• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 63
  • 23
  • 9
  • 7
  • 6
  • 6
  • 5
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 147
  • 27
  • 25
  • 24
  • 23
  • 20
  • 18
  • 18
  • 15
  • 12
  • 11
  • 11
  • 10
  • 10
  • 9
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Porous Metal Oxides and Their Applications

Tien, Wei-Chen 15 July 2012 (has links)
Porous metal oxides formed by supercritical carbon dioxide (SCCO2) treatments at low temperature were used for displays, solar cells, and light emitting diodes (LEDs) applications. The SCCO2 fluid, also known as green solvents, exhibits low viscosity, low surface tension and high diffusivity as gases, and high density and solubility same with liquids. In this thesis, we successfully fabricated porous antimony-doped tin oxide (ATO) and porous indium tin oxide (ITO) by the SCCO2 treatments. In addition, the treatment can also be used to improve the work function and surface energy of ITO anode of an organic LED (OLED). The performance of the OLEDs was drastically enhanced in comparison with that of the devices without any ITO surface treatments. First, the porous ATO films were formed by the SCCO2 treatment for absorption of silver molecules in silver electro deposition devices. The porosity, resistivity and average optical transmittance of the porous ATO film in visible wavelength were 43.1%, 3 £[-cm and 90.4%, respectively. For the silver electro deposition devices with the porous ATO film, the transmittance contrast ratio of larger than 12 in visible spectrum was obtained at an operating voltage of 1.5 V. Furthermore, for the 0.25 cm2 device, the switching time of 4.5 seconds was achieved by applying a square-wave voltage ranging from 1.5 to -0.2 V between the electrodes. On the other hand, the porous ITO with low refractive index was prepared by SCCO2/IPA treatment on gel-coated ITO thin films. The high refractive index of the ITO film was achieved by long-throw radio-frequency magnetron sputtering technique at room temperature. The index contrast (£Gn) was higher than 0.6 between porous ITO and sputtered ITO films. The large £Gn is useful for fabricating conductive anti-reflection (AR) and high reflection (HR) structures using the porous ITO on sputtered ITO bilayers. The weighted average reflectance and transmittance of 4.3% and 83.1% were achieved for the double-layer ITO AR electrode with a sheet resistance of 1.1 K£[/¡E. For HR structures, the reflectance and sheet resistance were 87.9% and 35 £[/¡E with 4 periods ITO bilayers. Finally, the SCCO2 treatments with strong oxidizer H2O2 were proposed to modify surface property of ITO anode of a fluorescent OLED. The highest work function and surface energy of 5.5 eV and 74.8 mJ/m2 was achieved by the SCCO2/H2O2 treatment. For the OLED with 15 min SCCO2 treatment at 4000 psi, the turn-on voltage and maximum power efficiency of 6.5 V and 1.94 lm/W were obtained. The power efficiency was 19.3% and 33.8% higher than those of the OLEDs with oxygen plasma treated and as-cleaned ITO anodes.
132

Electrostatic layer-by-layer assembly of hybrid thin films using polyelectrolytes and inorganic nanoparticles

Peng, Chunqing 01 April 2011 (has links)
Polymer/inorganic nanoparticle hybrid thin films, primarily composed of functional inorganic nanoparticles, are of great interest to researchers because of their interesting electronic, photonic, and optical properties. In the past two decades, layer-by-layer (LbL) assembly has become one of the most powerful techniques to fabricate such hybrid thin films. This method offers an easy, inexpensive, versatile, and robust fabrication technique for multilayer formation, with precisely controllable nanostructure and tunable properties. In this thesis, various ways to control the structure of hybrid thin films, primarily composed of polyelectrolytes and indium tin oxide (ITO), are the main topics of study. ITO is one of the most widely used conductive transparent oxides (TCOs) for applications such as flat panel displays, photovoltaic cells, and functional windows. In this work, polyethyleneimine (PEI) was used to stabilize the ITO suspensions and improve the film buildup rate during the LbL assembly of poly(sodium 4-styrenesulfonate) (PSS) and ITO. The growth rate was doubled due to the stronger interaction forces between the PSS and PEI-modified ITO layer. The assembly of hybrid films was often initiated by a polyelectrolyte precursor layer, and the characteristics of the precursor layer were found to significantly affect the assembly of the hybrid thin films. The LbL assembly of ITO nanoparticles was realized on several substrates, including cellulose fibers, write-on transparencies, silicon wafers, quartz crystals, and glasses. By coating the cellulose fibers with ITO nanoparticles, a new type of conductive paper was manufactured. By LbL assembly of ITO on write-on transparencies, transparent conductive thin films with conductivity of 10⁻⁴ S/cm and transparency of over 80 % in the visible range were also prepared. As a result of this work on the mechanisms and applications of LbL grown films, the understanding of the LbL assembly of polyelectrolytes and inorganic nanoparticles was significantly extended. In addition to working with ITO nanoparticles, this thesis also demonstrated the ability to grow bicomponent [PEI/SiO₂]n thin films. It was further demonstrated that under the right pH conditions, these films can be grown exponentially (e-LbL), resulting in much thicker films, consisting of mostly the inorganic nanoparticles, in much fewer assembly steps than traditional linearly grown films (l-LbL). These results open the door to new research opportunities for achieving structured nanoparticle thin films, whose functionality depends primarily on the properties of the nanoparticles.
133

