis concludes with an overall improvement in material properties while avoiding any degradation.:Declaration of Authorship iii
Abstract vii
Acknowledgements ix
1 Introduction 1
2 Fundamentals 5
2.1 Models explaining ferroelectricity . . . . . . . . . . . . . . . . . . . . . . 6
2.1.1 Thermodynamic model . . . . . . . . . . . . . . . . . . . . . . . 6
2.1.2 Preisach model of hysteresis . . . . . . . . . . . . . . . . . . . . 8
2.1.3 Switching kinetic models . . . . . . . . . . . . . . . . . . . . . . 8
2.2 Ferroelectric materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2.1 Prior to ferroelectric H fO2: Perovskite structure ferroelectric
materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.2.2 Ferroelectricity in H fO2 : A scalable fluorite structure ferroelectric
material . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.3 Ferroelectric Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.3.1 One transistor one capacitor FeRAM . . . . . . . . . . . . . . . . 22
2.3.2 Ferroelectric Tunnel Junction . . . . . . . . . . . . . . . . . . . . 23
2.3.3 Ferroelectric Field Effect Transistor . . . . . . . . . . . . . . . . . 24
2.4 Dielectric leakage current mechanisms . . . . . . . . . . . . . . . . . . . 26
2.4.1 Direct tunneling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.4.2 Schottky emission . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.4.3 Fowler-Nordheim tunneling . . . . . . . . . . . . . . . . . . . . 29
2.4.4 Poole-Frenkel conduction . . . . . . . . . . . . . . . . . . . . . . 29
2.4.5 Trap assisted tunneling (hopping) . . . . . . . . . . . . . . . . . 29
3 Experimental 31
3.1 Processes for device fabrication . . . . . . . . . . . . . . . . . . . . . . . 31
3.1.1 Atomic layer deposition . . . . . . . . . . . . . . . . . . . . . . . 31
3.1.2 Physical vapor deposition . . . . . . . . . . . . . . . . . . . . . . 32
3.1.3 Rapid thermal annealing . . . . . . . . . . . . . . . . . . . . . . . 34
3.1.4 Chemical patterning of electrodes . . . . . . . . . . . . . . . . . 34
3.2 Test structure fabrication process . . . . . . . . . . . . . . . . . . . . . . 34
3.3 Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.3.1 Structural characterization . . . . . . . . . . . . . . . . . . . . . 37
3.3.2 Electrical characterization . . . . . . . . . . . . . . . . . . . . . . 37
4 Results and Analysis 43
4.1 Doping Hf0.5Zr0.5O2 with La2O3 . . . . . . . . . . . . . . . . . . . . . . . 43
4.1.1 Structural characterization . . . . . . . . . . . . . . . . . . . . . 45
4.1.2 Electrical characterization . . . . . . . . . . . . . . . . . . . . . . 46
4.1.3 Summary and conclusion . . . . . . . . . . . . . . . . . . . . . . 55
4.2 Doping of Hf1−xZrxO2 with 2.3 mol% La2O3 . . . . . . . . . . . . . . . 57
4.2.1 Structural characterization . . . . . . . . . . . . . . . . . . . . . 57
4.2.2 Electrical characterization . . . . . . . . . . . . . . . . . . . . . . 59
4.2.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.3 The strong wake-up effect in La-doped films . . . . . . . . . . . . . . . 61
4.3.1 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.3.2 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
4.3.3 Summary and conclusions . . . . . . . . . . . . . . . . . . . . . . 68
4.4 Metal-ferroelectric interface engineering through La2O3 and Al2O3 . . 68
4.4.1 Structural characterization . . . . . . . . . . . . . . . . . . . . . 70
4.4.2 Electrical characterization . . . . . . . . . . . . . . . . . . . . . . 71
4.4.3 Summary and conclusions . . . . . . . . . . . . . . . . . . . . . . 79
5 Summary and outlook 85
A The strong wake-up effect in La doped films 89
A.1 Switching current peaks assignment . . . . . . . . . . . . . . . . . . . . 89
A.2 Derivation of depolarization field equation . . . . . . . . . . . . . . . . 90
A.3 Impact of polarization on leakage current measurements . . . . . . . . 90
Bibliograph
Zuverlässigkeitsbewertung gesinterter Ag-Verbindungsschichten und Bestimmung der Ausfallmechanismen in der Leistungselektronik
