Die Entwicklung der Mikroelektronik wird durch eine fortschreitende Miniaturisierung der Bauelemente geprägt. Infolge einer Reduzierung der Querschnittflächen von Leitbahnstrukturen erhöht sich die elektrische Leistungsdichte und das Metallisierungssystem bestimmt zunehmend die Übertragungsgeschwindigkeiten. Kupfer repräsentiert hierbei das verbreitetste Leitbahnmaterial und wird vorwiegend mittels elektrochemischer Abscheidung in vergrabene Damaszen-Strukturen eingebracht. Die vorliegende Dissertation beschreibt Möglichkeiten für eine Optimierung von Kupferleitbahnen für höchstintegrierte Schaltkreise. Von besonderem Interesse sind hierbei die Gefügequalität und der Reinheitsgrad. Es erfolgen umfangreiche werkstoffanalytische und elektrochemische Untersuchungen zur Charakterisierung von Depositionsmechanismen, des Einbaus von Fremdstoffen, des Mikrogefüges nach der Abscheidung und der Mikrogefügeumwandlung. In einem abschließenden Forschungsschwerpunkt werden Kupfer-Damaszen-Teststrukturen mit unterschiedlichen Gehalten nichtmetallischer Verunreinigungen hergestellt und entsprechenden Lebensdauerexperimenten unterzogen. Hierdurch gelingt eine Evaluierung des Einflusses jener Verunreinigungen auf die Elektromigrationsbeständigkeit von Kupferleitbahnen. Die Arbeit umfasst daher das gesamte Spektrum von der Grundlagenforschung bis zur Applikation von elektrochemisch abgeschiedenen Kupferdünnschichtmetallisierungen.

Diese Arbeit befasst sich mit den Untersuchungen an Defekten in optischen Materialien die in der Lithographie verwendet werden, speziell mit der Spektroskopie der Verunreinigungen im Kalziumfluorid. Zum einen werden die Eigenschaften der Sauerstoffdefekte in dotierten Proben untersucht, zum anderen werden die Ionen der seltenen Erden in nominal reinen Proben unterschiedlicher Herkunft identifiziert. Die Mechanismen der Aggregatbildung, Dissoziation und der Rekombination so wie die Reaktionsprodukte des Sauerstoffs wurden experimentell belegt und mit Ergebnissen der anderen Autoren verglichen. Bei den nominal reinen Proben konnte anhand der Zusammensetzung des Defektenhaushaltes der seltenen Erden Rückschlüsse auf Herkunft des Materials und Herstellungsbesonderheiten gemacht werden. Es konnte gezeigt werden, dass auch nominal reines Kalziumfluorid den Sauerstoff in Form von Aggregaten enthält.

Die Entwicklung der Mikroelektronik wird durch eine fortschreitende Miniaturisierung der Bauelemente geprägt. Infolge einer Reduzierung der Querschnittflächen von Leitbahnstrukturen erhöht sich die elektrische Leistungsdichte und das Metallisierungssystem bestimmt zunehmend die Übertragungsgeschwindigkeiten. Kupfer repräsentiert hierbei das verbreitetste Leitbahnmaterial und wird vorwiegend mittels elektrochemischer Abscheidung in vergrabene Damaszen-Strukturen eingebracht. Die vorliegende Dissertation beschreibt Möglichkeiten für eine Optimierung von Kupferleitbahnen für höchstintegrierte Schaltkreise. Von besonderem Interesse sind hierbei die Gefügequalität und der Reinheitsgrad. Es erfolgen umfangreiche werkstoffanalytische und elektrochemische Untersuchungen zur Charakterisierung von Depositionsmechanismen, des Einbaus von Fremdstoffen, des Mikrogefüges nach der Abscheidung und der Mikrogefügeumwandlung. In einem abschließenden Forschungsschwerpunkt werden Kupfer-Damaszen-Teststrukturen mit unterschiedlichen Gehalten nichtmetallischer Verunreinigungen hergestellt und entsprechenden Lebensdauerexperimenten unterzogen. Hierdurch gelingt eine Evaluierung des Einflusses jener Verunreinigungen auf die Elektromigrationsbeständigkeit von Kupferleitbahnen. Die Arbeit umfasst daher das gesamte Spektrum von der Grundlagenforschung bis zur Applikation von elektrochemisch abgeschiedenen Kupferdünnschichtmetallisierungen.

