In the present era where MEMS (Micro Electro-Mechanical Systems) technology is in¬evitable from the perspective of applications in non-silicon based micro-devices (such as biosensors, microfluidics, microvalves etc.), it is imperative to develop different micro¬fabrication technologies which are simple in operation, have low operational cost and high versatility in terms of incorporating different materials. The microfabrication tech¬nologies (e.g: bulk micromachining, surface micromachining, X-ray LIGA (lithoqraphie galvanoformung abformung) etc.), which exist commercially are mostly limited to sili¬con based technologies. They are either constrained in fabricating complex geometry in micro dimension or have high operational cost. Microstereolithography (MSL) is one such rapid prototyping technique, which can satisfy the above requirements to a larger extent. MSL h8B evolved in the l8Bt decade from conventional stereolithographic (SLA) technique, which involves the free-form microfabrication of a UV sensitive liquid resin layer by layer photo-polymerization process, when it is exposed to UV irradiation accord¬ing to the predefined CAD (Computer Aided Design). However, this technique is not limited to polymer microfabrication and it h8B an immense potential to fabricate com¬plex 3D structures of ceramics in micro dimension. In this thesis, the primary focus is on developing an in house built scanning b8Bed MSL system indigenously and to explore the possibility of micro fabrication of different materials (from polymer to ceramics involving different routes. In addition, polymer micro cantilever h8B been fabricated using this technique and its application to surface stress me8Burement h8B been demonstrated. The thesis comprises of eight chapters. The following section describes the summary of the individual chapters. Chapter 1 describes the introduction and background literature of this technol¬ogy. A brief review on MSL technology developed by various research groups and their achievements h8B been listed. Since photopolymerizable resin is the primary material to fabricate micro dimensional structures, the rate of photopolymerization is an impor¬tant phenomena which requires an attention before choosing the photopolymerizable resin. Further, this chapter also describes the photoinitiation principles and the type of photo initiators (PI) which help to photopolymerize the resin in order to fabricate micro dimensional polymer structures. In addition, this chapter also gives a glimpse of applications of this technology in fabrication of micro cantilever b8Bed sensors. The later part of the chapter focused on the microfabrication of ceramic from colloidal and met¬alorganic routes in brief. In Chapter 2, the design of the in house built MSL system and its working princi¬ples including various optical issues have been addressed. Several research groups have attempted to optimize photopolymerization parameters to incre8Be the throughput of the scanning b8Bed MSL systems through modified beam scanning techniques. Efforts in reducing the curing line width in order to get low feature size have been implemented through high numerical aperture (NA) optical setups. However, the intensity contour symmetry and the depth of field of focus have led to grossly non-vertical and non-uniform curing profiles. The focus of the work h8B been to exploit the rich potential of photoreactor scanning system in achieving desired fabrication modalities (minimum curing width, uniform depth profile, and vertical curing profile) even with a reduced NA optical setup and a single movable stage. The present study tries to manipulate to its advantage the effect of optimized lower photoinitiator (PI) concentration ([c]) in reduc¬ing the minimum curing width to 10-15 jJm, even with the higher spot size (21.4 jJm) rv through a judiciously chosen gmonomer UPIi' system. In this chapter, two different cl8BS of multifunctional acrylates (1,6 Hexane diol diacrylate (HDDA) and Trimethylol propanetriacrylate (TMPTA)) and one monofunctional methacrylate (methyl mathacry¬late (MMA)) have been chosen to explore their fabricability in micro dimensions using this MSL technology, by varying the various operational parameters including the type and the concentration of the PI. Chapter 3 deals with the application of this technology in micro cantilever based sensors. Microcantilever based sensors have been explored for several decades for their application in bio-molecular or explosive detection, chemical sensing etc. Due to the adsorption of molecular species on the cantilever surface, differential surface stress gen¬erates between the top and bottom surface of the cantilever. Depending on the type of stress (tensile or