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The preparation and characterisation of electrical properties of graphene CVD monocrystals
Hulva, Jan ; Rezek, Bohuslav (referee) ; Mach, Jindřich (advisor)
Chemická depozice grafenu z plynné fáze (CVD) je metoda schopná produkovat grafenové monovrstvy velkých velkých rozměrů. Část experimentální práce v rámci této diplomové práce je zaměřena na depozici a analýzu grafenových monokrys- talů připravených metodou CVD na měděném substrátu. Pro analýu grafénových domén je použito technik optické mikroskopie, elektronové mikroskopie, mikroskopie atomárních sil a Ramanovy spektroskopie. Úkolem další části je studium defektů po- zorovaných na mědi po depozici grafenu pomocí energiově disperzní rentgenové spek- troskopie. Množství těchto defektů bylo odstraněno úpravou depozičního systému ačkoliv takto nebylo dosaženo eliminování všech typů defektů. Poslední část této práce se zabývá měření elektro-transportních vlastností grafenu. Výsledky této části zahrnují měření ve vakuu se zapojeným hradlovým napětím a měření při nízkých teplotách v magnetickém poli.
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Preparation of 2D materials in an ultrahigh vacuum electron microscope
Dymáček, Michal ; Bartošík, Miroslav (referee) ; Kolíbal, Miroslav (advisor)
This thesis is devoted to preparation of multilayer graphene and h-BN by CVD method. In the theoretical part of this thesis, both materials are introduced, as well as the CVD method and SEM. In the experimental part, the equipment and samples are described, as well as the computer codes, that were made within this work and used for analysis of taken images, and experiments, that were carried out. Utilizing in-situ analysis in ultra-high vacuum scanning electron microscope, the goal was to answer a question how is the multilayer graphene formed on the surface. Also, the first experiments of preparation of h-BN in this aparature were carried out.
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Synthesis of low-crosslinked polymers by plasma polymerization
Kuchtová, Štěpánka ; Bránecký, Martin (referee) ; Čech, Vladimír (advisor)
This bachelor thesis deals with plasma enhanced chemical vapour deposition (PECVD), specifically plasma polymerisation, which has been used for the synthesis of low density crosslinked polymer thin films. Organosilicon thin films were deposited on a silicon substrate by radio frequency (RF) capacitively coupled plasma in a deposition chamber. Spectroscopic ellipsometry was used to determine the layer thickness and its optical properties. The chemical structure of the layers was investigated by Fourier transform infrared spectroscopy and the mechanical properties were investigated by nanoindentation. The effect of power and self-bias (USB) on the chemical structure, mechanical and optical properties of the as-prepared layers, which are related to the crosslinking density, was investigated in the context of achieving low crosslinking density of the material. Low crosslinked plasma polymers were synthesized at a self-bias level of 1 V, which corresponds to an approximate RF power of 0,1 W. This material can be characterized by a density of 1, 2 g·cm-3 an elastic modulus of 4 GPa, a hardness of 0,04 GPa and a refractive index of 1.53 at 633 nm (He-Ne laser wavelength). Infrared spectroscopy confirmed that this plasma polymer is composed of a carbon network with fewer embedded silicon atoms and, in particular, the highest concentration of vinyl groups compared to plasma polymers prepared at higher powers.
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The preparation of Grafen by method CVD
Procházka, Pavel ; Kromka,, Alexander (referee) ; Mach, Jindřich (advisor)
This diploma thesis is mainly focused on the fabrication of graphene layers on the copper foil by the Chemical Vapor Deposition (CVD). For this purpose the high-temperature chamber for the production of the graphene was completed and fully automated. The production of the high area graphene on the copper foil was experimentally achieved. The Raman microscopy and X-ray photoelectron spectroscopy measurements proved that the produced graphene is mostly a monolayer. Graphene layer was transferred on non-conductive substrate.
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Preparation of graphene samples for experiments under UHV conditions
Mareček, David ; Mach, Jindřich (referee) ; Čechal, Jan (advisor)
This bachelor thesis deals with electrical conductivity of a graphene sample and preparation of a graphene field-effect transistor. In the theoretical part of the thesis, we describe electronic properties of graphene, preparation of graphene by CVD and its transfer to SiO_2. Experimental part of this thesis is focused on the preparation of a graphene field-effect transistor with long distance between Source and Drain electrodes. Thesis deals with a design of a chip expander for contact of graphene in UHV conditions. The last part describes measurement of dependency of graphene layer conductivity on the gate voltage with emphasis on the position of Dirac point during adjustments of the sample in UHV conditions.
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Influence of electron beam on graphene field effect transistors
Mareček, David ; Čech,, Vladimír (referee) ; Čechal, Jan (advisor)
This diploma thesis deals with electrical conductivity of a graphene sample, preparation of a graphene field-effect transistor and his irradiation by electron beam. In the theoretical part of the thesis, we describe electronic properties of graphene, preparation of graphene by CVD and its transfer to Si substrate with SiO_2 layer. Experimental part of this thesis is focused on the preparation of a graphene field-effect transistor for use in UHV conditions. Futher describes electron beam scanning over the transistor and creation of current maps of tranzistor. In the last part, the thesis deals with influence of electron beam on transport properties of graphene layer and doping of graphene layer by electron beam.
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Preparation and characterization of plasmonic graphene-copper nanostructures
Robešová, Magdaléna ; Pavelec,, Jiří (referee) ; Dvořák, Petr (advisor)
This diploma thesis deals with the study and preparation of graphene-copper nanostructures, which represent a new path in the research of plasmonic metasurfaces. This combination of copper with the unique properties of graphene could bring advancements in the quest for reliable copper plasmonic nanostructures. Alongside a literature review of previous scientific progress in this field, the nanostructures have been prepared using focused ion beam (FIB) and chemical vapor deposition (CVD) methods. Subsequently, the fabrication process underwent quality evaluation, and optical characterization was performed.
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Preparation of 2D materials in an ultrahigh vacuum electron microscope
Dymáček, Michal ; Bartošík, Miroslav (referee) ; Kolíbal, Miroslav (advisor)
This thesis is devoted to preparation of multilayer graphene and h-BN by CVD method. In the theoretical part of this thesis, both materials are introduced, as well as the CVD method and SEM. In the experimental part, the equipment and samples are described, as well as the computer codes, that were made within this work and used for analysis of taken images, and experiments, that were carried out. Utilizing in-situ analysis in ultra-high vacuum scanning electron microscope, the goal was to answer a question how is the multilayer graphene formed on the surface. Also, the first experiments of preparation of h-BN in this aparature were carried out.
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