Microfluidic Devices for Manipulation and Detection of Beads and Biomolecules

Jönsson, Mats January 2006 (has links)
This thesis summarises work towards a Lab-on-Chip (LOC). The request for faster and more efficient chemical and biological analysis is the motivation behind the development of the LOC-concept. Microfluidic devices tend to become increasingly complex in order to include, e.g. sample delivery, manipulation, and detection, in one chip. The urge for smart and simple design of robust and low-cost microdevices is addressed and discussed. Design, fabrication and characterization of such microdevices have been demonstrated using low-cost polymer and glass microfabrication methods. The manufacturing is feasible, to a large extent, to perform outside the clean-room, and has subsequently been the chosen technique for most of the work. Issues of bonding reliability are solved by using polymer adhesive tapes. A planar electrocapture device with LOC-compatibility is demonstrated where beads are immobilised and released in a flowing stream. Retention of nanoparticles by means of electric field-flow fractionation using transparent indium tin oxide electrodes is presented. Moreover, a cast PDMS 4-way crossing is enabling a combination of liquid chromatography and capillary electrophoresis to enhance separation efficiency. Sample transport issues and a new flow-cell design in a quartz crystal microbalance bioanalyzer are also investigated. Fast bacteria counting by impedance measurements, much requested by the pharmaceutical industry for biomass monitoring, is carried out successfully. In conclusion, knowledge in micro system technology to build microdevices have been utilised to manipulate and characterise beads and cells, taking one step further towards viable Lab-on-Chip instruments.
134

Μελέτη της επιφάνειας ITO-PET και της διεπιφάνειας NiPc/ITO-PET με φασματοσκοπίες φωτοηλεκτρονίων

Τσικριτζής, Δημήτρης 20 April 2011 (has links)
Σκοπός της παρούσας εργασίας είναι αρχικά να μελετηθεί η επιφάνεια του οξειδίου ινδίου κασσιτέρου που έχει αποτεθεί σε υπόστρωμα ΡΕΤ και να γίνουν πάνω σε αυτήν χημικές επεξεργασίες αλλά και ιοντοβολή, ώστε να παρατηρηθούν τι επιδράσεις έχουν αυτές οι κατεργασίες στην επιφάνεια και ενδεχομένως στο έργο εξόδου. Οι κατεργασίες επιλέχθηκαν επειδή είναι γνωστή από την βιβλιογραφία η επίδρασής τους στο ΙΤΟ που όμως έχει αποτεθεί σε γυαλί, και η σύγκριση με τα δικά μας αποτελέσματα θα δώσει χρήσιμες πληροφορίες για τις διαφορές των δύο υλικών καθώς και αν οι κατεργασίες αυτές μπορούν να χρησιμοποιηθούν και αν είναι χρήσιμες για την αύξηση του έργου εξόδου του ΙΤΟ-ΡΕΤ. Επίσης, στη συνέχεια έγιναν αποθέσεις οργανικού ημιαγώγιμου υλικού (NiPc) πάνω στο υπόστρωμα ΙΤΟ-ΡΕΤ το οποίο είχε επεξεργαστεί χημικά, με σκοπό να προσδιοριστεί η ηλεκτρονική δομή της διεπιφάνειας του οργανικού και του υποστρώματος, ώστε να μελετηθεί η επίδραση του ΙΤΟ-ΡΕΤ στην συμπεριφορά της διεπιφάνειας και να διαπιστωθεί η πιθανή εφαρμογή τους σε ηλεκτρονικές διατάξεις. / The purpose of this thesis is to study the surface of indium tin oxide deposited on PET substrate after some chemical treatments and Argon Sputtering, in to order to investigate what effects these treatments have on the surface and possibly in the work function. The treatments were chosen because it is known from the literature the influence they have on the ITO, but which it has been deposited on glass, and a comparison of our results will provide useful information about differences between the two materials, and whether these treatments can be useful for increasing the work function of ITO-PET. Also, it was deposited organic semiconductor material (NiPc) onto the ITO-PET substrate that was chemically processed in order to determine the electronic structure at the interface of organic substrate and to study the effect of ITO-PET in the behavior of interface and to determine its possible application in electronic devices.
135

Přirozené monopoly v elektroenergetice a plynárenství (právní aspekty) / Natural monopolies in Electricity and Gas Sectors (the legal aspects)