compressive) generated, the cantilever bends accordingly. The, novel diffraction based deflection method has been proposed in order to measure the deflection profile accurately for low dimensional structures. To prove this method, a dual mi¬crocantilever structure with sufficiently low gap (100 f.lm) has been fabricated using the developed MSL set up, such that diffraction occurs during transillumination by spherical wavefronts. Among the two micro cantilevers one was fabricated bent with a specific di¬mension with respect to the other. The cantilever material was chosen as poly HDDA for its low elastic modulus in order to achieve high sensitivity. From the obtained diffraction pattern, the bent profile of the each cross section of one cantilever corresponding to the other has been measured. This proposition will enable to measure surface stress at each cross section of the cantilever depending on the adsorbed analyte molecule adsorption. In Chapter 4, an effort has been made to improve the thermal, thermo mechanical and mechanical properties of the cantilever material (poly HDDA). The sensitivity of a micro cantilever depends precisely on fabrication and material aspects. The former de¬pends on the aspect ratio of the structure and can be controlled by fabrication parameters whereas the latter is inherently limited by the choice of the material. The properties of the material which impact the applicability are elastic modulus, Poisson's ratio, thermal expansion and thermal stability. Hence, these properties are studied for poly HDDA. However, the properties are not completely satisfactory for only poly HDDA (PHDDA) since, PHDDA will fail for high surface stress measurement (>275 mN/m). Hence, it h8B been copolymerized with MMA with an intention to improve the above mentioned properties and to determine the best composition for the micro cantilever application. It is observed by Finite Element Analysis (FEM) that Phpm5050 (HDDA:MMA(50:50)) composition shows optimum sensitivity when reliability is concerned for me8Buring high surface stress (275 mN/m). Chapter 5 bridges Chapter 2 and Chapter 6. Chapter 2 highlights the polymer mi¬crofabrication where8B, Chapter 6 deals with the microfabrication of ceramics. In order to fabricate ceramic micro objects by MSL, ceramic particles need to be blended with a photopolymerizable monomer followed by l8Ber induced photopolymerization . Under l8Ber irradiation, the monomer gets cured and traps the ceramic particles. Thus near net shape of green ceramic structures are 0 btained. After achieving the near net shape, it is important to remove the polymer, which acts 8B the binder for the green ceramic body. This debinding should be diffusion controlled so 8B to achieve defect free micro ceramics. Here two multifunctional monomers (HDDA and TMPTA) have been chosen 8B a b8Be monomer for fabricating ceramics. Therefore it is essential to understand the debinding mechanism of these polymers. However, (HDDA) h8B high shrinkage upon polymeriza¬tion with low rate of polymerization kinetics and low viscosity where8B the properties of (TMPTA) are exactly opposite. Hence, in order to optimize these properties, copoly¬merization of HDDA and TMPTA h8B been carried out for different compositions and their thermal properties have been investigated to understand the degradation mech¬anism. This chapter deals with the mechanism of thermal degradation by model free kinetic methods with an intention to determine the optimum composition of HDDA and TMPTA copolymer, to used 8B the b8Be monomer material for ceramic microfabrication. Besides, the debinding strategy is also discussed b8Bed on the degradation profile of the optimum composition. TH20S0(TMPTA: HDDA(20:S0)) is found to be the ideal com¬position to fabricate ceramic micro-component by MSL since its degradation is diffusion controlled in N 2 atmosphere. Chapter 6 describes the methodology of microfabrication of ceramics by the de-veloped MSL technique. A colloidal approach has been adopted to fabricate ceramics in micro-dimensions. Two different ceramics have been chosen, which have potential applications in structural (alumina) and functional (Lead Iron Niobate (PFN))aspects. Before fabricating ceramic micro-objects, ceramic particles need to be blended in the monomer suspension in the presence of dispersant at an optimum solids loading. Opti¬mization of solids loading is important in view of low dimensional shrinkage after sin¬tering. However, lower loading leads to higher shrinkage whereas higher loading would increase the viscosity of the suspension and make the suspension inconvenient to deal with. Hence, rheological studies have been carried out to optimize the solids loading and dispersant concentration. 