Emerging contaminants represent newly identified organic chemical pollutants that are not yet covered by routine monitoring and regulatory programs. Current research on these contaminants is greatly hindered by the shortage of analytical methods due to the complex matrices, extremely low concentration and their “emerging” nature. In this study the innovative analytical and monitoring methods have been developed and validated for determination of emerging pollutants in water (including pharmaceutical and personal care products, pesticides and artificial sweeteners) based on graphene-silica composite as the solid-phase extraction (SPE) sorbent and as the receiving phase in passive sampler. Graphene, a new allotropic member in the carbon family, has been considered to be a promising candidate for sorption material with high loading capacity because of its ultra-high specific surface area and large delocalized π-electron-rich structure. The composite employed in this work was synthesized by using the cross-link agent to covalently combine carboxylic acid groups of graphene-oxide with the amino groups of the modified silica gel. Afterwards, graphene-silica composite was obtained after treated with hydrothermal reaction in the microwave autoclave, which was demonstrated by X-ray diffraction (XRD). The analytical procedure entails SPE followed by high performance liquid chromatography equipped with tandem mass spectrometers (HPLC-MS/MS). Several crucial parameters were optimized to improve recovery of the analytes, including the amount of sorbents, the ratio of graphene oxide/amino-silica and pH value of water samples. The best recovery results were achieved with 100 mg 10 % (w/w) graphene-silica composite, which were over 70 % except four artificial sweeteners, ranitidine and triclosan. Compared with its commercial counterpart Oasis HLB, pH value variation of water samples has less effect on the recoveries, making graphene composite to be a potential receiving phase of monitoring tool. The batch-to-batch reproducibility was verified on six independently SPE cartridges with graphene-silica composites from two repeatable synthetic batches, showing relative standard deviations (RSDs) in the range of 8.3 % to 19.1 %, except ibuprofen and saccharin. The cartridges proved to be reusable for at least 10 times consecutive extractions, with RSD < 14.9 %, except ibuprofen and diclofenac. The Chemcatcher® passive sampler is frequently used for monitoring polar organic chemicals in surface water. Uptake kinetics is necessary to be quantified to calculate time-weighted average (TWA) concentration. A series of calibration experiments were conducted in the beaker renewal experiments as well as in the flow-through system with styrenedivinylbenzene-cross connect (SDB-XC) disks and graphene-silica composite as the receiving phase. The results obtained from the beaker renewal experiments showed that the uptake kinetics of accumulated compounds with all Chemcatcher® configurations can keep linear within 2 weeks. The innovative configuration using graphene-silica composite powder placed between two PES membranes was able to accumulate eleven of the selected compounds with uptake rate (Rs) from 0.01 L/day (acesulfame K and sucralose) to 0.08 L/day (chlothianidin), while its commercial counterpart SDB-XC disks with polyethersulfone (PES) membranes can accumulate seven substances with Rs from 0.02 L/day (sucralose and chlothianidin) to 0.15 L/day (carbamazepine). In the flow-through system, when Chemcatchers® were equipped with SDB-XC disks without PES membranes, the linear uptake range for the majority of compounds was only in one week, except atrazine. The Rs of accumulated compounds were from 0.16 L/day (chloramphenicol) to 1.04 L/day (metoprolol) that are higher than the same substances in the beaker renewal experiments, in which the Rs of chloramphenicol and metoprolol were 0.09 L/day and 0.56 L/day respectively. However, if the PES membranes were employed, the uptake kinetics in both calibration experimental designs were comparable: the Rs of accumulated compounds from the configuration with SDB-XC disks covered by PES membranes were from 0.035 L/day (sucralose) to 0.17 L/day (carbamazepine) and from the configuration with graphene-silica composite were from 0.01 L/day (gemfibrozil) to 0.08 L/day (chlothianidin). Moreover, the uptake range can keep linear within two weeks. The developed Chemcatcher® method was successfully applied in real surface waters. 