<p>Heteroepitaxial SiGeC layers have attracted immenseattention as a material for high frequency devices duringrecent years. The unique properties of integrating carbon inSiGe are the additional freedom for strain and bandgapengineering as well as allowing more aggressive device designdue to the potential for increased thermal budget duringprocessing. This work presents different issues on epitaxialgrowth, defect density, dopant incorporation and electricalproperties of SiGeC epitaxial layers, intended for variousdevice applications.</p><p>Non-selective and selective epitaxial growth of Si_1-x-yGe_xC_y(0≤x≤30, ≤y≤0.02) layershave been optimized by using high-resolution x-ray reciprocallattice mapping. The incorporation of carbon into the SiGematrix was shown to be strongly sensitive to the growthparameters. As a consequence, a much smaller epitaxial processwindow compared to SiGe epitaxy was obtained. Differentsolutions to decrease the substrate pattern dependency (loadingeffect) of SiGeC growth have also been proposed. The key pointin these methods is based on reduction of surface migration ofthe adsorbed species on the oxide. In non-selective epitaxy,this was achieved by introducing a thin silicon polycrystallineseed layer on the oxide. The thickness of this seed layer had acrucial role on both the global and local loading effect, andon the epitaxial quality. Meanwhile, in selective epitaxy,polycrystalline stripes introduced around the oxide openingsact as migration barriers and reduce the loading effecteffectively. Chemical mechanical polishing (CMP) was performedto remove the polycrystalline stripes on the oxide.</p><p>Incorporation and electrical properties of boron-doped Si_1-x-yGe_xC_ylayers (x=0.23 and 0.28 with y=0 and 0.005) with aboron concentration in the range of 3x10¹⁸-1x10²¹atoms/cm3 have also been investigated. In SiGeClayers, the active boron concentration was obtained from thestrain compensation. It was also found that the boron atomshave a tendency to locate at substitutional sites morepreferentially compared to carbon. These findings led to anestimation of the Hall scattering factor of the SiGeC layers,which showed good agreement with theoretical calculations.</p><p><b>Keywords:</b>Silicon germanium carbon (SiGeC), Epitaxy,Chemical vapor deposition (CVD), Loading effect, Highresolution x-ray diffraction (HRXRD), Hall measurements, Atomicforce microscopy (AFM).</p>

No description available.

Electrically conductive or electro-active fibers are the key components of smart and interactive textiles, which could be used in medical, sports, energy, and military applications in the near future. The functionalization of high-performance textile yarns/fibers with conjugated polymers can produce conductive fibers with better electro-mechanical properties, which is difficult with commonly used spinning techniques. In this thesis work, textile-based conductive yarns/fibers were prepared by coating viscose and polyester (PET) yarns with the conjugated polymer PEDOT. For coating purposes, an efficient technique called chemical vapor deposition (CVD) was used, which is a solventless technique and can produce PEDOT polymer layers with high conductivity values. The polymerization of EDOT monomer vapors and coating of oxidant (FeCl3 or FepTS) enriched viscose and PET yarns took place simultaneously. The PEDOT-coated viscose and polyester yarns showed relatively high conductivity values, which could be sufficient for many electronic applications. The polymerization process and the quality of PEDOT polymer strongly depends on different reaction conditions. In this research work, the impact of most of these reaction parameters on the electrical, mechanical, and thermal properties of PEDOT-coated conductive yarns was considered separately. Under specific reaction conditions, it was found that viscose fibers were successfully coated with PEDOT polymer and showed rather high electrical conductivity (≥ 15 S/cm). However, due to the acid hydrolysis of viscose fibers in FeCl3 solutions, the mechanical properties were drastically reduced. In order to improve the mechanical properties of conductive yarns, a relatively stable and chemical-resistant substrate (PET) was coated with PEDOT polymer. Comparative studies between PEDOT-coated viscose and PET conductive yarns showed that the electrical and mechanical properties were enhanced by changing the substrate material. Later