40 vol% alumina and 35 vol% PFN are found to be the highest achievable solids loading for the chosen monomer (TH2080) composition. This chapter also describes the limitation involved in ceramic microfabrication depending on their scattering factors during laser irradiation. The chapter demonstrates the fabrica¬tion methodology of several complex ceramic(alumina and PFN) micro-objects by the in house built MSL instrument. Chapter 7 investigates the possibility of microfabrication of ceramics from metalor¬ganic precursor. In this route, titanium metal-organic (Ti-n butoxide) precursor has been chosen which is stabilized by the addition of chelating monomer (2-( methacryloyloxy) ethyl acetoacetate). Following this, the crosslinker and photoinitiators have been added to form Ti photoresist which is coated on top of the bare silicon substrate by spin coating to achieve specific thickness. The coated silicon wafer by the above photoresist has been patterned by selectively exposure in the MSL setup. The cured patterns are washed and heat treated at high temperature in order to 0 btain the net shape of the Ti02 pattern of polycrystalline rutile phase. It is observed this route is advantageous in terms of reduc¬ing curing dimension (curing width 14 f.lm) than the colloidal route (curing width more than 80 f.lm ) of fabrication of ceramics where the scattering factor greatly influences the dimensions of the feature size. The key findings and future aspects are summarized in the Chapter 8. The work reported in this thesis has been carried out by the candidate as part of the Ph.D. programme. He hopes that this would constitute a worthwhile contribution towards developing an MSL technique and its aspects in micro fabrication of polymer and ceramic structures of any complex shape and its possible applications in microdevices.

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Si nanowires have potential applications in a variety of technologies such as micro and nanoelectronics, sensors, electrodes and photovoltaic applications due to their size and specific surface area. Au particle-assisted vapour-liquid-solid or VLS growth method remains the dominant process for Si nanowire growth. A comprehensive kinetic model that addresses all experimental observations and provides a physico-chemical model of the VLS growth method is thus essential. The work done as part of this research is divided into two sections. A steady state kinetic model was first developed for the steady state growth rate of Si nanowires using SiCl4 and SiH4 as precursors. The steady state refers to a balance between the rates of injection and ejection of Si into the Au droplet. This balance results in a steady state supersaturation under which wire growth proceeds. In particular evaporation and reverse reaction of Si from the Au droplet and modes of crystal growth for wire growth have been considered in detail for the first time. The model is able to account for both, the radius independent and radius dependent growth rates reported in the literature. It also shows that the radius dependence previously attributed to purely thermodynamic considerations could also as well be explained just by steady state kinetics alone. Expressions have been derived for the steady state growth rate that require the desolvation energy, activation energy for precursor dissociation and supersaturation prevalent in the particle as inputs for calculation. In order to evaluate this model the incubation and growth of Si nanowires were studied on sapphire substrates in an indigenously built automated MOCVD reactor. Sapphire was chosen as the substrate, as opposed to Si which is commonly used, so as to ensure that the vapour phase is the only source of Si. A classical incubation period for nucleation, of the order of 4-8 minutes, was experimentally observed for the first time. Using the change in this incubation period with temperature a value of 15kT was determined to be the desolvation energy for growth using SiH4. The steady state growth rate of Si nanowires were measured and compared with the predictions of the model using the values of activation energies so determined. The thesis based on the current research work is organized as follows: Chapter 1 introduces the research area followed by a brief outline of the overall work Chapter 2 provides a summary of current literature, and puts the research described in this thesis in perspective. The diameter dependent growth rate of NWs which was initially solely attributed to the Gibbs-Thomson effect is first summarized. Experimental observations to the contrary are then highlighted. These contradictions provided the incentive for the research described in this thesis. Following a summary of the growth rate