No full textDer fortschreitende Trend zu höherer Leistungsdichte und Miniaturisierung führt auch in der Leistungselektronik zum Einsatz neuer Technologien, wie dem Silber (Ag) Sintern. Dieses weist eine höhere Temperaturbeständigkeit gegenüber konventionellen Loten auf und ermöglicht eine längere Lebensdauer. Fehlermechanismen, Lebensdauermodelle und prozessabhängige Einflüsse des Ag-Sinterns sind Gegenstand aktueller Forschungsarbeiten. Diese Arbeit beschäftigt sich insbesondere mit der Lastwechselfestigkeit bei passiven Temperaturwechseln für verschiedene Hübe und dem daraus entstehenden neuen Fehlermechanismus der Sinterschicht im Zusammenspiel mit dem Kupfer des Substrats. Untersuchungen der Mikrostruktur zeigen dabei eine starke Verformung des Kupfers, bei der ein Wechselspiel mit der Sinterschicht entsteht und sich eine dreidimensionale Hügel- und Tallandschaft ausbildet. Dies führt zu Bereichen hoher und niedriger Porosität innerhalb der Sinterschicht und somit zu einer Inhomogenität hinsichtlich der Materialeigenschaften. Diese Parameter spielen für die spätere Simulation eine entscheidende Rolle. Der Fehlermechanismus wird systematisch untersucht und dargestellt. Ebenfalls werden Phänomene bei Hochtemperaturauslagerung bei 180 °C beobachtet, die keine besonderen Veränderungen der Sinterschicht gegenüber Parametern wie der Porosität aufweisen. Die beiden verwendeten Halbleiter verfügen über eine unterschiedliche Oberflächenmetallisierung (Silber und Gold), was für die Gold (Au) Metallisierung zum Wachstum eines porenfreien Gebiets und darüber hinaus zur Ausbildung einer dünnen Kupferoxidschicht führt. Zudem werden in der Arbeit verschiedene Schädigungsparameter und Ansätze simulativ untersucht, um ein geeignetes Lebensdauermodell abzuleiten und den vorliegenden Fehlermechanismus abzubilden. Es werden klassische Ansätze wie die der akkumulierten plastischen Dehnung und Dehnungsenergiedichte pro Zyklus, Tri- und Multiaxialitätsfaktoren sowie die Modellierung inhomogener Sinterschichten, mit Hilfe verschiedener Materialmodelle untersucht. Ein neu entwickelter Ansatz wird letztlich vorgestellt, bei dem Daten aus den passiven Temperaturwechseln in Kombination mit der Beanspruchung aus der Simulation zu einem Lebensdauermodell zusammengefügt werden. Die Ergebnisse zeigen die Notwendigkeit von Simulationen auf Mikrostrukturebene und die Limitierung der klassischen kontinuumsmechanischen Modellen. Als Eingangsparameter sind hierzu die Materialdaten und deren Charakterisierung von großer Bedeutung. Dabei werden maßgeblich die Versuchsdaten von Flachzugproben mit einer Dicke, vergleichbar der späteren Sinterschicht im Modul genutzt, da diese denselben Sinterprozess durchlaufen können und somit eine vergleichbare Mikrostruktur aufweisen. Zusätzlich werden erste Ergebnisse einer neu entwickelten Probe und deren Herstellungsprozess vorgestellt. Da es sich dabei um eine Rundzugprobe handelt, können an dieser in Zukunft umfangreiche Ermüdungsversuche in Zug-Druck-Richtung durchgeführt werden. Dies ist im Vergleich zu den herkömmlichen Ag-gesinterten Proben ein großer Vorteil, da Materialmodelle und Ermüdungsschädigungen am reinen Material untersucht werden können
Öffentlicher Gesundheitsdienst Sachsen: Digitalisierungsstrategie
No full textDer Öffentliche Gesundheitsdienst (ÖGD) in Sachsen ist zunehmend stärker geprägt vom digitalen Wandel und seinen weitreichenden Folgen. So zeigt sich im ÖGD eine stetig steigende Anzahl an digitalen Transformationsprozessen, welche die daran beteiligten Akteure wie die Gesundheitsämter oder die Landesuntersuchungsanstalt (LUA) vor neue Herausforderungen und Chancen stellt. Um die gegebenen Digitalisierungspotentiale optimal zu nutzen und die Herausforderungen als Chancen zu begreifen, hat das Sächsische Staatsministerium für Soziales, Gesundheit und Gesellschaftlichen Zusammenhalt (SMS) eine Digitalisierungsstrategie für den ÖGD erarbeiten lassen, um die Digitalisierung in diesem Bereich voranzutreiben.
