Sewage exfiltration from a sanitary and combined sewer systems and its percolation into porous medium results in a clogged or colmation layer in the nearby soil. In order to develop a comprehensive understanding of raw sewage transport mechanisms in porous media, investigations were carried out on the micro-scale properties of the multiphase system. In our laboratory experiments, the role of surfactants as a major organic chemical compound in wastewater was evaluated by using a surfactant solution as an artificial wastewater percolating into a porous media, represented by using columns and Plexiglas model. We studied flows of water and surfactants solution in saturated porous medium to detect the dynamic effects by means of measuring pressure and permeability as well as by visualization of flow regions and consequence for porosity along interfaces between water and surfactants solution. The tests revealed that mechanisms at interfaces between fluids and solids as well as between water and surfactants solution (i.e. wastewater) are significantly influencing the flow behavior. At the interfaces surfactant molecules are adsorbed or accumulate, respectively, and subsequently inducing electrical charges to those layers, altering the properties of fluids and these interfaces. Depending on the conditions, channels might be narrowed and thus decreasing the flow rate with a later erosion and increase of flow rates, or the flow and thus the erosive capacity might become intensified along the interface between surfactants solution and neighbouring water. In conclusion, the results of tests proved the surfactants to be an important controlling factor in the hydraulic properties of wastewater percolating into soil.

Die geordneten mesoporösen Silikamaterialien SBA-15 und MCM-41 zeichnen sich durch lange zylindrische Poren aus, die auf einem 2D-hexagonalen Gitter arrangiert sind. Auf Grund dieser Eigenschaften finden sie vielfach Anwendung in der Industrie, bieten jedoch auch die Möglichkeit Sorptionsvorgänge und die dadurch induzierten Verformungen auf der Nanometerebene zu untersuchen. Dazu werden im ersten Teil dieser Arbeit Kleinwinkelröntgenstreuungsdaten mit Hilfe eines Formfaktormodells angefittet, um die Adsorption von Fluid in den Poren in Abhängigkeit vom Dampfdruck nachvollziehen zu können. Basierend auf diesen Ergebnissen wird ein Gittermodell eingeführt, welches die Vorgänge während der Sorption mit Hilfe heuristischer Füllmechanismen reproduziert und im Abgleich mit experimentellen Daten Auskunft über die Verteilung der Porosität auf Mikro- und Mesoporen in SBA-15 gibt. Weiterhin wird der Einfluss der begrenzten Geometrie auf die Selbstassemblierung von Tensiden in SBA-15 untersucht. Hierzu werden Neutronenstreudaten durch die Kombination eines Formfaktormodells für die Bragg-Streuung und des Teubner-Strey-Modells für die diffuse Streuung modelliert und interpretiert. Der zweite Teil der Arbeit beschäftigt sich mit den elastischen Verformungen der mesoporösen Materialien durch die Fluidsorption. Dazu wird eine Molekulardynamik-Simulation eines Lennard-Jones-Fluids in einer Schlitzpore vorgestellt, um den Ursprung dieser Verformungen auf der mikroskopischen Ebene zu untersuchen. Diese Ergebnisse fließen anschließend in ein makroskopisches Modell eines ganzen Kristalliten des mesoporösen Materials ein, wodurch ein einfaches Multiskalenmodell entsteht. Die makroskopische Ebene wird dabei durch eine Finite-Elemente-Simulation beschrieben, die im Abgleich mit experimentellen Daten weitere Aussagen über die elastischen Eigenschaften des Materials erlaubt. / The ordered mesoporous silica materials SBA-15 and MCM-41 consist of long cylindrical pores arranged on a 2D-hexagonal lattice. Due to these features, they are used for a range of industrial applications but provide also a possibility to study sorption processes and sorption-induced deformations on the nanoscale. In the first part of this work small-angle X-ray scattering data are fitted with a form factor model in order to examine fluid adsorption in the pores. Based on these results a lattice model is introduced which reproduces the sorption process using heuristic filling mechanisms and clarifies how the porosity of SBA-15 is composed out of micro- and mesopores. Furthermore, the influence of the confined geometry on the self-assembly of surfactants in SBA-15 is studied. For this, neutron scattering data are modeled and interpreted by the combination of a form factor model for the Bragg scattering and the Teubner-Strey model for the diffuse scattering. The second part of this work focuses on the elastic deformations caused by fluid sorption in the mesoporous materials. A Molecular Dynamics simulation of a Lennard-Jones fluid in a slit-pore is presented in order to reveal the origin of these deformations on the microscopic scale. These results are subsequently implemented into a macroscopic model of whole crystallite, thereby creating a simple multi-scale model. The macroscopic scale is modeled with a Finite Elements simulation, which by comparison with experimental data delivers further insights into the elastic properties of the material.