theories, the experimental observations on incubation available in the literature are summarized. All the other variants of the VLS method are also discussed. Chapter 3 describes the design, construction and working of an indigenously built semi- automated CVD reactor. This CVD reactor was used to conduct the Si NW growth experiments over sapphire substrates. Chapter 4 develops the physical chemistry model for Au catalyzed Si nanowire growth using SiCl4 and SiH4 precursors. The model originated from the contradictions present in the literature over the rate limiting step of the VLS growth mechanism and the steady state growth rate dependence on wire diameter. The development starts with explaining the thermodynamics of the steady state VLS process. The significance of the model lies in the detailed analysis of the all the atomistic process occurring during the VLS growth. In particular the evaporation and reverse reaction of Si from Au-Si droplet is explained in detail and possibly for the first time. Expressions for steady state growth rate by various modes, such as layer by layer growth (LL), by multilayer growth (ML) and growth by movement of a rough interface at the L-S growth interface are derived and presented. Chapter 5 discusses the results which emerge out the kinetic model from the previous chapter. Under a single framework of equations, the model is successful in explaining both the diameter independent and diameter dependent growth of NWs. As one of the major outcomes of the model, the growth rates of Si NWs are predicted and trends in growth rate are found to agree with those experimentally observed. Growth rate dependencies on pressure and temperature are implicitly included in the equations derived. An estimate of supersaturation has been extracted for the first time using the framework of equations. Chapter 6 contains the experimental results of the Si NW growth over sapphire substrates. An incubation period in the order of 3-8 minutes has been observed for Si NW growth on sapphire. The data has been compared with existing literature data and interpreted using classical transient nucleation theory. The incubation period data has been utilized to extract the kinetic parameter, QD, which is the desolvation enegy. These parameters and the measured steady state growth rates have been used to estimate the supersaturation existing in the droplet using the framework developed in chapters 4 and 5. Chapter 7 summarizes the outcome of the current research and highlights the future directions for the research problem addressed in this thesis.

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In dieser Arbeit untersuchen wir die grundlegenden Wachstums- und Relaxationsprozesse, die es erlauben den Verzerrungszustand von GaN (0001) beim Wachstum auf Silizium (111) Substraten einzustellen und die resultierende Dichte an Durchstoßversetzungen zu reduzieren. Zu deren Analyse werden GaN (0001) Schichten, die mittels metallorganischer Gasphasenepitaxy abgeschieden worden sind, hauptsächlich mit transmissionselekronenmikroskopischen Methoden untersucht. Die wesentlichen Erkenntnisse der Arbeit sind: (i) Der Aufbau einer kompressiven Verzerrung von GaN (0001) Filmen mittels AlGaN Zwischenschichten beruht auf einer Asymmetrie der plastischen Relaxation an den beiden Grenzflächen der AlGaN Zwischenschicht. Fehlpassungsversetzungen bilden sich zwar an beiden Grenzflächen aus, jedoch ist der mittlere Abstand zwischen Versetzungslinien an der unteren Grenzfläche kleiner, als an der oberen. (ii) Plastische Relaxation von verzerrten (0001) Wurtzit Schichten erfolgt im Wesentlichen durch Bildung von a-Typ Fehlpassungsversetzungen im 1/3 |{0001} Gleitsystem. Diese bilden sich aber nur dann, wenn die verzerrten Schichten eine 3-D Morphologie aufweisen. Eine quantitative Modellierung dieses Prozesses zeigt, dass die kritische Schichtdicke für das Einsetzen der plastischen Relaxation wesentlich vom Wachstumsmodus bestimmt wird. (iii) Eine Silizium Delta-Dotierung der GaN (0001) Oberfläche führt zum Wachstum einer kohärenten Sub-Monolage SiGaN3, die eine periodisch Anordnung von Silizium- und Galliumatomen, sowie Galliumvakanzen aufweist. Da das Wachstum von GaN direkt auf der SiGaN3-Monolage unterdrückt ist, tritt ein Übergang zu 3-D Inselwachstum auf, das zunächst ausschließlich in Löchern der SiGaN3-Monolage anfängt. Eine hohe Konzentration von Silizium auf der GaN (0001) Oberfläche wirkt also als Anti-Surfactant beim epitaktischen Wachstum von GaN. Rechnungen mittels der Dichtefunktionaltheorie liefern Erklärungen für das beobachtete Wachstumsverhalten. / In this work we study the basic growth and relaxation processes that are used for strain and dislocation engineering in the growth of GaN (0001) films on silicon (111) substrates. To analyse these processes, samples, grown by metalorganic vapour phase epitaxy were investigate by means of transmission electron microscopy. Our investigations have revealed the following main results: (i) Strain engineering and build-up of compressive strain in GaN (0001) films by means of AlGaN interlayer is based on an asymmetry in plastic relaxation between the two interfaces of the AlGaN interlayer. Although misfit dislocation networks form at both interfaces of the interlayer, the average spacing of dislocation lines at the lower interface is smaller than that at the upper one. (ii) Plastic relaxation of strained (0001) wurtzite films is caused mainly by formation of a-type misfit dislocations in the 1/3 |{0001} slip-system. These a-type misfit dislocations form once the strained films undergo a transition to a 3-D surface morphology, e.g. by island growth or cracking. Quantitative modelling of this process reveals that the critical thickness for nucleation of a-type misfit dislocations depends next to the lattice mismatch mainly on the growth mode of the film. (iii) Silicon delta-doping of the GaN (0001) surface leads to the growth of a coherent sub-monolayer of SiGaN3 that shows a periodic arrangement of silicon and gallium atoms and gallium vacancies. Since growth of thick GaN layers directly on top of the SiGaN3-monolayer is inhibited a transition towards 3-D island growth occurs, whereby GaN islands exclusively nucleate at openings in the SiGaN3-monolayer. A high concentration of silicon on the GaN (0001) surface thus acts as an anti-surfactant in the epitaxial growth of GaN. Our density functional theory calculations provide an explanation for both the self-limited growth of the SiGaN3-monolayer, as well as for the blocking of GaN growth on top of the SiGaN3-monolayer.

Thin film nanostructures may be defined as assemblies, arrays, or randomly distributed nanoparticles, nanowires, or nanotubes, which together form a layer of materials supported on a substrate surface. Because such nanostructures are supported on a substrate surface, their potential applications cover a wide area in optical, magnetic, electrochemical, electromagnetic, and optoelectronic devices. The focus of the present thesis is the development of methodologies to grow certain thin film nanostructures of some transition metal oxides (TMOs), including copper oxides and LixCoO2, through CVD, sol-gel, and electromagnetic radiation-mediated approaches. The work towards this objective can be divided into three parts: first, the design, synthesis, and systematic identification of novel metalorganic precursors of copper (monometallic) and Li and Co (bimetallic); second, the growth of nanostructured oxides thin films using these precursors; and third, the application of electromagnetic radiation to control or tailor the growth of as grown nanostructures. The underlying growth mechanisms substantiated by appropriate evidence have been put forward, wherever found relevant and intriguing. It may be added that the principal objective of the work reported here has been to explore the several ideas noted above and examine possibilities, rather than to study any specific one of them in significant detail. It is hoped earnestly that this has been accomplished to a reasonable extent. Chapter 1 reviews briefly the reports available in the literature on three specific methods of growing thin films nanostructures, namely chemical vapour deposition, sol-gel processing and light-induced approach. The objective of this chapter has been to provide the background of the work done in the thesis, and is substantiated with a number of illustrative examples. Some of the fundamental concepts involved, viz., plasmons and excitons, have been defined with illustration wherever found relevant in the context of the work. Chapter 2 describes the various techniques used for synthesis and characterisation of the metalorganic complexes as well as of the thin films. This chapters covers mostly experimental details, with brief descriptions of the working principles of the analytical procedures adopted, namely, infrared spectroscopy, mass spectroscopy, elemental analysis, and thermal analysis for characterisation of the metalorganic complexes. This is followed by a similarly brief account of techniques employed to characterize the thin films prepared in this work, viz., glancing incidence X-ray diffraction (GIXRD), field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), electrostatic force microscopy (EFM), transmission electron microscopy (TEM), glancing incidence infra-red spectroscopy (GIIR) and, UV-visible spectroscopy. The metalorganic chemical vapour deposition (MOCVD) systems built in