on, PEDOT-coated conductive fibers were treated with silicone elastomer solution and due to the thin silicone layers, the hydrophobic properties, flexibility, and durability of coated yarns was improved. Furthermore, a novel electrical resistance-measuring setup was developed, which can be used not only for fibers but also for fabric structures. The electrical characterization of PEDOT-coated conductive yarns showed that it can be used effectively for sensitive fibers without damaging their surface morphology. Finally, the use of conductive yarns as stretch sensors was evaluated. For this purpose, small rectangular knitted patches of conductive yarns were prepared and then the change in electrical resistance values at different extension percentages (5–50%) was investigated. The constant variations in electrical resistance values at different extension and relaxation cycles for longer periods of time revealed that the conductive yarns produced have the potential to be used as stretch sensors for monitoring of vital signs in medical and sports applications. / <p>Thesis for the Degree of Doctor of Philosophy to be presented on March 08, 2013, 10.00 in KA-salen, Kemigården 4, Chalmers University of Technology, Gothenburg</p>

Abstract Carbon nanotubes (CNTs) are known for their excellent mechanical, electrical and thermal properties, that have fostered a vast number of applications during the last two decades, from composites, electrodes and nanoelectonics components, to sensors and biological scaffolds. Direct integration of CNTs into devices is not straightforward, as high growth temperatures (above 600 °C) challenge the chemical and thermal stability of substrates, catalysts and other nearby materials or components. However, by decreasing growth temperature and/or working out protocols that take into account the thermal stability of the materials involved, it is possible to create several new types of architectures and devices with functionalities not shown before. In this work, we show that, with selection of the appropriate substrate, diffusion barrier and catalyst materials, direct growth of functional CNT films and their micropatterns may be achieved, not only on Si chips, but also on other atypical surfaces, using chemical vapor deposition. This thesis explores low-temperature CNT synthesis over bi- and trimetallic catalysts, and investigates the effect of diffusion barrier layers on the electrical properties of substrate-to-CNT contacts. On one hand, the lowest achieved CNT synthesis temperature (400 °C) is compatible with most silicon technologies, thus enabling direct integration of CNTs with materials and devices with low thermal budgets. On the other hand, the results of diffusion barrier studies helped us in designing and demonstrating on-chip micropatterned CNT structures for super and pseudocapacitor electrodes. In addition, we also show a method for maskless growth of CNT micropatterns using laser-treated steel and superalloy surfaces, whose surface diffusion properties change as a result of barrier-type metal oxide formation. Furthermore, we present CNT growth on carbon materials and demonstrate entirely carbon-based hierarchical composites for electromagnetic interference shielding applications, exhibiting outstanding absorption-based shielding performance. The results presented in this thesis are expected to contribute to a further expansion of CNT-based technologies, in particular with potential for future advances in high-frequency devices (arrays, amplifiers and shielding materials), energy materials (electrodes and scaffolds), as well as in nanoelectromechanical systems (sensors and actuators). / Tiivistelmä Hiilinanoputket tunnetaan niiden erinomaisista mekaanisista, sähköisistä ja termisistä ominaisuuksista, joita on hyödynnetty lukuisissa sovelluksissa viimeisen kahden vuosikymmenen aikana alkaen komposiiteista, elektrodeista, nanoelektroniikkakomponenteista ja sensoreista aina biologisiin tukirakenteisiin. Nanoputkien synteesi suoraan laitteessa ei ole suoraviivaista, sillä korkeat, yli 600 °C synteesilämpötilat asettavat haasteita substraatin, katalyytin sekä muiden lähellä olevien materiaalien ja komponenttien kemialliselle ja termiselle vakaudelle. Alentamalla synteesilämpötilaa ja/tai kehittämällä termisen vakauden huomioivia menetelmiä on mahdollista luoda uudenlaisia arkkitehtuureja ja sovelluksia ennennäkemättömillä