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SELECTIVE EMITOR FOR THERMOPHOTOVOLTAIC SYSTEMS
Šimonová, Lucie ; Hrzina,, Pavel (referee) ; Šály,, Vladimír (referee) ; Vaněk, Jiří (advisor)
The work is focused on research and development of a suitable method for creating a selective emitter for the visible and near infrared region so that they are able to work optimally together with silicon photovoltaic cells in a thermophotovoltaic system. The aim of the work was to develop a new method of creating very fine structures outside the current standard, which will increase the emissivity of the base material to meet the needs of a selective emitter for the VID and NIR region. The methods available to us for the creation of structures were chosen, from which we eliminated all unsuitable ones and we introduced the optimal procedure and parameters for their creation for the selected method. In this work, we focused on both ceramic and metallic materials, whose heat resistance and selective properties are key to this work. Part of the development of the emitter structures was also the need for pretreatment of the substrate itself, where great emphasis was placed on the purity of materials and surface roughness. Since ceramic materials cannot achieve a surface roughness so low that the desired structures can be formed, these materials have been purposefully used primarily for the purpose of combining the base material with thin layers of other high temperature material. Their compatibility and suitability were verified in terms of adhesion and subsequent heat resistance. The main material for the formation of fine structures was purposefully chosen tungsten, for which we verified the influence of the formed structure on the emissivity as well as the thermal stability during long-term exposure to high temperatures. The work thus represents not only a new method of creating very fine structures, which are not normally formed in such subtlety, but also opens the way to new possibilities of combining more materials to achieve the required selectivity of the thermophotovoltaic emitter.
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SMV-2019-05: Phase grids
Krátký, Stanislav ; Matějka, Milan ; Chlumská, Jana ; Horáček, Miroslav ; Kolařík, Vladimír ; Meluzín, Petr ; Král, Stanislav
Development of phased gratings manufacturing for use in transient grating spectroscopy. Possible approaches for phased gratings design were studied during the development to achieve the maximum efficiency for two different wavelengths. Theoretic simulations showed that the grating has to be adjusted for the value of wavelength (the depth of the grating) between two desired values of wavelength to achieve the maximum efficiency in first diffractive orders. The samples were manufactured with use of e-beam lithography and reactive ion etching.
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SMV-2019-04: Large-area nanostructures preparing
Horáček, Miroslav ; Kolařík, Vladimír ; Matějka, Milan ; Krátký, Stanislav ; Chlumská, Jana ; Meluzín, Petr ; Král, Stanislav
The development of sandwich nanostructures on doped silicon substrate. The dimension of nanostructures and their pitch is very close to the capability of used e-beam system Raith EBPG5000+. Thin silicon nitride layer was prepared on doped silicon substrate. This layer is needed for wet etching of silicon. The golden markers needed for direct writing of multiple patterns were prepared by the way of e-beam lithography and vacuum evaporation. Mask in the resist layer was exposed for etching of the silicon nitride mask by reactive ion etching in the next step. Wet etching of silicon was carried out after the mask was prepared. Small pyramids were created by the etching process. The last lithography step was preparation of the mask over the pyramids. Thin aluminum layer in the areas where the pyramids are presented was prepared by the way of vacuum evaporation and lift-off technique.
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SMV-2019-03: Thin membranes
Krátký, Stanislav ; Matějka, Milan ; Chlumská, Jana ; Horáček, Miroslav ; Kolařík, Vladimír ; Meluzín, Petr ; Král, Stanislav
The development of technology for preparation of very thin silicon nitride membrane for use in low energy electron spectroscopy. Several techniques for preparation of thin membranes were tested during the development – wet etching, reactive ion etching, plasma etching, low-frequency plasma etching. Comparative method for the measurement of such thin membranes was developer also.
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Gecko mimicking surfaces
Fecko, Peter ; Boušek, Jaroslav (referee) ; Pekárek, Jan (advisor)
Adhezní schopnosti gekona byly předmětem mnoha studií a inspirací pro vytvoření mnoha napodobenin. Tato práce navrhuje vlastní verzi umělých gekoních struktur ve tvaru mikroskopických pilířů, které by vykazovaly adhezní vlastnosti srovnatelné s tlapkou gekona. Vyrobeny byli struktury z polymeru Parylen C pomocí fotolitografie a technik na leptání křemíku. Dalším cílem bylo různými metodami pro modifikaci povrchu a charakterizaci vytvořených struktur, které určí adhezní síly těchto povrchů, před a po modifikacích.
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SMV-2018-04: Planar microstructures for optical applications
Horáček, Miroslav ; Kolařík, Vladimír ; Matějka, Milan ; Krátký, Stanislav ; Chlumská, Jana ; Meluzín, Petr ; Král, Stanislav ; Fořt, Tomáš ; Oulehla, Jindřich ; Pokorný, Pavel
The development of planar microstructures for optical applications, and subsequent realization of samples by the way of e-beam lithography and other techniques. Project deals with material study suited for the fabrication of planar microstructures in thin metallic layer with respect to achievable resolution and fulfilling the absorbance parameters for particular application. E-beam lithography is used for preparation the motif in resist layer, which is masking layer for the etching of metallic layer by various techniques (wet etching, reactive ion etching). Technical documentation of developed processes and prepared samples are also the part of the project.
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Controlled structuring of self-assembled polystyrene microsphere arrays by two different plasma systems
Domonkos, Mária ; Ižák, Tibor ; Stolcova, L. ; Proška, J. ; Kromka, Alexander
In this study we present a successful manipulation of microspheres by reactive ion etching (RIE). A self-assembled monolayer close-packed array of monodisperse polystyrene microspheres (PM) with diameter of 471 nm was used as the primary template. The PM templates were processed in two different RIE systems: (i) capacitively coupled radiofrequency plasma (CCP) and (ii) dual plasma system which combines CCP and pulsed linear-antenna microwave plasma (PLAMWP). The influence of process conditions on the PM geometry was systematically studied by scanning electron microscopy (SEM). It was found out that choosing optimal parameters results in a tunable diameter of PM with various shapes (from spheres to pyramid-like structures) while keeping their periodic hexagonal ordering.
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