Kadlecová, Eliška January 2017 (has links)
The purpose of this diploma thesis is to use relevant economic knowledge for the analysis of the key legal aspects of the natural monopoly, particularly the main theoretical aspects thereto. The interpretation is not limited to principle features, however, it covers also the related issues. The text is focused mainly on electricity and gas industries. Apart from applicable law and legal books, the relevant case law of the Constitutional Court and Supreme Administrative Court of Czech Republic has been also a significant source of knowledge hereto. The European Union legal regulations and expert opinions of the European Commission have been taken into account as well. The diploma thesis is divided into five chapters. The first chapter is focused on economic aspects of the applicable law. It provides thorough overview concerning the model and its introduction into reviewed fields. The principal information, historical background and view of the critics are introduced. This chapter also labels the entities under the Czech law that are considered to be the natural monopolies. Furthermore, three basic fields of legal institutes that are subject to subsequent review are outlined. The second chapter defines elementary terms relevant for further research. Specifically, it covers the distribution,...
136

Charakterizace elektronických vlastností nanodrátů pro elektrochemii / Characterization of electronic properties of nanowires for electrochemistry

Kovařík, Martin January 2019 (has links)
Elektrochemické metody nacházejí využití v mnoha aplikacích (např. senzorice, skladování el. energie nebo katalýze). Jejich nespornou výhodou je nízká finanční náročnost na přístrojové vybavení. Abychom lépe porozuměli procesům probíhajícím na elektrodách, je dobré znát elektronickou pásovou strukturu materiálu elektrody. Úkolem této práce je vyhodnotit výstupní práci a pozici hrany valenčního pásu nových materiálů pro elektrody, konkrétně cínem dopovaného oxidu india pokrytého nanotrubicemi sulfidu wolframičitého. Ultrafialová fotoelektronová spektroskopie a Kelvinova silová mikroskopie jsou metody použité pro tuto analýzu. Zvláštní důraz je kladen na přípravu vzorků elektrod pro měření, aby nedošlo k nesprávné interpretaci výsledků vlivem vnějších efektů jako je např. kontaminace nebo modifikace povrchu.
137

Optimalizace tenkých oxidových vrstev kovových materiálů / Optimization of thin films of metal oxide materials

Vítek, Jiří January 2014 (has links)
This thesis is focused on the description of the method of reactive sputtering of thin films. Currently, there are many ways how to create thin films and there are many applications of thin films in various industrial sectors. In this paper at the first are listed the issue of thin films, followed by an overview of the deposition techniques and of the chemical analysis of deposited thin films. It also describes the four-point measurement method of sheet resistance, mechanical test of adhesion and optical properties. At the end of the theoretical part are described the material composition of the deposited films. The goal of the practical part is to optimize the deposition process of the mixed layer of indium tin oxide (In2O3: SnO2) and contribute to the overall understanding of the influence of annealing on the layer. There were created six series of samples with that applied layers. First, the work focused on examining of the influence of annealing on the throughput in the whole measuring range, and then comparing the series due to the transmittance in the visible light spectrum. Furthermore were compared the value of sheet resistance of unannealed and subsequently annealed samples.
138

Itô’s Lemma

Grunert, Sandro 10 June 2009 (has links)
Itô’s Lemma Ausarbeitung im Rahmen des Seminars "Finanzmathematik", SS 2009 Die Arbeiten des japanischen Mathematikers Kiyosi Itô aus den 1940er Jahren bilden heute die Grundlage der Theorie stochastischer Integration und stochastischer Differentialgleichungen. Die Ausarbeitung beschäftigt sich mit Itô's Kalkül, in dem zunächst das Itô-Integral bezüglich diverser Integratoren bereitgestellt wird, um sich anschließend mit Itô's Lemma bzw. der Itô-Formel als grundlegendes Hilfsmittel stochastischer Integration zu widmen. Am Ende wird ein kurzer Ausblick auf das Black-Scholes-Modell für zeitstetige Finanzmärkte vollzogen. Grundlage für die Ausarbeitung ist das Buch "Risk-Neutral Valuation" von Nicholas H. Bingham und Rüdiger Kiesel.
139

RF überlagertes DC-Sputtern von transparenten leitfähigen Oxiden

Heimke, Bruno 19 March 2013 (has links)
Die vorliegende Dissertation befasst sich mit dem RF- überlagerten DC-Sputtern von Indiumzinnoxid und aluminiumdotierten Zinkoxid. Bei dem dafür entwickelten synchron gepulsten RF/DC-Verfahren werden die zu untersuchenden Materialien gleichzeitig mit Hilfe eines RF- und eines PulsDC-Generators gesputtert. Ein wesentliches Resultat der Untersuchungen ist, dass durch RF- überlagertes DCSputtern Schichten abgeschieden werden können, die im Vergleich zum DC- bzw. PulsDC-Sputtern geringere spezifische Widerstände aufweisen. Dies ist auf eine Verringerung von Defekten in den abgeschiedenen Schichten zurückzuführen. Es konnte anhand der Untersuchungen gezeigt werden, dass fur die Abscheidung von Indiumzinnoxid und aluminiumdotiertem Zinkoxid die Substrattemperatur beim RF überlagerten DC-Sputtern gegenüber dem DC-Sputtern um bis zu 100°C verringert werden kann.
140

Fabrication of Inorganic Oxide Nanofibers Using Gas Jet Fiber Spinning Process and Their Applications in Photocatalytic Oxidation

GHOSH, MONOJ 16 October 2017 (has links)
No description available.

Page generated in 0.1143 seconds