ominaisuuksilla. Tässä työssä osoitetaan, että sopivan substraatin, diffuusiosuojan ja katalyyttimateriaalin valitsemalla funktionaalisten hiilinanoputkien synteesi on mahdollista piin lisäksi myös muille, epätavallisille pinnoille käyttäen kemiallista kaasufaasipinnoitusta. Väitöstyössä käsitellään hiilinanoputkien matalan lämpötilan synteesiä hyödyntäen kaksi- ja kolmimetallisia katalyyttejä sekä tutkitaan diffuusiosuojakerroksen sähköistä vaikutusta substraatin ja hiilinanoputkien väliseen kontaktiin. Alin saavutettu synteesilämpötila (400 °C) on yhteensopiva useimpien piiteknologioiden kanssa, mikä mahdollistaa nanoputkien suoran integroinnin matalaa lämpötilaa edellyttäville materiaaleille. Työssä tutkitun diffuusiosuojakerroksen kehitys mahdollisti myös piisirun päälle toteutettujen hiilinanoputkipohjaisten super- ja pseudokondensaattorielektrodien demonstroinnin. Lisäksi työssä esitetään menetelmä, jossa laserkäsittelemällä teräs- ja supermetalliseospinta, jonka avulla mikrokuvioitu hiilinanoputkien kasvu ilman litografiaprosessia on mahdollista. Viimeisenä työssä esitetään hiilinanoputkien synteesi suoraan toiselle hiilimateriaalille ja demonstroidaan täysin hiilipohjainen, hierarkkinen komposiittimateriaali erinomaisella absorptioon perustuvalla suojauskyvyllä sähkömagneettisiin häiriösuojaussovelluksiin. Väitöstyössä esitettyjen tulosten odotetaan osaltaan edistävän hiilinanoputkipohjaisten teknologioiden kehitystä erityisesti korkean taajuuden laitteissa, energiamateriaaleissa sekä nanosähkömekaanisissa järjestelmissä.

A miniaturização de uma biocélula a combustível (BC) enzimática de glicose/O2 para aplicação em dispositivos bioeletrônicos implantáveis representa um grande desafio em eletroquímica moderna. Isso porque é preciso desenvolver bioeletrodos com alta atividade bioeletrocatalítica, com enzimas fortemente ligadas a superfície eletródica. Além disso, o próprio processo de micromanipulação é desafiador, uma vez que é desejável obter biocélulas miniaturizadas e com alta densidade de potência. Assim, propõe-se aqui o desenvolvimento de uma BC que atenda os requisitos supracitados. Para isso, desenvolveram-se bioânodos e biocátodos compostos por folhas de grafeno individuais modificadas com as enzimas glicose desidrogenase (GDh) e bilirrubina oxidase (BOx), respectivamente. Eletrodos de grafeno com área de 10-3 cm2 e espessura de 0,9 ± 0,2 nm foram utilizados em um microchip de Si/SiO2. Observou-se que o grafeno transferido para o microchip permanecia com contaminações de cobre, mesmo após a utilização dos métodos químicos tradicionais de remoção desse metal. A presença de cobre é decorrente do processo de fabricação do grafeno, neste caso, a deposição química em fase vapor (CVD). Para remover qualquer resíduo deste metal, submeteu-se o grafeno a um procedimento de remoção eletroquímica de cobre, denominada aqui como e-etching. Uma vez não observada qualquer corrente faradaica residual associada às impurezas, obtiveram-se os bioeletrodos com a GDh e a BOx. Para a imobilização enzimática, utilizou-se a ligação covalente via funcionalização com o ácido 4-aminobenzóico. As curvas de polarização de estado quase-estacionário obtidas com os bioeletrodos em tampão fosfato pH 7,0 revelaram correntes de onset para oxidação de glicose em -0,13 V e redução de oxigênio em 0,45 V. Por fim, os eletrodos foram utilizados em uma BC sem membrana, operando no microchip de Si/SiO2, em eletrólito tampão fosfato saturado com O2 e glicose 8,0 mmol L-1. A BC apresentou um potencial de circuito aberto em 0,55 V, com densidade de potência volumétrica igual a 1,7 W cm-3, o maior valor reportado até os dias de hoje para uma BC. / The miniaturization of a glucose/O2 enzymatic biofuel cell (BFC) for application in implantable bioelectronic devices is a challenge in electrochemistry. For this purpose, the necessity of bioelectrodes development with high biocatalytic activity such as enzymes strongly attached to electrode surfaces is a current trend. Moreover, the micromanipulation procedure itself is a challenge since the obtention of BFCs with high power density is desirable. Then, the present study shows the partial results obtained in the development of a glucose/O2 BFC with the characteristics exemplified. For the later, bioanodes and biocathodes were obtained with single graphene flakes modified with the enzymes glucose dehydrogenase (GDh) and bilirubin oxidase (BOx), respectively. Graphene flakes electrodes with area of about 10-3 cm2 and thickness of 0,9 ± 0,2 nm were used in a Si/SiO2 microchip. It was observed that transferred graphene to the microchip remained with copper/copper oxide contamination even after the use of conventional methodologies for the remotion of the metal from single graphene foils. The presence of the remaining copper is due to the fabrication process of graphene by chemical vapor deposition (CVD). For the remotion of remaining impurities from graphene, the electrochemical remotion of copper from graphene was carried out in acidic media by the so called e-etching procedure. Since no residual faradaic current was observed due to metal/metal oxide impurities in graphene electrodes, the bioelectrodes were obtained with the enzymes GDh and BOx. The covalent functionalisation of graphene with 4-aminobenzoic acid via diazonium coupling reaction was used for the enzymatic immobilization. The quasi-stationary polarization curves obtained with the bioelectrodes in phosphate buffer pH = 7,0 showed onset oxidation current for glucose at -0.13V and reduction of molecular oxygen starting at +0.45V. Finally, the bioelectrodes were used in a membraneless BFC operating in a Si/SiO2 microchip under saturated oxygen and glucose 8 mmol L-1 in the electrolyte media. The BFC showed an open circuit potential at 0.55V and volumetric power density of 1.7 W cm-3, the highest value reported for an enzymatic BFC so far.

Neste trabalho é apresentada a simulação, fabricação e caracterização de filtros interferenciais empregando películas dielétricas amorfas depositadas pela técnica de deposição a vapor assistida por plasma (PECVD) sobre substratos de silício e de Corning Glass (7059). Os dispositivos ópticos foram construídos usando-se processos padrões de microeletrônica e consistiram em camadas periódicas com espessura e índice de refração apropriados para produzir picos da atenuação na transmitância da luz na região visível. Simulações numéricas precedentes foram realizadas baseando-se nas características ópticas das películas dielétricas. Para a caracterização dos filtros interferenciais, uma luz monocromática de um laser de He-Ne, foi injetada nos filtros e a luz obtida na saída foi conduzida então a um detector. O filtro depositado sobre Corning Glass (chamado de filtro vertical) e o filtro depositado sobre silício com cavidades (chamado de filtro suspenso) foram montados sobre dispositivos térmicos e angulares de modo a medir suas respostas à variação angular e térmica. Também, o filtro depositado sobre silício (chamado de filtro horizontal) foi montado sobre um dispositivo térmico, a fim de medir sua resposta à temperatura. Quando os filtros são submetidos a uma mudança na temperatura, uma variação do índice de refração devido ao efeito termo-óptico produz um deslocamento nos picos da atenuação, que podem ser previstos por simulações numéricas. Esta característica permite que estes dispositivos sejam usados como sensores termo-ópticos. Por outro lado, quando o filtro vertical e o filtro suspenso são submetidos a variações angulares entre a normal ao plano do filtro e o feixe de laser, uma variação na potência da luz de saída é produzida. Esta característica permite que estes dispositivos sejam usados como sensores angulares. / In this work, we present the simulation, fabrication and characterization of filters employing amorphous dielectric films deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) technique on crystalline silicon and Corning Glass (7059) substrates. The optical devices were fabricated using standard microelectronic processes and consisted of periodic layers with appropriated thickness and refractive indexes to produce transmittance attenuation peaks in the visible region. For this, previous numerical simulations were realized based in the optical parameters of the dielectric films. For the characterization of the optical interferential filters, a monochromatic light, a He-Ne laser, was projected onto the filters and the transmitted output light was then conducted to a detector. The optical filters were produced on Corning Glass (here called vertical filter) and on silicon substrates. The silicon substrate was etch in KOH solution to form cavities and suspend part of the filter (here called suspended filter). The vertical and suspended filters were mounted on thermo and angular devices that allowed