Redaktionsschluss: 30.09.202
Desecularisation of the State and Sacred Secularism: Politics and Religion in Mexico within the Latin-American Context
No full textRecent political conflicts have highlighted the influence of religious actors and organisations in the public spheres of Latin American countries. The Pentecostal Evangelical movement in Colombia was crucial to the success of the ‘No’ campaign in the 2016 plebiscite, in which citizens rejected the peace agreement between the government and the Revolutionary Armed Forces of Colombia (FARC). In Brazil, evangelical congregations played a central role during the 2016 impeachment of President Dilma Rousseff, and in the subsequent rise of Jair Bolsonaro. In Bolivia, evangelical leaders and conservative elements of the Catholic Church alike supported the 2019 coup against Evo Morales. In Mexico, the 2018 rise of left-wing President Andrés Manuel López Obrador has been accompanied by criticism of his proximity to religious actors, and his moralising political rhetoric. Some authors have even described the Mexican leader as a politician with messianic overtones. Against this background, it is worth asking what the implications of the recent convergence between politics and religion in Latin America are. To answer this question, we must avoid the oversimplification of suggesting a singular process of religious advance in Latin American societies. It is important to instead highlight the complex interaction of: 1) the process of secularisation (involving both secularism and secularity) in the region, 2) the trend towards pluralisation of the religious field, 3) the concurrence of counter-secular expressions in the public space, 4) and the occurrence of conflict in the political arena. Although secularisation in Latin America historically emerged as a process of distinction of the political sphere, I argue here that it is currently expressed as a democratic ideal through the process of the dispersal in society of certain secular notions favouring state autonomy, especially in those countries that maintain the secularism legally established in the nineteenth century. My approach raises the question of how the boundaries between religion and the state in Mexico have been defined historically, and what the current status of this differentiation is. I also advance the analytical notion of sacred secularism, as a principle and expectation in the public space
Das Gruppentraining sozialer Kompetenzen im Bereich der Jugendhilfe im Strafverfahren
No full textIn dieser Arbeit wurde das GSK mit Jugendlichen, die hinsichtlich des Tatbestandes
Ladendiebstahl straffällig geworden sind, thematisiert.:1 Einleitung 1
2 Grundlagen der JuHiS 3
2.1 Rechtliche und begriffliche Einordnung 3
2.2 Zielgruppe 4
2.3 Absichten und Aufgaben 5
3 Soziale Kompetenz(en) 7
3.1 Begriffsannäherung 7
3.2 Eigenschaften und Bedeutung 9
4 Ladendiebstahl als dissoziales Verhalten 10
4.1 Gesellschaftliche Entwicklung und Relevanz 10
4.2 Begriffsannäherung 12
4.3 Ursachen und Verlauf 13
4.4 Einflussfaktoren 15
5 Zusammenhang soziale Kompetenzen und dissoziales Verhalten 17
6 GSK mit straffälligen Jugendlichen mit Tatbestand Ladendiebstahl 19
6.1 Einordnung und Zielsetzung 19
6.2 Durchführungsmodalitäten 21
6.3 Methodischer Ansatz und Trainingselemente 24
6.3.1 Situationstypen 26
6.3.2 Rollenspiele (mit Videofeedback) 28
6.3.3 Hausaufgaben 30
7 Zusammenfassung und Ausblick 31
Quellenverzeichnis II
Wegweiser für werdende Eltern
No full textDas Familienbegleitheft 1 des Jugendamtes des Landkreises Zwickau ist für Schwangere, Paare mit Kinderwunsch sowie Schwangere und werdende Väter in Not gedacht