1-H benzontriazole, tolyltriazole and caffeine were the main contaminants in Elbe River and the Saidenbach drinking water reservoir. The investigated results between summer and autumn monitoring period were not significantly different.:Acknowledgement I Abstract III Zusammenfassung V Content IX List of Figures XIII List of Tables XVII Table of Abbreviations XIX 1. Motivation 1 2. Introduction 3 2.1 Emerging contaminants 3 2.1.1 Definition 3 2.1.2 Sources 3 2.1.3 Concern about the adverse impacts 5 2.2 Analysis of the emerging contaminants 7 2.2.1 General analytical process 7 2.2.2 Enrichment techniques 8 2.2.2.1 Liquid-liquid extraction (LLE) 8 2.2.2.2 Solid-phase extraction (SPE) 9 2.2.2.3 Innovative type of solid-phase extraction 13 2.2.3 Analytical methods 15 2.3 Graphene and its application in analytical chemistry 19 2.3.1 Introduction 19 2.3.2 Synthesis methods of graphene 20 2.3.3 Application in sample pre-treatment 21 2.3.3.1 Graphene-based material as SPE sorbent 21 2.3.3.2 Graphene-coated fibers as SPME sorbent 22 2.3.3.3 Magnetic graphene as MSPE sorbent 23 2.3.3.4 Graphene-based MIPs 24 2.4 Chemcatcher®—a passive sampling technique 25 2.4.1 Introduction 25 2.4.2 Theory 26 2.4.2.1 Equilibrium passive sampling 27 2.4.2.2 Kinetic passive sampling 28 2.4.3 Concept of Chemcatcher® 28 2.4.4 Calibration of Chemcatcher® 33 2.4.5 Performance and reference compounds 36 3. Study objectives and hypotheses 39 3.1 Study objectives 39 3.2 Hypotheses 41 4. Material and methods 43 4.1 Materials 43 4.1.1 Chemicals and solutions 43 4.1.2 Consumable materials and instruments 44 4.2 Synthesis of graphene-silica composite 46 4.3 SPE experiments 49 4.3.1 Packing method 49 4.3.2 SPE procedure 49 4.3.3 Optimization of SPE procedures 51 4.3.4 Repeatability and reusability test 52 4.4 Chemcatcher® experiments 53 4.4.1 Preparation and precondition 53 4.4.2 Calibration of Chemcatcher® 55 4.4.2.1 Preliminary test 55 4.4.2.2 Experimental design of the beaker batch tests 56 4.4.2.3 Experimental design of the flow-through system 57 4.4.3 Monitoring application of Chemcatcher® in surface water 59 4.4.4 Elution process 60 4.4.5 Statistic data evaluation 61 4.5 HPLC-MS/MS analysis 62 5. Results and discussion 63 5.1 Preparation and characterization of graphene-silica composite 63 5.2 SPE performance of the graphene-silica composite 67 5.2.1 Preliminary test of packing methods 67 5.2.2 Optimization of SPE procedures 68 5.2.2.1 The amount of sorbent 68 5.2.2.2 Graphene ratio in the composites 68 5.2.2.3 pH value of the water sample 69 5.2.3 Repeatability and reusability test 72 5.2.3.1 Performance of the off-line SPE 72 5.2.3.2 Repeatability and reusability test results 75 5.2.4 Summarized discussion of the SPE performance 76 5.3 Calibrating results of Chemcatcher® 86 5.3.1 Pre-test results 86 5.3.1.1 Feasibility test of commercial disks as receiving phase 86 5.3.1.2 Stability test 88 5.3.1.3 Elution optimization. 88 5.3.1.4 Recovery of the filters 92 5.3.2 Calibration results of renewal experiments 93 5.3.2.1 SDB-XC disks without and with membranes 93 5.3.2.2 Graphene-silica composite as receiving phase 97 5.3.3 Calibration results of the flow-through system experiments 101 5.3.3.1 Determination of experimental parameters 101 5.3.3.2 Concentration control 103 5.3.3.3 Calibration results 105 5.3.3.4 Preliminary evaluation of performance and reference compounds 112 5.4 Application of Chemcatcher® in surface water 114 5.5 Discussion about problems of commercial disks as receiving phase in Chemcatcher® 118 5.5.1 Deformation of commercial disks 118 5.5.2 The particles in the solution after elution 119 6. Conclusion and perspective 121 7. Annex 125 7.1 Material and methods 125 7.1.1 Chemicals 125 7.1.2 Silica gel and graphene oxide 144 7.1.3 Microwave reduction program 144 7.1.4 Working schedule of the calibration experiments in flow-through system 144 7.1.5 HPLC-MS/MS conditions 146 7.2 Experimental results 149 7.2.1 Stability of the colloid solution of graphene oxide 149 7.2.2 EDX analysis results 149 7.2.3 HPLC-MS/MS results 152 7.2.4 Calibrating results of the beaker renewal experiment 153 7.2.5 Calibrating results of the flow-through system experiments 157 7.2.6 Monitoring results in the Elbe River 161 Reference 163