the measurement of the optical power as a function of temperature and angle changes. A second type of filter deposited over a silicon substrate (here called horizontal filter) was mounted on thermoelectric device, in order to control the temperature responses. When the filters are submitted to a change in temperature, a variation of the refractive index is originated in the dielectric film due to the thermo-optic effect (TOE), producing a shift in the attenuation peaks, which can be well predicted by numerical simulations. This characteristic allows these devices to be used as thermo-optic sensors. On the other hand, when the vertical filter and the suspended filter were subjected to an angular shift between the filter\'s normal and the laser, a variation of the output optical power is originated. This characteristic allows these devices to be used as angular sensors.

De par leurs propriétés remarquables, les nanotubes de carbone (NTCs) reçoivent beaucoup d’attention et de nombreuses recherches sont menées sur ces matériaux depuis les dernières décennies. Le nombre d'applications envisagées mais aussi la quantité demandée de NTCs augmentent chaque année. Pour atteindre une production à grande échelle et contrôlée, il est nécessaire d'avoir une bonne compréhension des mécanismes de croissance des NTCs. Dans ce manuscrit, la formation ainsi que l'activité catalytique de nanoparticules (NPs) par dépôt chimique en phase vapeur assisté par aérosol (CVD) sont étudiées expérimentalement, pour analyser le processus d'évolution des NPs et leur relation avec les NTCs.Dans le chapitre 1, nous présentons une introduction générale sur des structures, les méthodes de synthèse, les propriétés et les applications envisagées des NTCs, ainsi que l’état de l’art concernant l’étude des mécanismes de croissance des NTCs.Dans le chapitre 2, nous décrivons le système de dépôt chimique en phase vapeur avec catalyseur flottant, ainsi que les méthodes de diagnostic in-situ/ex-situ utilisées dans cette étude. La technique d’incandescence induite par laser (LII) est particulièrement importante dans ce chapitre, car cette technique nous permet de réaliser un diagnostic in situ sur la quantité/taille des NPs déposées pendant le processus de synthèse.Dans le chapitre 3, nous présentons l'évolution des NPs lors de la synthèse ainsi que les influences des différents paramètres de CVD (température, quantité de carbone/catalyseur, composition du gaz, etc.) sur les gouttelettes et les NPs respectivement. Un modèle pour la formation de NPs est proposé à la fin de ce chapitre.Dans le chapitre 4, les résultats des expériences sur l'évolution de la composition du gaz sont révélés. Ces résultats donnent des informations concernant les réactions chimiques ayant lieu dans la phase gazeuse lors de la synthèse des NTCs.Dans le chapitre 5, une étude détaillée de l'influence des paramètres de CVD sur les produits NTCs est menée, et les relations entre les NPs et les NTC sont discutées.Pour finir, des conclusions générales ainsi que les perspectives prévues pour les travaux futurs sont présentées. / Due to the outstanding properties in various aspects, carbon nanotubes (CNTs) received worldwide attentions and intensive investigations are carried out in the last decades. While the number of applications as well as the quantity demanded of CNTs are increasing year after year, to achieve large scale production of the desired structures in a controlled way, it is highly required having a clear understanding about the CNTs growth mechanism. In this study, the formation and catalytic activity of nanoparticles (NPs) under aerosol-assisted chemical vapor deposition (CVD) is experimentally investigated, aiming to study the NPs evolution process and their relation with the CNTs products.In chapter 1, we provide a general review of CNTs structures, synthesis methods, properties as well as applications. Moreover, the current situation of CNTs growth mechanism study is presented.In chapter 2, the floating catalyst chemical vapor deposition synthesis system, and the in-situ/ex-situ diagnostic methods used in this study are introduced. Laser induced incandescence technique (LII) is particularly explained in this chapter, which permits to achieve an in-situ diagnostic of the NPs quantity/size during the synthesis process.In chapter 3, the evolution of NPs during the synthesis is presented, in which the influences of