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The oxygen modification of the graphene structures for biosensors
Mikerásek, Vojtěch ; Bartošík, Miroslav (referee) ; Mach, Jindřich (advisor)
The bachelor thesis deals with the modification of CVD graphene by oxygen atoms. The theoretical part describe the structure of graphene oxide and its physical properties. Methods of production of this material and its use in biosensors are also described. The practical part describes the preparation of monolayer graphene on a silicon wafer. The main attention was paid to the oxidation of graphene by atomic oxygen and its modification in oxygen plasma. The samples were measured during process of oxidation at individual time intervals using XPS.
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Design of an effusion cell for the deposition of Sn and Zn ultrathin layers
Horák, Stanislav ; Kolíbal, Miroslav (referee) ; Mach, Jindřich (advisor)
This bachelor thesis deals with the design and the construction of effusion cells for the deposition of zinc and tin ultrathin layers. In the introductory part there is an explanation of principles of eusion cells' functions, like a molecular beam epitaxy (MBE) or a construction of the efussion ow. Furthermore, the work describes a general principles of a ccreation of the atom sources. Theoretical part ends with review about the growth of ultrathin layers and nanostructures of zinc, tin and their compounds. Experimental part provides a design of the effusion cells with radiation heating from silicon carbide and heating by electrons impact. The complete drawing documentation of the designed effusion cells is included in the attachment.
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The photoluminescence properties measurement of ultrathin films
Metelka, Ondřej ; Mach, Jindřich (referee) ; Šamořil, Tomáš (advisor)
The thesis briefly describes the principles and types of luminescence. In the first following research of study is also discussed the equipment which is applicable to photoluminescence experiments, including the arrangement. The second research focuses on the influence of the properties of gallium nitride (GaN) (ultra) thin films and other structures prepared by various ways on shape of photoluminescence spectra. The paperwork also describes the further optimization of photoluminescent apparatus used for the measurement of photoluminescence spectrum in the UV light radiation which is located at the Institute of Physical Engineering at the Technical University. The extension of measurements at low temperatures (design and construction of its own cryostat) is added. The conclusion concernes the test measurements to determine the effect of various settings of the apparatus on the resulting measured photoluminescence spectrum.
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Design of the atomic source producing carbon beams for deposition of graphene in UHV conditions
Horáček, Matěj ; Kolíbal, Miroslav (referee) ; Mach, Jindřich (advisor)
This bachelor's thesis deals with the design of the atomic source of carbon beams for deposition of graphene in UHV conditions. In the first part, problems on the growth of ultrathin layers, the theory of atomic beams and molecular beam epitaxy are described. The second part is aimed to graphene layers - especially the growth of graphene using molecular beam epitaxy. In the third part, the detection of carbon atomic beams is discussed. The practical part of this bachelor's thesis deals with the design and the construction of high-temperature atomic source of carbon. In the conclusion the obtained results are discussed.
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Development and Application of an UHV Equipment for Deposition of Thin Films (Atomic and Ion Systems)
Mach, Jindřich ; Čech, Vladimír (referee) ; Lencová, Bohumila (referee) ; Šikola, Tomáš (advisor)
In the thesis the development of two equipment for preparation of ultrathin films under ultrahign vacuum conditions (UHV) is discussed. Here, additionally to a brief description of theoretical principles, more details on the design of these units are given. In the first part the design of a thermal source of oxygen or hydrogen atomic beams is discussed. Further, a design and construction of an ion–atomic beam source for ion-beam assisted deposition of thin films is detailed. The source combines the principles of an efusion cell and electron-impact ion beam source generating ions of (30 – 100) eV energy. The source has been successfully applied for the growth of GaN on the Si(111) 7x7 substrate under room temperature.
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Deposition of Ga nanostructures on graphene membranes
Severa, Jiří ; Mikulík, Petr (referee) ; Mach, Jindřich (advisor)
This diploma thesis deals with the preparation of the graphene membranes for depo-sition of gallium atoms by the molecular beam epitaxy. In the first part properties ofgraphene and methods of its production are described. Second part focuses on the gra-phene membranes, their specific properties, applications and methods of production. Thirdpart describes growth theory of the thin films. Practical part is focused on preparationof graphene membranes, which consists of covering the holes in the silicon substrate bygraphene layer. For that mechanical exfoliated and chemical vapor deposited graphenewere used. Subsequently, gallium atoms were deposited on these membranes by molecularbeam epitaxy and in situ observed by scanning electron microscopy.
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The deposition of CaF2 ultrathin layers on graphene substrate
Caesar, Radek ; Nebojsa, Alois (referee) ; Mach, Jindřich (advisor)
This master’s thesis is focused on preparation and analysis of ultrathin CaF2 (calcium fluoride) films on a graphene substrate. CaF2 was deposited in UHV conditions at substrate temperatures in the range from 20 °C to 400 °C. The material was deposited on Si(111) with a native SiO2 layer and on a substrate with a CVD graphene layer. The deposited films were analyzed by XPS, AFM and SEM. Moreover four different sample holders for deposition purposes were designed in this work.
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Epitaxial growth of cobalt islands via oxide mediated epitaxy
Stará, Veronika ; Kolíbal, Miroslav (referee) ; Čechal, Jan (advisor)
This bachelor thesis deals with preparation, growth and analysis of cobalt thin films. The films are formed on silicon (111) samples covered with a thin layer of native oxide SiO2. Cobalt thin films were prepared using oxide mediated epitaxy method with the effusion cell as a source of cobalt atoms. Composition and morphology of the resulting Co system was studied as a function of the annealing temperature. Another goal of this research was to determine the dependence of the final island shape on the amount of deposited material and substrate orientation. The prepared structures were analyzed using X-ray photoelectron spectroscopy, atomic force microscopy and scanning electron microscopy. To determine the thickness of subsurface islands the samples were etched in buffered hydrofluoric acid and analyzed using above mentioned methods.
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GaN deposition on a tungsten substrate
Pikna, Štěpán ; Piastek, Jakub (referee) ; Čalkovský, Vojtěch (advisor)
This bachelor thesis is focused on deposition of GaN nanocrystals on the etched tungsten tips. Motivation was to prepare these GaN structures on the Schottky cathode made by company ThermoFisher Scientific and measure its field emission. In the theoretical part of the thesis GaN and tungsten field emission properties are introduced. The experimental part begins with tungsten tip etching optimalization, where the right values for best tips are temperature 20 °C, depth of the tip 2,5 mm and solution NaOH used. Further the gallium structures were prepared on these tips using molecular beam epitaxy (MBE). The right temperature to prepare GaN nanocrystals was determined as 200 °C. The deposition of gallium was set to 2 hours and following nitridation was 3 hours. Finally, the field emission from GaN prepared on copper foil with graphene was measured and compared with other experiments.
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