Intermediate band (IB) materials have attracted considerable research interest since they can dramatically enhance the near infrared light absorption and lead to applications in the fields of so-called intermediate band solar cells or infrared photodetectors. Hyperdoping Si with deep level impurities is one of the most effective approaches to form an IB inside Si. In this thesis, titanium (Ti) or chalcogen doped Si with concentrations far exceeding the Mott transition limits (~ 5×10^19 cm-3 for Ti) are fabricated by ion implantation followed by pulsed laser annealing (PLA) or flash lamp annealing (FLA). The structural and electrical properties of the implanted layer are investigated by channeling Rutherford backscattering spectrometry (cRBS) and Hall measurements. For Si supersaturated with Ti, it is shown that Ti-implanted Si after liquid phase epitaxy shows cellular breakdown at high doping concentrations during the rapid solidification, preventing Ti incorporation into Si matrix. However, the out-diffusion and the cellular breakdown can be effectively suppressed by solid phase epitaxy during FLA, leading to a much higher Ti incorporation. In addition, the formed microstructure of cellular breakdown also complicates the interpretation of the electrical properties. After FLA, the samples remain insulating even with the highest Ti implantation fluence, whereas the sheet resistance decreases with increasing Ti concentration after PLA. According to the results from conductive atomic force microscopy (C-AFM), the decrease of the sheet resistance after PLA is attributed to the percolation of Ti-rich cellular walls, but not to the insulator-to-metal transition due to Ti-doping. Se-hyperdoped Si samples with different Se concentrations are fabricated by ion implantation followed by FLA. The study of the structural properties of the implanted layer reveals that most Se atoms are located at substitutional lattice sites. Temperature-dependent sheet resistance shows that the insulator-to-metal transition occurs at a Se peak concentration of around 6.3 × 10^20 cm-3, proving the formation of an IB in host semiconductors. The correlation between the structural and electrical properties under different annealing processes is also investigated. The results indicate that the degrees of crystalline lattice recovery of the implanted layers and the Se substitutional fraction depend on pulse duration and energy density of the flash. The sample annealed at short pulse durations (1.3 ms) shows better conductivity than long pulse durations (20 ms). The electrical properties of the hyperdoped layers can be well-correlated to the structural properties resulting from different annealing processes.:Chapter 1 Introduction 1 1.1 Shallow and Deep level impurities in semiconductors 1 1.2 Challenges for hyperdoping semiconductors with deep level Impurities 2 1.3 Solid vs. liquid phase epitaxy 5 1.4 Previous work 7 1.4.1 Transition metal in Si 7 1.4.2 Chalcogens in Si 10 1.5 The organization of this thesis 15 Chapter 2 Experimental methods 18 2.1 Ion implantation 18 2.1.1 Basic principle of ion implantation 18 2.1.2 Ion implantation equipment 19 2.1.3 Energy loss 20 2.2 Pulsed laser annealing (PLA) 23 2.3 Flash lamp annealing (FLA) 24 2.4 Rutherford backscattering and channeling spectrometry (RBS/C) 27 2.4.1 Basic principles 27 2.4.2 Analysis of the elements in the target 28 2.4.3 Channeling and RBS/C 29 2.4.4 Analysis of the impurity lattice location 31 2.5 Hall measurements 31 2.5.1 Sample preparation 32 2.5.2 Resistivity 32 2.5.3 Hall measurements 33 Chapter 3 Suppressing the cellular breakdown in silicon supersaturated with titanium 34 3.1 Introduction 34 3.2 Experimental 35 3.3 Results 36 3.4 Conclusions 42 Chapter 4 Titanium-implanted silicon: does the insulator-to-metal transition really happen? 44 4.1 Introduction 44 4.2 Experimental section 45 4.3 Results 47 4.3.1 Recrystallization of Ti-implanted Si 47 4.3.2 Lattice location of Ti impurities 48 4.3.3 Electrical conduction 50 4.3.4 Surface morphology 52 4.3.5 Spatially resolved conduction 53 4.4 Discussion 55 4.5 Conclusion 56 Chapter 5 Realizing the insulator-to-metal transition in Se hyperdoped Si via non-equilibrium material processing 57 5.1 Introduction 57 5.2 Experimental 59 5.3 Results 60 5.4 Conclusions 65 Chapter 6 Structural and electrical properties of Se-hyperdoped Si via ion implantation and flash lamp annealing 67 6.1 Introduction 67 6.2 Experimental 68 6.3 Results 69 6.4 Conclusions 76 Chapter 7 Summary and outlook 78 7.1 Summary 78 7.2 Outlook 81 References 83 Publications 89