Impact of LNG imports and shale gas on a European natural gas diversification strategy
No full textIn this article the impact of liquefied natural gas (LNG) imports and shale gas exploitation on a European dependency from main gas suppliers is analysed. For this purpose we introduce the “Gas Market Model (GaMaMod)” that represents the European natural gas market within a bottom-up approach. In order to analyse the European gas supply, we look at two main scenarios for the year 2025 with regard to an extension of LNG import capacities and an increased exploitation of European shale gas. Within the scenarios, we modify the basic conditions with respect to the level of demand and present the supply mix in the European gas market. Our results show that LNG and shale gas have an effect on the diversification of gas supply, but the effect is quite limited and main European gas suppliers, especially Norway and Russia, will still remain dominantly in the European gas supply
Synthesis of 2D and 3D Covalent Organic Frameworks for Advanced Applications in Adsorption, Electrochemistry and Catalysis
No full textCovalent Organic Frameworks (COFs) are a class of crystalline porous organic polymers constructed through reticular chemistry, wherein organic linkers are connected by strong covalent bonds. The structural and functional diversity of COFs can be significantly enriched by the strategic design approach. By applying a certain combination of organic building units, it is possible to achieve materials with advanced properties and tailored functionalities. Depending on the structural composition and geometric configuration of the final material, COFs can be applied as sensors, catalysts, and in the fields of adsorption, energy and environmental applications.
In this dissertation work I focused on the development of COFs series with various structural architectures, connectivities and pore interfaces. Through a thorough search of organic building units, COFs with unique properties and advanced functionalities were designed and their structure-property correlations were analyzed: 1) using a nitrogen-rich carbazole-based linker, π-conjugated COFs with donor-acceptor units were synthesized. Resulting materials displayed acidochromism phenomena and unique sensing abilities, as well as enhanced water adsorption properties, which renders them promising for humidity control applications. 2) Introducing donor-acceptor charge transfer moieties within 2D COF structure resulted in suitable band gap energy, allowing for the utilization of COF material as catalyst in photocatalytic H2O2 production reaction. 3) Employing triphenylamine-based linker resulted in COF structure with redox-active functionalities, which demonstrated reversible electrochromic behavior upon application of voltage. 4) Implementing a bipyridine moiety within the COF structure offered a platform for metal ions coordination, making the COF material suitable for application in heterogeneous catalysis. 5) By using a combination of rigid and flexible building units, novel 3D COFs and porous organic polymers were synthesized and characterized. Correlation between topological predesign and crystallinity of final COFs was discussed. 6) Structure and thermal properties of boronate ester-linked 3D COF were analyzed and negative thermal expansion phenomena of boroxine-linked 3D COF was investigated. 7) An 8-topic linker with diol functionalities was synthesized and the synthesis of novel boronate ester-linked 3D COF with hierarchical porosity was attempted.