The investigations are related to the influence of nonionic polyethoxylated surfactant on Tin- and Tin-Silver depositions. Cyclovoltammetry, electrochemical depositions in Hull cell, with quartz crystal microbalance, impedance spectroscopy, X-ray diffraction, REM and others were used as methods of characterization. / Die Untersuchungen befasssen sich mit dem Einfluss von nichtionischen polyethoxylierten Tenside auf die Zinn- und Zinn-Silber-Abscheidung, die durch Zyklovoltammetrie, Abscheidungen in der Hullzelle, mit der elektrochemischen Quarzmikrowaage, der Impedanzspektroskopie, Röntgendiffraktometrie, Rasterelektronenmikroskopie und Tensiometrie charakterisiert wurden.

No description available.

The investigations are related to the influence of nonionic polyethoxylated surfactant on Tin- and Tin-Silver depositions. Cyclovoltammetry, electrochemical depositions in Hull cell, with quartz crystal microbalance, impedance spectroscopy, X-ray diffraction, REM and others were used as methods of characterization. / Die Untersuchungen befasssen sich mit dem Einfluss von nichtionischen polyethoxylierten Tenside auf die Zinn- und Zinn-Silber-Abscheidung, die durch Zyklovoltammetrie, Abscheidungen in der Hullzelle, mit der elektrochemischen Quarzmikrowaage, der Impedanzspektroskopie, Röntgendiffraktometrie, Rasterelektronenmikroskopie und Tensiometrie charakterisiert wurden.

No description available.

No description available.