Galliumnitrid (GaN) ist ein Schlüsselmaterial zur Produktion von elektronischen Hochfrequenz- und Hochleistungsbauelementen sowie Leuchtdioden. Zum Erreichen der optimalen Bauelementleistung ist ein tiefgreifendes Verständnis sowie die Kontrolle von Punktdefekten unabdingbar um die elektrischen und optischen Substrateigenschaften präzise einzustellen. Im Rahmen dieser Arbeit wurden Punktdefekte in GaN mittels Photolumineszenz (PL)-spektroskopie untersucht. Häufige Übergangsmetallverunreinigungen (Fe, Mn und Cr) wurden anhand ihrer internen Übergänge, die sich durch scharfe Lumineszenz- und Absorptionslinien im nahen Infrarot auszeichnen, identifiziert. Mn und Cr wurden als Ursprung für ungewollte Substratfärbungen bestimmt. Teilweise Entfärbung konnte durch Mn-Si-Kodotierung erreicht werden. Der Zusammenhang zwischen Absorption und Emission des Cr-Zentrums wurde durch polarisationsabhängige PL-Anregungsspektroskopie analysiert. Weiterhin wurde der Einfluss von Kohlenstoffdotierung auf die Eigenschaften von GaN-Substraten durch PL- und PL-Anregungsspektroskopie untersucht. Eine neue Emissionsbande um 1,62 eV, die am effizientesten bei 2,7 eV angeregt wird, wurde für hochdotiertes GaN:C beobachtet und einem internen Übergang C_N-C_Ga-C_N-Komplexen zugeschrieben. / Gallium nitride (GaN) is a key material for the production of high frequency and high power electronics as well as light emitting diodes. Optimum device performance requires a profound understanding and control of the point defect formation in order to determine the electrical and optical substrate properties. Within this thesis, photoluminescence (PL) spectroscopy was applied to analyze point defects in GaN. Common transition metal impurities (Fe, Mn and Cr) were identified by their internal transitions characterized by sharp luminescence and absorption lines in the near infrared region. Among them, Mn and Cr were shown to be the origin of undesirable substrate coloration. Partial decoloration was achieved by an Mn-Si codoping approach. The relationship of absorption and emission processes of the Cr impurity center was further analyzed by polarization dependent PL excitation spectroscopy. Furthermore, the impact of C-doping on GaN substrate properties was investigated by PL and PL excitation spectroscopy. A new emission band around 1.6 eV, most efficiently excited at 2.7 eV, was reported for highly C-doped GaN and proposed to originate from an internal transition of C_N-C_Ga-C_N complexes.

Recently simulation groups have reported the lanthanide series elements as the dopants that have the strongest effect on the stabilization of the ferroelectric non-centrosymmetric orthorhombic phase in hafnium oxide. This finding confirms experimental results for lanthanum and gadolinium showing the highest remanent polarization values of all hafnia-based ferroelectric films until now. However, no comprehensive overview that links structural properties to the electrical performance of the films in detail is available for lanthanide-doped hafnia. La:HfO₂ appears to be a material with a broad window of process parameters, and accordingly, by optimization of the La content in the layer, it is possible to improve the performance of the material significantly. Variations of the La concentration leads to changes in the crystallographic structure in the bulk of the films and at the interfaces to the electrode materials, which impacts the spontaneous polarization, internal bias fields, and with this the field cycling behavior of the capacitor structure. Characterization results are compared to other dopants like Si, Al, and Gd to validate the advantages of the material in applications such as semiconductor memory devices.