house and used for growth of films are described in detail. The topics in the different sections of the chapter are accompanied by pertinent diagrams. Chapter 3 deals with the design, synthesis and characterisation of novel polynuclear complexes of copper and cobalt. Keeping in mind the various advantages such as low toxicity, ease of synthesis, non-pyrophoricity, and low temperature volatility, of environmentally benign complexes based on biologically compatible such as triethanolamine, diethanolamine, the objective has been to synthesize complexes containing triethanolamine and diethanolamine of transition metals such as cobalt and copper, and to investigate their applicability in MOCVD processes as a novel class of precursors. With the notion of ‘better’ and efficient design of precursors, an attempt has been made, through a semi-empirical modeling, to understand the correlation between volatility and various intrinsic molecular parameters such as lattice energy, vibrational-rotational energy, and internal symmetry. Chapter 4 discusses the growth of nanoporous Cu4O3-C composite films through the MOCVD process employing Cu4(deaH)(dea)(oAc)5.(CH3)2CO as the precursor. The various characteristic aspects of as-grown films, such as their crystallinity, morphology, and composition have been covered elaborately in various sections of this chapter. The chapter describes the efficient guiding and confining of light exploiting the photonic band gap of these nanoporous films, which indicates the potential usefulness of these and similar films as optical waveguides. A model described in the literature on absorbing photonic crystals, wherein a periodically modulated absorption entails an inevitable spatial modulation of dispersion, i.e., of the index contrast to open a photonic band gap, has been used to calculate the indices of refraction of one of these nanoporous films. The chapter also reports briefly the preliminary electrochemical investigations carried out on a typical film, examining the notion of its application as the anode in a Li-ion rechargeable battery. Chapter 5 describes the synthesis of nanocrystalline LixCoO2 films by the sol-gel method. Reports available in literature indicate that the various phases of LixCoO2 are extremely sensitive to processing temperature, making it difficult to control dimensionality of a given phase using temperature as one of process parameters. We have investigated the possibility of using incoherent light to tailor the particle size/shape of this material. The as-grown and irradiated films were characterised by X-ray diffraction, and by microscopic and spectroscopic techniques.Optical spectroscopy was carried out in order to gain insight into the physico-chemical mechanism involved in such structural and morphological transformation. Chapter 6 deals with the synthesis of self-assembled nanostructures from the pre-synthesized nanocrystals building blocks, through optical means of exciton formation and dissociation. It has been demonstrated that, upon prolonged exposure to (incoherent) ultraviolet-visible radiation, LixCoO2 nanocrystals self-assemble into acicular architectures, through intermediate excitation of excitons. Furthermore, it has been shown that such self-assembly occurs in nanocrystals, which are initially anchored to the substrate surface such as that of fused quartz. This new type of process for the self-assembly of nanocrystals, which is driven by light has been investigated by available microscopic and spectroscopic techniques. Chapter 7 describes the stabilisation of chemically reactive metallic lithium in a carbonaceous nanostructure, viz., a carbon nanotube, achieved through the MOCVD process involving a lithium-alkyl moiety. This moiety is formed in situ during deposition through partial decomposition of a metalorganic precursor synthesized in house, which contains both lithium and cobalt. It is surmised that the stabilization of metallic Li in the nanostructure in situ occurs through the partial decomposition of the metalorganic precursor. Quantitative X-ray photoelectron spectroscopy carried out on such a film reveals that as much as 33.4% metallic lithium is trapped in carbon. Lastly, Chapter 8 briefly highlights the outlook for further investigations suggested by the work undertaken for this thesis. Novel precursors derived from biologically compatible ligands can open up possibility of growing new type of micro/nano-structures, and of unusual phases in the CVD grown films. Furthermore, it is proposed that the novel method of growth and alignment of nanocrystals through irradiation with incoherent light, employed for the specific material LixCoO2, may be employed for various other metallic and semiconducting materials.