Ever since their discovery in 1991, carbon nanotubes are of great interest to the scientific community due to their outstanding optical, mechanical and electrical properties. Considering their impressive properties, as for instance the high current carrying capability and the possibility of ballistic charge transport, carbon nanotubes are a desired channel material in field-effect transistors, especially with respect to high frequency communication electronics. Thus, many scientific studies on CNT-based field-effect transistors have been published so far. But despite the successful verification of excellent individual electric key values, corresponding experiments are mostly performed under synthetic conditions (considering e.g. temperature or gas atmosphere), which are not realizable during realistic application scenarios. Furthermore, technologically relevant factors like homogeneity, reproducibility and yield of functioning devices are often subordinated to the achievement of a single electric record value. Hence, this work focuses on the development of a fabrication technology for carbon nanotube field-effect transistors, that takes those factors into account. Thereby, this work expands the state of the art by introduction and statistical assessment of two cleaning processes: a) wet chemical removal of surfactant residues (sodium dodecylsulfate) from CNTs, integrated using the dielectrophoretic approach, by investigation and comparison of four procedures (de-ionized water, HNO3, oDCB, Ethanol); b) the reduction of process-related substrate contaminations by application of an oxygen plasma. Beyond that, the passivation of the final, working devices is developed further, as their typical definition as diffusion barrier is expanded by the reduction of parasitic capacitances in the transistor. In this context, two so far barely considered materials, hydrogen silsesquioxane and Xdi-dcs, a polymer mixture of poly(vinylphenol) and polymethylsilsesquioxane, are investigated and assessed. The novelty of the Xdi-dcs mixture causes the necessity of fundamental considerations on controllable etching procedures and resulting adaptions of the technological fabrication sequence.:Bibliographic description 3 List of abbreviations 10 List of symbols 10 1 Introduction 13 2 Basics of carbon nanotubes 15 2.1 Structural fundamentals 15 2.1.1 Hybridization of carbon 15 2.1.2 Structure of carbon nanotubes 17 2.2 Electronic properties 19 2.2.1 Band structure of graphene 19 2.2.2 Band structure of carbon nanotubes 20 2.2.3 Electronic transport in CNTs 22 2.3 Procedures for CNT integration 23 2.3.1 Growth by chemical vapor deposition 24 2.3.2 Transfer techniques 24 2.3.3 Dispersion-related integration procedures 25 2.4 Interaction of CNT and surfactant 28 3 Basics of CNT field-effect transistors 31 3.1 Principle of operation of conventional FETs 31 3.2 Distinctive features of CNT-based FETs 32 3.2.1 Metal - semiconductor contact 33 3.2.2 Linearity 38 3.3 Performance determining factors 41 3.3.1 Device architecture 41 3.3.2 Contact geometry 46 3.3.3 Other transistor dimensions 48 3.3.4 CNT-related characteristics 49 3.4 Hysteresis in transfer characteristics 51 3.4.1 Definition of hysteresis 51 3.4.2 Origins of hysteresis 52 3.4.3 Appearance of hysteresis 53 3.5 Passivation 56 3.5.1 Requirements 56 3.5.2 Importance of pre-treatments and process conditions 57 3.5.3 Overview of established passivation materials 58 4 Experimental work 63 4.1 Transistor design 63 4.2 Technology flow 66 4.3 Experimental procedures 71 4.3.1 Procedures for dissolution of SDS 71 4.3.2 Plasma treatment against surface contaminations 72 4.3.3 Evaluation of diffusion barriers 72 4.4 Instrumentation and characterization 74 4.4.1 Dielectrophoresis instrumentation 74 4.4.2 Topographical Characterization 74 4.4.3 Chemical characterization 75 4.4.4 Electrical characterization 76 5 Reduction of hysteresis 77 5.1 Removal of surfactant molecules from CNTs 77 5.1.1 Influence on molecule and CNT chemistry 78 5.1.2 Effect on transistor performance 80 5.2 Plasma-assisted removal of substrate contaminations 87 5.2.1 Influence on substrate surface 88 5.2.2 Effect on transistor performance 92 6 Passivation 97 6.1 Protection against environmental effects 97 6.1.1 Alterability of unpassivated CNT-FETs 98 6.1.2 Effects of O2 exclusion by dense passivation 99 6.1.3 Intentional doping using Y2O3 101 6.2 Passivation considering electrostatic aspects 106 6.2.1 Integration of Xdi-dcs as novel passivation 107 6.2.2 Comparison of two spin-coated dielectrics 111 6.3 Potential of double-layer approaches 113 6.3.1 Evaluation of the gas barrier performance 113 6.3.2 Influence on the transistor behavior 116 7 Summary and Outlook 121 Danksagung 127 Appendix 129 Bibliography 137 List of figures 156 List of tables 161 Selbstständigkeitserklärung 163 8 Thesen 165 9 Curriculum vitae 169 / Bereits seit ihrer Entdeckung 1991 sind Kohlenstoffnanoröhren, aufgrund ihrer herausragenden optischen, mechanischen und elektrischen Eigenschaften, für die wissenschaftliche Community von großem Interesse. Ihre Verwendung als Kanalmaterial in Feld-Effekt Transistoren ist in Anbetracht ihrer außergewöhnlichen Eigenschaften, wie z. B. die hohe Stromtragfähigkeit, sowie die Möglichkeit des ballistischen Transports von Ladungsträgern besonders für die hochfrequente Kommunikationselektronik erstrebenswert. Dementsprechend viele wissenschaftliche Arbeiten befassen sich mit der Erforschung von auf Kohlenstoffnanoröhren basierenden Transistoren. Doch trotz des erfolgreichen Nachweises ausgezeichneter Werte für viele individuelle elektrische Kenngrößen, finden entsprechenden Experimente zumeist unter anwendungsfernen Bedingungen bezüglich Temperatur bzw. Gasatmosphäre statt. Darüber hinaus werden dem Erreichen eines elektrischen Rekordwertes oft technologisch relevante Größen wie Homogenität, Reproduzierbarkeit und Ausbeute an funktionsfähigen Bauteilen untergeordnet. Der Fokus dieser Arbeit liegt daher auf der Erarbeitung einer Technologie zur Herstellung Kohlenstoffnanoröhrenbasierter Feld-Effekt Transistoren, unter Berücksichtigung dieser Aspekte. Dabei erweitert diese Arbeit den Stand der Technik durch die Einführung und statistische Beurteilung zweier Reinigungsprozesse: a) der nasschemischen Beseitigung von Tensidresten (Natriumdodecylsulfat) an mittels Dielektrophorese integrierten CNTs, wobei insgesamt vier Prozeduren (de-ionisiertes Wasser, HNO3, oDCB, Ethanol) betrachtet und miteinander verglichen wurden; b) der Beseitigung von prozessbedingten Substratkontaminationen durch ein Sauerstoffplasma. Darüber hinaus wird die Passivierung der funktionsfähigen Bauelemente weiterentwickelt, indem ihre typische Definition als Diffusionsbarriere um den Aspekt der Verringerung parasitärer Kapazitäten im Transistor erweitert wird. In diesem Zusammenhang werden mit Wasserstoff-Silsesquioxane und Xdi-dcs, einem Polymergemisch aus Poly(vinylphenol) und Polymethylsilsesquioxane, zwei bislang wenig beachtete Materialien, untersucht und bewertet. Die Neuheit des Xdi-dcs Gemisches macht dabei fundamentale Untersuchungen zur Strukturierbarkeit und entsprechende technologische Anpassungen im Gesamtablauf nötig.:Bibliographic description 3 List of abbreviations 10 List of symbols 10 1 Introduction 13 2 Basics of carbon nanotubes 15 2.1 Structural fundamentals 15 2.1.1 Hybridization of carbon 15 2.1.2 Structure of carbon nanotubes 17 2.2 Electronic properties 19 2.2.1 Band structure of graphene 19 2.2.2 Band structure of carbon nanotubes 20 2.2.3 Electronic transport in CNTs 22 2.3 Procedures for CNT integration 23 2.3.1 Growth by chemical vapor deposition 24 2.3.2 Transfer techniques 24 2.3.3 Dispersion-related integration procedures 25 2.4 Interaction of CNT and surfactant 28 3 Basics of CNT field-effect transistors 31 3.1 Principle of operation of conventional FETs 31 3.2 Distinctive features of CNT-based FETs 32 3.2.1 Metal - semiconductor contact 33 3.2.2 Linearity 38 3.3 Performance determining factors 41 3.3.1 Device architecture 41 3.3.2 Contact geometry 46 3.3.3 Other transistor dimensions 48 3.3.4 CNT-related characteristics 49 3.4 Hysteresis in transfer characteristics 51 3.4.1 Definition of hysteresis 51 3.4.2 Origins of hysteresis 52 3.4.3 Appearance of hysteresis 53 3.5 Passivation 56 3.5.1 Requirements 56 3.5.2 Importance of pre-treatments and process conditions 57 3.5.3 Overview of established passivation materials 58 4 Experimental work 63 4.1 Transistor design 63 4.2 Technology flow 66 4.3 Experimental procedures 71 4.3.1 Procedures for dissolution of SDS 71 4.3.2 Plasma treatment against surface contaminations 72 4.3.3 Evaluation of diffusion barriers 72 4.4 Instrumentation and characterization 74 4.4.1 Dielectrophoresis instrumentation 74 4.4.2 Topographical Characterization 74 4.4.3 Chemical characterization 75 4.4.4 Electrical characterization 76 5 Reduction of hysteresis 77 5.1 Removal of surfactant molecules from CNTs 77 5.1.1 Influence on molecule and CNT chemistry 78 5.1.2 Effect on transistor performance 80 5.2 Plasma-assisted removal of substrate contaminations 87 5.2.1 Influence on substrate surface 88 5.2.2 Effect on transistor performance 92 6 Passivation 97 6.1 Protection against environmental effects 97 6.1.1 Alterability of unpassivated CNT-FETs 98 6.1.2 Effects of O2 exclusion by dense passivation 99 6.1.3 Intentional doping using Y2O3 101 6.2 Passivation considering electrostatic aspects 106 6.2.1 Integration of Xdi-dcs as novel passivation 107 6.2.2 Comparison of two spin-coated dielectrics 111 6.3 Potential of double-layer approaches 113 6.3.1 Evaluation of the gas barrier performance 113 6.3.2 Influence on the transistor behavior 116 7 Summary and Outlook 121 Danksagung 127 Appendix 129 Bibliography 137 List of figures 156 List of tables 161 Selbstständigkeitserklärung 163 8 Thesen 165 9 Curriculum vitae 169