This work provides new insights into the chemistry, structural design and synthesis of 2D and 3D COFs, as well as in the utilization of COFs in adsorption, catalysis, environmental and energy-related applications.:Acknowledgments .................................................................................................. iv
Abstract .................................................................................................................. vi
Table of contents .................................................................................................. viii
List of abbreviations ................................................................................................ x
1 Motivation ........................................................................................................ 1
2 State of the art ................................................................................................. 4
2.1 Covalent Organic Frameworks .................................................................... 5
2.2 Synthesis and topologic diagrams ............................................................... 6
2.2.1 Two dimensional COFs ............................................................................ 8
2.2.2 Three dimensional COFs ....................................................................... 10
2.2.3 Imine-linked COFs ................................................................................. 12
2.2.4 Boroxine and boronate ester-linked COFs ............................................. 14
2.3 Electronic structure of COFs and band-gap engineering ........................... 16
2.4 Adsorption ................................................................................................. 19
2.4.1 Adsorption isotherms, BET area and pore size distribution ............ 20
2.4.2 Water vapor adsorption ................................................................... 24
2.4.3 Flexibility in COFs .................................................................................. 28
2.5 Negative thermal expansion ................................................................... 31
2.6 Applications ............................................................................................... 34
3 Results and discussion.................................................................................. 38
3.1 Acidochromism and humidity sensing properties of DUT-175 and DUT-
176 ............................................................................................................... 39
3.1.1 Synthesis and characterization .............................................................. 40
3.1.2 Chemical stability and acidochromism ................................................... 44
3.1.3 Water adsorption properties ................................................................... 48
3.1.4 Humidity sensing properties ................................................................... 51
3.1.5 Summary ................................................................................................ 52
3.2 Potential of DUT-175 as photocatalyst in ORR and organic
transformations ................................................................................................... 54
3.2.1 DUT-175 photocatalytic properties ......................................................... 55
3.2.2 Outlook ................................................................................................... 59
3.3 Imine-linked redox active COF DUT-168 for the electrochromic layer in
electrochromic devices ....................................................................................... 60
3.3.1 Synthesis and characterization .............................................................. 61
3.2.2 Electrochemical properties ..................................................................... 64
ix
3.2.3 Electrochromism ...................................................................................... 65
3.2.4 Summary ................................................................................................. 69
3.4 Bipyridine based COF DUT-156 synthesis and its potential in
heterogeneous catalysis ..................................................................................... 70
3.4.1 Synthesis and characterization .............................................................. 71
3.4.2 Metal incorporation in COF .................................................................... 74
3.4.3 Potential of Ni@DUT-156 in photocatalytic cross-coupling reactions .... 78
3.4.4 Summary ................................................................................................ 79
3.5 COF-102 and COF-108-int adsorption properties and negative thermal
expansion investigation ...................................................................................... 81
3.5.1 Synthesis and characterization .............................................................. 82
3.5.2 Adsorption properties ............................................................................. 85
3.5.3 Thermal properties ................................................................................. 87
3.5.4 Summary ................................................................................................ 90
3.6 3D COF and porous organic polymers based on carbazole ligand ........ 91
3.6.1 Synthesis and characterization .............................................................. 92
3.6.2 Outlook ................................................................................................... 97
3.7 3D phenazine based boronate ester linked COF design and synthesis . 99
3.7.1 COF and linker design ......................................................................... 100
3.7.2 Linker synthesis and characterization .................................................. 102
3.7.3 COF synthesis and characterization .................................................... 106
3.7.4 Outlook ................................................................................................. 107
4 Conclusion and outlook ............................................................................... 108
5 Experimental section ................................................................................... 113
5.1 Instruments .......................................................................................... 114
5.2 List of chemicals................................................................................... 117
5.3 List of solvents ..................................................................................... 118
5.4 Synthesis and characterization of organic ligands ............................... 118
5.5 Synthesis of COFs and organic polymers ............................................ 123
6 References .................................................................................................. 127
7 Appendix ..................................................................................................... 165
7.1 Supplementary data ................................................................................ 166
7.2 List of publications ................................................................................... 190
7.3 Conferences contribution ......................................................................... 191
8 Erklärung gemäß §5 Abs. 1 Punkt 5 ..........................................................19
