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Optimization of UHV SEM for nanostructure study in wide temperature range
Axman, Tomáš ; Zigo,, Juraj (referee) ; Bábor, Petr (advisor)
This diploma thesis deals with the optimization of ultra-high vacuum scanning electron microscope - UHV SEM, which is developed within the Amispec project in cooperation with BUT, Institute of Scientific Instruments of the Czech Academy of Science and Tescan Brno, s.r.o. The theoretical part deals with the description of the actual state of the developed equipment and the research of competing systems. The next part describes the optimization of the sample holder and the pallet receptor for studying nanostructures over a wide range of temperatures. Part of the optimization is the sapphire thermal diode development and experimental verification of the functionality of the designed components. This is followed by the verification of the functionality of the whole system for the transport of samples to the UHV area, deposition with effusion cell and in-situ observations.
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Preparation and characterization of nanostructured III-V semiconductor materials
Maniš, Jaroslav ; Kostelník,, Petr (referee) ; Hospodková,, Alice (referee) ; Šikola, Tomáš (advisor)
Předkládaná dizertační práce se zabývá výrobou a analýzou gallium nitridových (GaN) nanostruktur ve třech odlišných formách. V prvním případě byl zkoumám trojdimenzionální GaN ve formě nanokrystalů rostených na grafenu. Nanokrystaly byly připraveny s využitím techniky droplet epitaxy, která mimo jiné umožňuje růst nanostruktur za nízké teploty substrátu (T = 200°C). Studium se zaměřovalo jak na charakterizaci kvality připravených nanokrystalů, tak na statistický popis růstu. V dalším kroku byly připravené struktury využity pro výrobu fotodektoru citlivého na ultrafialové světlo. Výroba fotodektoru a jeho úspěšné použití slouží jako základ pro navazující výzkum. Ve druhém případě byly studovány dvoudimenzionální GaN nanostruktury, které byly rovněž připraveny za nízké teploty křemíkového substrátu. Následná analýza se soustředila na popis krystalové struktury a prvkovou analýzu, neboť byly takovéto struktury pozorovány vůbec poprvé. Další rozvoj možností přípravy těchto nanostruktur je předmětem navazujícího výzkumu. Ve třetím případě byly zkoumány jednodimenzionální GaN nanodráty připravené na safírovém substrátu. Účelem tohoto projektu bylo získání datasetu pro ověření teoretického modelu, který popisuje růst horizontálních nanodrátů. Na základě sběru a analýzy dat se podařilo modelovat růstovou dynamiku GaN nanodrátů, která byly v souladu s teoretickým modelem.
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Modular design for in-atomizer preconcentration of hydride forming elements with AAS detection
Novák, Petr ; Kratzer, Jan (advisor) ; Korunová, Vlasta (referee)
Modular design of hydride trap-and-atomizer device for AAS is constructed and tested. Modular design enables to test different preconcentration surfaces easily. Efficient in- atomizer preconcentration allows to reach detection limits of hydride forming elements at ultratrace levels. Bismuth and arsenic were chosen as model analytes and their preconcentration efficiencies were quantified employing quartz and sapphire as preconcentration surfaces. The results reached in the modular design were compared to those found previously in the compact quartz trap-and-atomizer device. The performance of the modular design is fully comparable with that of compact trap-and-atomizer design. Modular design can thus be employed for testing of novel preconcentration surfaces.
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Design of manufacturing simulations of a flatplate pulsating heat pipe
Pontecorvo, Matteo
Currently, a research team in the University of Brighton, in collaboration with the European Space Agency (ESA), is developing a pulsating heat pipe that will eventually be launched and tested in space, with the International Space Station (ISS) as destination, for research into passive thermal devices and their behaviour in a vacuum. The approved pulsating heat pipe design incorporates one titanium plate, which is classified as a metal, and one aluminum-oxide sapphire plate that is classified as a ceramic. At the moment, the team is faced with the challenge of bonding the two plates together since, using convectional manufacturing methods, the parts fail due to the high level of induced stress. A research into manufacturing processes to bond together titanium and sapphire is essential to ensure that the final device will operate for several weeks (maybe even months) without leaking and the need for maintenance. The project explores potential manufacturing processes aimed to bond together these materials and subsequently propose a solution. Furthermore, static and thermal analyses are carried out with the aid of SolidWorks to exploit potential points of failure due to stress concentrations induced by cooling after bonding. The results indicate that both titanium and sapphire are capable of sustaining the induced stresses but, due to the complex geometry of the pulsating heat pipe at the contact surface, the bonding agent is likely to fail due to the induced stresses.
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Optimization of UHV SEM for nanostructure study in wide temperature range
Axman, Tomáš ; Zigo,, Juraj (referee) ; Bábor, Petr (advisor)
This diploma thesis deals with the optimization of ultra-high vacuum scanning electron microscope - UHV SEM, which is developed within the Amispec project in cooperation with BUT, Institute of Scientific Instruments of the Czech Academy of Science and Tescan Brno, s.r.o. The theoretical part deals with the description of the actual state of the developed equipment and the research of competing systems. The next part describes the optimization of the sample holder and the pallet receptor for studying nanostructures over a wide range of temperatures. Part of the optimization is the sapphire thermal diode development and experimental verification of the functionality of the designed components. This is followed by the verification of the functionality of the whole system for the transport of samples to the UHV area, deposition with effusion cell and in-situ observations.
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Modular design for in-atomizer preconcentration of hydride forming elements with AAS detection
Novák, Petr ; Kratzer, Jan (advisor) ; Korunová, Vlasta (referee)
Modular design of hydride trap-and-atomizer device for AAS is constructed and tested. Modular design enables to test different preconcentration surfaces easily. Efficient in- atomizer preconcentration allows to reach detection limits of hydride forming elements at ultratrace levels. Bismuth and arsenic were chosen as model analytes and their preconcentration efficiencies were quantified employing quartz and sapphire as preconcentration surfaces. The results reached in the modular design were compared to those found previously in the compact quartz trap-and-atomizer device. The performance of the modular design is fully comparable with that of compact trap-and-atomizer design. Modular design can thus be employed for testing of novel preconcentration surfaces.
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