different CVD parameters (temperature, carbon/catalyst quantity, gas composition etc.) on the droplets as well as on the NPs are investigated respectively. A NPs formation model is proposed based on the NPs variation information at the end of this chapter.In chapter 4, the experimental results of the gas composition evolution in chemical vapor deposition reactor are revealed, which reflect the gas phase chemical reactions information during the CNTs synthesis.In chapter 5, a detailed investigation about the influence of CVD parameters on the CNTs products is explained. And the relation between the NPs and CNTs is discussed.In the end, general conclusions are formed according to works and perspectives are provided for the improvement of the future work.

Dans les technologies avancées, l’épitaxie des matériaux à base de silicium devient de plus en plus critique et les effets morphologiques importants. Les traitements thermiques ainsi que le dopage peuvent altérer la morphologie des épitaxies dégradant de façon considérable les performances des dispositifs. Les travaux de thèse ont pour objectifs de comprendre et résoudre ces problématiques, ils concernent donc l’étude de la morphologie et des forts dopages des épitaxies dans les motifs de petites tailles des technologies CMOS 14 et 10 nm. Nous avons étudié l’influence des conditions de recuit sous H2 sur la morphologie des épitaxies. Ceci a conduit à la détermination de la cinétique d’arrondissement thermique dans les petits motifs (100 nm et moins). D’après une analyse de la cinétique, deux énergies ont été identifiées : 2,9 eV et 7,7 eV. L’énergie de 2,9 eV montre qu’aux hautes températures, la diffusion de surface est le principal mécanisme de l’arrondissement thermique. Aux faibles températures, l’augmentation de la couverture d’hydrogène limite encore plus cette diffusion, augmentant fortement l’énergie obtenue. Nous avons observé que la pression du gaz porteur et la nature de celui-ci ont un impact important sur la diffusion de surface et modulent donc la cinétique d’arrondissement thermique. La caractérisation par microscopie à force atomique de croissances sélectives de couches SiGe dopées bore, montre que le bore modifie grandement la morphologie de croissance, ainsi que l’arrondissement thermique. Pour un même recuit, un motif dopé s’arrondit beaucoup plus rapidement qu’un motif non dopé. Les épitaxies développées au cours de ces travaux ont été intégrées avec succès dans les sources/drains du CMOS 14 nm. Selon le besoin, les épitaxies peuvent soit présenter de larges facettes bien définies soit aucune facette, et cela grâce à un procédé adéquat que ce travail a permis de proposer et développer / In advanced technologies, the Si-based materials epitaxy becomes more and more challenging and the morphological effects very important. The thermal treatments as well as the doping may degrade the epitaxies’ morphology resulting in considerably damaging the devices’ performances. The works presented in this thesis, aim at understanding and solving these problematics. Thus, they are focused on the study of the epitaxies’ morphology and high doping in the small patterns of the 10 and 14 nm CMOS technologies. The influence of the H2 annealing conditions on the morphology was studied. This led to determine the thermal rounding kinetics in small patterns. According to a kinetics analysis, two energies were identified: 2.9 eV and 7.7 eV. The 2.9 eV energy shows that at high temperatures, the surface diffusion is the thermal rounding main mechanism. At low temperatures, the hydrogen coverage’s increase limits even more this diffusion, greatly increasing the energy obtained. It was observed that the carrier gas pressure and its nature have a strong impact on the surface diffusion and thus modify the thermal rounding kinetics. The characterization by atomic force microscopy, of boron doped layer selectively grown, shows that the boron greatly modifies the growth’s morphology, as well as the thermal rounding. Considering a same annealing, the rounding phenomenon occurs faster in a doped pattern than in an un-doped pattern. The epitaxies developed during this work were successfully integrated to the 14 nm node sources and drains. Depending on the needs, the epitaxies can either present large and well defined facets or no facets, all of this thanks to an adequate process which was proposed and developed through this work.