Zusammenfassung: Die vorliegende Arbeit lässt sich thematisch in drei Bereiche gliedern. Der erste Teil handelt von der Synthese stark elektronenziehender Ligandensysteme und deren Umsetzung zu Metallocendichloriden. Es zeigt sich, dass die Umsetzung von pentafluorbenzolhaltigem Cyclopentadien, Inden oder Fluoren mit Silizium-Verbindungen nicht zu der gewünschten Reaktion zu Si-verbrücken Systemen führen, sondern, dass sich andersartige Si-F-Moleküle bilden. Zugängliche, unverbrückte Komplexe zeigen im besonderen eine geringe Stabilität im Vergleich zu ’nicht-C6F5-haltigen’ Metallocenen. Die Hauptthematik der Arbeit beschäftigt sich mit der Synthese von in 2-Position funktionalisierter sowie verbrückter Indene und deren Umsetzung zu Metallocenkomplexen. Hierbei interessiert vor allem der sterische Einfluss der am Ligandensystem sitzenden Gruppen. Die Darstellung der Inden-2-verbrückten Indene erstreckt sich über eine Bromaddition, thermodynamische Freisetzung von HBr, Grignard-Reaktion und anschließender Brückenbildung mit Cyclopentadien- und tert.Butylamineinheiten. Weiterer Bestandteil dieses Abschnitts ist die Umsetzung der synthetisierten Moleküle zu Metallocenverbindungen. Dabei werden auf diesem Wege Sandwich- bzw. Halbsandwich-Komplexe in guter Ausbeute erhalten. Der dritte Bereich beschäftigt sich mit der Umsetzung von Titan-4-chlorid gegenüber unterschiedlichern Trimethylsilyl-substituierten Indenen. Durch Substitution eines Chloratoms durch eine Phenolatgruppe erhält man die Indenyldichlortitanphenolate.

Ein großes Hindernis für die Anwendbarkeit von oxidischen Perowskiten in elektrotechnischen oder spintronischen Applikationen, ist die Größe der spezifischen Temperaturen, bei der die physikalischen Phänomene, wie Ferromagnetismus oder Hochtemperatur-Supraleitung, beobachtet werden können. Die physikalischen Eigenschaften der Perowskite zeigen eine Abhängigkeit von der Ordnung der verschiedenartigen Metallionen in mehrkomponentigen Systemen. Die Abhängigkeit ergibt sich durch den Einfluss der Metallionen auf die Elektronenkonfiguration und elastischen Verspannung innerhalb des Materials. Man spricht in diesem Zusammenhang auch von der Kontrolle der Füllung und der Bandbreite der elektronischen Bänder im Material durch die Wahl der Metallionen. Die Zielsetzung dieser Arbeit ist die Präparation und Charakterisierung von künstlich A-Platz geordneten schmal- und breitbandigen Manganat Dünnfilmen als auch von natürlich B-Platz geordneten ferro-/ferrimagnetischen doppelperowskitischen Dünnfilmen. Für die Präparation der dünnen Schichten wurde die unkonventionelle Metallorganischen Aerosol Deposition (MAD) verwendet. Es konnte gezeigt werden, dass diverse künstlich oder natürlich Kationengeordnete Perowskite mit der MAD Technologie präpariert werden können. Die lagenweise A-Platz Ordnung in Manganaten führt, über die Modulation der Gitterverspannung und der Elektronenbesetzung im eg-Band der Manganionen, zu modifizierten elektronischen und magnetischen Eigenschaften. In schmalbandigen CMR Manganaten wurde die PS und somit der CMR über die Ordnung beeinflusst, während in breitbandigen CMR Manganaten ein Weg aufgezeigt werden konnte, der zu Übergangstemperaturen TC > 370K führen kann. In geordneten, ferromagnetischen Doppelperowskiten wurde der Einfluss und die Anwesenheit von Antiphasen-Grenzen dargelegt. Über die Einführung einer aktiven Valenz-Kontrolle, konnte die Präparation von halbmetallischen, ferrimagnetischen Doppelperowskiten mit der MAD Technologie ermöglicht werden.

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