The application of surfactants and polymers in carbonate reservoirs has a high potential with emerging technology of the manufacture of these chemicals. Tertiary or enhanced oil recovery with chemicals (CEOR) will become more relevant with decreasing new exploration of oil deposits and high remaining oil saturations in huge carbonate oil reservoirs. However, in several oil deposits, high reservoir brine salinity and moderate to high reservoir temperature are encountered. Under such conditions, many chemicals will be insoluble or degrade fast. A selection of commercial and research surfactants and polymers has been investigated for their application under brine salinity of up to 18 percent by weight with significant hardness and a moderate reservoir temperature of 70 °C. Chemical systems were tested towards outcrop limestone rock samples and calcite platelets in combination with a crude oil, which was modified by different organic acids regarding its wetting potential. Wettability alteration from preferentially oil-wet core plugs was pursued with ethoxylated tertiary amines and quaternary ammonium compounds. The main mechanism of wettability alteration towards more water-wet was proposed as extraction of carboxylate anions from the oil phase and the solid samples into aqueous micelles. Thus, high surfactant concentrations would result in improved recovery. From screening of different surfactant combinations in tertiary core flooding, one promising system of an alkyl ether sulfate and hexadecyltrimethylammonium combined with a terpolymer (TP) from acrylic acid, ATBS and NVP is proposed for the examined conditions. Low to moderate adsorption of the single surfactants and their combination as well as a favorable, stabilized phase behavior when combined with the polymer emphasize the applicability of the system. However, long term stability can be an issue with respect to the sulfate surfactant degradation at 70 °C. Analysis of mixed ionic surfactant systems after adsorption testing has been successfully pursued with a combined TC/TNb-determination.