No description available.

The aim of this research is to develop a wet-chemical silvering method for a three-dimensional (3D) textile material made of polyethylene terephthalate (PET) to prevent and eliminate biological contaminants in drinking water and other liquid-containing systems. Three-dimensional textile fabrics are particularly well-suited as silvered disinfection materials in water systems, because they have 3D structures, pressure-elastic textile design, and provide large contact areas. Furthermore, water can easily be passed through the structure. The developed wet-chemical procedures are based on aminosilane, which consists of at least two amine groups and is well-suited to form a silver diamine complex. The silvered textile material was coated with cationic silver. After the chemical reduction, the cationic silver turns into metallic silver on the surface of PET spacer fabrics. The surface morphology of silver-coated spacer fabrics was analyzed and the uniform silver layer on the PET fiber surface was found. X-ray diffraction and energy-dispersive X-ray spectroscopy analysis spectrums showed that the silver was immobilized on the PET fiber surface. The layer thickness and the silver amount were also determined. The silvered spacer fabrics can be used in sealing and/or cooling water systems; therefore, the silver ion release in water was analyzed. Furthermore, textile physical tests for the measurement of breaking force and elongation were carried out. No significant change in breaking force and elongation was observed after silvering of PET spacer fabric.

Die vorliegende Arbeit verfolgt das Ziel, Cu(Ag)-Dünnschichten als potentiellen Werkstoff für Leiterbahnen in der Mikroelektronik zu untersuchen. Für die Beurteilung dieses Materialsystems wurden vier Schwerpunkte bezüglich der Schichtcharakterisierung definiert: Herstellung, Gefüge, thermomechanische Eigenschaften, Elektromigrationsresistenz. Grundlage sämtlicher Untersuchungen ist eine geeignete Probenpräparation. In Anlehnung an Technologien, die zur Zeit bei der Herstellung von reinen Cu-Leiterbahnen Anwendung finden, erfolgte die Beschichtung der Cu(Ag)-Schichten (Dicke bis 1 µm) galvanisch aus einem schwefelsauren Elektrolyten unter Additiveinsatz auf thermisch oxidierten Siliziumwafern. Hierbei war nicht nur die Abscheidung von ganzflächigen Dünnschichten, sondern auch die Beschichtung auf strukturierte Substrate von Interesse. Die erzeugten Schichtproben werden in ihren Gefügeeigenschaften, vergleichend zu reinen Kupferschichten, charakterisiert. Hierzu zählen Korngrößen und -orientierungen, thermisches Gefügeverhalten, Einbau, Verteilung und Segregation von Silber und Fremdstoffen sowie die elektrischen Eigenschaften. Von grundsätzlicher Bedeutung für das Elektromigrationsverhalten und damit für die Zuverlässigkeit und das Leistungsvermögen sind die thermomechanischen Eigenschaften. Diese werden an ausgedehnten Schichten mit der Substratkrümmungsmessung bis zu Temperaturen von 500°C beschrieben. Die Diskussion des mechanischen Schichtverhaltens umfasst sowohl thermische als auch temporale Charakteristika. Die Untersuchungen geben einen Einblick in die wirkenden Mechanismen des Stofftransports und des Spannungsabbaus. Den Abschluss der Arbeit stellen erste Experimente zum Elektromigrationsverhalten der Cu(Ag)-Dünnschichten dar. Den Kern dieser Analysen bilden Messungen an sog. Blech-Strukturen (Materialdriftexperimente). Hierbei werden geeignete Technologien für die mikrotechnologische Herstellung von derartigen Cu(Ag)-Strukturen vorgestellt. Anhand erster Messungen wird das Elektromigrationsverhalten von Cu(Ag)-Metallisierungen in seinen Grundcharakteristika beschrieben.