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Reliability of WBG Transistors
Horký, Jan
Silicon Carbide (SiC) and Gallium Nitride (GaN) transistors have the potential to revolutionize power electronics industry. They have better resistance, size, and efficiency than current Silicon (Si) transistors. On the other hand, as Silicon FET has been used for several decades, its reliability and robustness has been well known and documented. The aim of this paper is to present a review of reliability and radiation issues of GaN and SiC transistors in order to mitigate potential issues in future designs.
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Morphology study of ultra thin layers by XPS analysis of multiple peaks of a single element
Pokorný, David ; Šik, Ondřej (referee) ; Polčák, Josef (advisor)
This diploma thesis deals with methodology of thin film thickness determination using X-ray radiation of silver anode which provides radiation with energy of 2984,3 eV. This energy is twice as high as the standard aluminium radiation which allows a measurement of new photoelectron lines with higher bonding energy and it also provides thanks to the higher photoelectron energy greater information depth. In order to get the right results it was necessary to calibrate the spectrometer Kratos Axis Supra in the silver anode mode first and found out the form of the transmission function. The determination of the thickness of the thin layer was demonstrated by the comparation of the ratio of different photoelectron lines intensities with the theoretical model. For that purpose was specifically used the Si 1s and Si 2p peak bound in the substrate in the Si-Si bonding or in the thin oxid layer in the Si-O bonding. The results show that for thin SiO2/Si film thickness determination is the best to use the intensity ratio of only one photoelectron line. A silver anode however provides greater information depth.
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Kibble balance
Tomanec, Jakub ; Kunz, Jan (referee) ; Beneš, Petr (advisor)
The bachelor thesis consists of three sections. The first section explains the revision of the international system of units (SI), which took place in 2018 at the 26th General Conference on Weights and Measures (CGPM). The second section explains the concept of Kibble balance and introduces some of the created projects. The third section of the work was the creation of a prototype Kibble balance, evaluation of measured data and design of future modifications of the prototype.
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Preparation of graphene layers by various methods and characterization of their properties
Zahradníček, Radim ; Bartošík, Miroslav (referee) ; Lišková, Zuzana (advisor)
This bachelor's thesis deals with the production of graphene by different methods. Graphene was prepared by mechanical exfoliation and chemical methods. Graphene oxide (GO) was first prepared by modified Hummers method and disolved the solution in isopropyl alcohol. It was subsequently reduced by photoreduction, UV radiation and thermal reduction. Produced graphene samples were characterized using optical microscopy, electron microscopy, atomic force microscopy, Raman spectroscopy and X$-$ray photoelectron spectroscopy. Measurement results and evaluation of production quality of graphene are shown in this work.
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COMMUNITY OF EVERYDAY
Mikušková, Nina ; McKee,, Francis (referee) ; Klodová, Lenka (advisor)
Been There Together is a single player game in an online and offline form of cards inspired by event scores. The game is designed to be played by individuals in public spaces, while they are surrounded by strangers. It serves as a pretext for social inclusion. The game can be played online, as a mobile phone application and as a DIY card game for download. The game was designed as an alternative to mobile games, and instead of pulling the player into a virtual reality, it encourages their perception of society and the surroundings. By providing challenges, context and aesthetic pleasure, it creates an exciting experience that contrasts with ordinary daily activities. Its purpose is to overcome the individual's alienation in society. By simple questions and tasks, the player is drawn into a magic circle of play in reality, in areas that are not normally intended for play. It creates a temporary world in the midst of an ordinary world, transforming everyday experience and the individual's perception of public spaces. The game is inspired by Fluxus group's "event scores" as well as by the Situationist International's concept of "dérive", a method of unplanned journeying through urban landscapes. The player can choose between 4 difficulty levels and decide which intensity of play they prefer. Its unobtrusive design allows the player to play the game without noticeably changing their behaviour in public, and it is entirely their decision if they want to admit that they are playing the game to bystanders. Thanks to the guise of a game, the player feels safe to interact with a stranger, to ask for help or to ask questions of people whom they are encountering for the first time. The game creates real social interaction, with legal and economic consequences that reach beyond the magic circle.
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Preparation of Ag/Co/Ag Trilayers
Burda, Pavel ; Kolíbal, Miroslav (referee) ; Čechal, Jan (advisor)
The Bachelor's thesis is aimed to the preparation of silver and cobalt ultrathin films. The films are formed on modified surfaces of crystalline silicon substrates (SiO2/Si(111), Si(111) ?H, Si(111) 7×7) and amorphous SiO2 in a form of a quartz glass. Thin films are grown using an effusion cell for Molecular Beam Epitaxy (MBE). Surface modified surfaces are covered subsequently by a silver, cobalt and silver thin layer. The individual film thickness is 6 nm. Consequently the samples are studied by the X-ray Photoelectron Spectroscopy (XPS) and the Atomic Force Microscopy (AFM). The morphology of thin films and growth modes are compared among the substrates. Growth modes change with the surface modification type. Complete trilayer system Ag/Co/Ag was prepared on SiO2/Si(111) and Si(111) 7×7. Such system can be employed in plasmonics in order to allow the control of surface plasmon polariton properties by an external magnetic field.
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Growth ultrathin of layers Au
Beránek, Jiří ; Kolíbal, Miroslav (referee) ; Mach, Jindřich (advisor)
The aim of this thesis is to study growth of ultrathin gold layers prepared by MBE (Molecular beam epitaxy) in UHV conditions. Differently modified sillicon served as a substrate and depositions were done at different temperatures of a substrate. Samples were analyzed by ToF LEIS for thickness, morfology was examined by SEM and AFM. X-ray photoelectron spectra were taken for chemical analysis. Gathered data together with their evaluation contribute to description and understanding of some processes during deposition and subsequent exposure of the sample to high temperatures. Experimental data and conslusions also prowide basis for further experiments and development of potential applications.
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Kibble balance
Tomanec, Jakub ; Kunz, Jan (referee) ; Beneš, Petr (advisor)
The bachelor thesis consists of three sections. The first section explains the revision of the international system of units (SI), which took place in 2018 at the 26th General Conference on Weights and Measures (CGPM). The second section explains the concept of Kibble balance and introduces some of the created projects. In the third section of the work, the prototype of Kibble balance was realized. The fourth section contains the measurements of the prototype’s properties of the and the evaluation of the measured data. In the last section, possible sources of uncertainty and their possible solutions were evaluated.
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Kibble balance
Tomanec, Jakub ; Kunz, Jan (referee) ; Beneš, Petr (advisor)
The bachelor thesis consists of three sections. The first section explains the revision of the international system of units (SI), which took place in 2018 at the 26th General Conference on Weights and Measures (CGPM). The second section explains the concept of Kibble balance and introduces some of the created projects. The third section of the work was the creation of a prototype Kibble balance, evaluation of measured data and design of future modifications of the prototype.
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