<p>This thesis is based on experimental studies in chemical physics. Titanium dioxide (TiO₂) and phthalocyanine’s (Pc’s), interesting in many future perspectives, have been deposited as thin films and studied as follows. Information has been obtained on e.g. molecular orientation, crystal structure, depth profile of the chemical composition, electrochemical properties and electronic structure. This has been achieved by means of a combination of techniques: X-ray photoelectron spectroscopy (XPS), near edge x-ray absorption fine structure (NEXAFS), density functional theory calculations (DFT), UV-visible absorption spectroscopy (UVVIS) and cyclic voltammetry (CV).</p><p>Metal-free phthalcyanine (H₂Pc) has been shown to form films with different crystal structure and molecular orientation depending on deposition method, evaporation/sublimation or powder deposition, on commercial conducting glass (fluorine doped tin oxide, FTO), which is used e.g. in solar cells and organic light emitting devices (OLEDs). The unoccupied molecular orbitals are divided in x, y and z space coordinates of the molecule and also divided in inequivalent nitrogen components. </p><p>The electronic structure is also studied for a sublimated titanyl phthalocyanine (TiOPc) film and related to the metal-free phthalocyanine. The ligand field around the titanium atom in TiOPc is compared with that of TiO₂ to delineate the unoccupied levels recorded by means of x-ray absorption spectroscopy.</p><p>Nanostructured TiO₂ films were manufactured by screen printing/doctor blading on FTO. Such films were additionally covered with lutetium diphthalocyanine (LuPc₂) by means of surface assembly from solution. LuPc₂^-, LuPc₂⁺ and LuPc₂H were identified and the stability of the electrochromic reactions in this system was monitored.</p><p>Chemical vapor deposition (CVD) has been used to grow nanometer sized anatase TiO₂ crystals on pre-oxidized Si (111) without formation of interfacial carbon and with an interface layer of the size of 15- 25Å. The interface layer was found to be amorphous TiSi_xO_y with graded stoichiometry. </p>

In the growing field of spintronics there is a strong need for development of flexible lightweight semi-conducting magnets. Molecular organic-based magnets are attractive candidates since it is possible to tune their properties by organic chemistry, making them so-called “designer magnets”. Vanadium tetracyanoethylene, V(TCNE)x, is particularly interesting since it is a semiconductor with Curie temperature above room temperature (TC~400 K). The main problem with these organic-based magnets is that they are extremely air sensitive. This thesis reports on the frontier electronic structure of the V(TCNE)x by characterization with photoelectron spectroscopy (PES) and near edge x-ray absorption fine structure (NEXAFS) spectroscopy. It also presents a new and more flexible preparation method of this class of organic-based thin film magnets. The result shows improved air stability of the V(TCNE)x prepared with this method as compared to V(TCNE)x prepared by hitherto used methods.