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Selective growth of GaN on SiN
Hulva, Jan ; Kolíbal, Miroslav (referee) ; Mach, Jindřich (advisor)
This bachelor's thesis deals with the selective growth of gallium and gallium nitride on silicon nitride (SiN) substrates. Thin silicon nitride layers are deposited on silicon substrates. Oxide structures are prepared by the local anodic oxidation method (LAO) on SiN substrates. These surfaces can be editionally modified by etching in hydrofluoric acid. Modified substrates are used for the deposition of gallium or gallium nitride under ultra-high vacuum conditions. Consequently, ordering of deposited material was studied in areas modified by LAO. Chemical state of layers is studied by X-ray photoelectron spectroscopy. Morphology of surfaces is measured by the atomic force microscope (AFM).
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Functionalized nanostructures
Váňa, Rostislav ; Kvapil, Michal (referee) ; Kolíbal, Miroslav (advisor)
This thesis deals with functionalized nanoparticles. In the first part there are mentioned materials suitable for a functionalization, the usage of functionalized nanoparticles in medicine and biochemistry and detection methods of changes of optical properties. In the second part changes of optical properties after functionalization are investigated by spectroscopic ellipsometry and FTIR spectroscopy.
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Design of an ion source for sputtering
Glajc, Petr ; Voborný, Stanislav (referee) ; Kolíbal, Miroslav (advisor)
This bachelor's thesis deals with the development of a new type of an ion source. The aim is to design a saddle-field ion source for sputtering. The unique property of the design is that it combines classical cylindrical-symmetry saddle-field ion source with a hot cathode made of tungsten. In the first part of the thesis an overview of the published research in the field of ion sources is presented. The second part deals with an electrostatic-optical design of the source and with simulations of the electrostatic field including trajectories of electrons and ions. Also a crude estimation of the source parameters is made. In the third part the construction design based on previous simulations is described.
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Germanium island morphology in the presence of Gallium and Gold
Pejchal, Tomáš ; Čechal, Jan (referee) ; Kolíbal, Miroslav (advisor)
This bachelor's thesis deals with germanium island morphology in the presence of gold, silver and gallium. The islands were grown on Ge(111) surface by means of evaporation under the UHV conditions. In the paper a background research on the surface reconstructions of the metals on Ge(111) is presented. It is demonstrated that the island concentration, size and shape are affected by the presence of metals and the deposition temperature. The surface structure and the morphology of the samples were investigated by RHEED and SEM.
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Semiconductor nanowire growth modelling
Kovács, Roland ; Bartošík, Miroslav (referee) ; Kolíbal, Miroslav (advisor)
This bachelor’s thesis deals with modelling of semiconductor nanowires growth. The work describes the mechanism of growth using the VLS method. The main objective is to simulate the distribution of eutectic material in a droplet in the initial stage of growth. Mathematical models describing different situations of material diffusion in the droplet were depeloped. The simulation model is programmed in MATLAB.
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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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Fabrication of Nanostructures Using Focused Ion Beam
Bartoš, Radko ; Tomanec, Ondřej (referee) ; Kolíbal, Miroslav (advisor)
This bachelor´s thesis deals with the ion-beam milling. Focused ion beam instrument is presented, as well as possibilities of initial setup conditions, which finally result in different nanostuctures´ shapes. In the thesis the methodology of fabrication and analysis of the nanostructures is described. Ideal ion beam setup conditions were deduced so that the nanostructures are of requested shape.
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Fabrication of SiO2 by anisotropic etching of silicon
Balajka, Jan ; Kolíbal, Miroslav (referee) ; Urbánek, Michal (advisor)
The aim of the bachelor's thesis is the fabrication of silicon dioxide (SiO2) membranes on silicon (Si) substrate by anisotropic etching of silicon. Masks for anisotropic silicon etching were prepared by electron beam litography and SiO2 wet etching. Individual steps of membrane fabrication are described, including used experimental conditions. In order to optimize the fabrication process, etch rates of Si/SiO2 in several solutions were measured. Results of the measurements are included in the thesis. Fabricated membranes were characterised by optical microscopy, scanning electron microscopy and spectroscopic reflectometry. Methods used for fabrication and analysis of defined structures created by anisotropic silicon etching are briefly summarized.
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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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