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Low Energy Ion Scattering on Gold Structures
Joch, Vítězslav ; Čech, Vladimír (referee) ; Průša, Stanislav (advisor)
This diploma thesis deals with comparison of experimental and simulated low energy ion scattering spectra. There is a theoretical description of basic principles of low energy ion scattering and description of the spectrometer, which is situated at Institute of physical engineering. It is shown, how to prepare samples using the colloidal gold solution. The deposition of gold nanoparticles is characterized. The usage and meaning of time and energy spectra of low energy ion scattering is explained. There is also shown the effect of channeling in Si substrate.
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Characterization of 1-D Nanostructures by SPM Methods
Škoda, David ; Čech, Vladimír (referee) ; Pavlík, Jaroslav (referee) ; Dub, Petr (advisor)
The thesis is aimed at the characterization of carbon nanotubes and silver nanowires by Scanning Probe Microscopy, namely Scanning Tunneling Microscopy (STM), Atomic Force Microscopy (AFM), Conductive AFM (CAFM) and Scanning Near-Field Optical Microscopy (SNOM). Carbon nanotubes were analyzed by STM, AFM and CAFM microscopy. In a designed apparatus the silver nanowires were fabricated by template assisted deposition and were analyzed with respect to their geometry (AFM), local conductivity (CAFM) and optical properties (SNOM, microreflex spectroscopy). It was found that preferential type of carbon nanowires depends on the fabrication process. The measurements of local conductivity of the nanotubes revealed the similarity with the STM measurements. The AFM measurements of silver nanowires confirmed their growth inside the pores of polycarbonate template. Single nanowires exhibits the semiconducting behavior according to I--V measurement and localized plasmon resonances.
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Deposition and optical properties of thin films and layered structures by PECVD
Kucharčík, Jan ; Boušek, Jaroslav (referee) ; Čech, Vladimír (advisor)
Thesis in theoretical part is focused on the principle of spectroscopic ellipsometry and formation of thin films by plasma-enhanced chemical vapor deposition (PECVD). In the experimental part we describe the deposition system, ellipsometer and mathematical evaluation of ellipsometric data, materials used for film formation and processing of the samples. Single-layer and multilayer structures of polymeric materials were prepared. We revealed that the optical properties of thin films are independent of film thickness. We also described the effect of the effective power and deposition gas mixture on optical properties of thin films.
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Deposition of plasma polymer films
Malá, Michaela ; Brablec, Antonín (referee) ; Čech, Vladimír (advisor)
This bachelor thesis is focused on the characterization and preparation of thin polymer layers deposited by plasma-enhanced chemical vapor deposition on silicon wafer. The main part of the work is a literature review about the plasma polymerization and methods of characterization of thin polymer layers. In the experimental section were prepared thin layers of polymer from the monomer vapor of tetravinylsilane. Prepared thin films were characterized by microscopic and spectroscopic techniques. The physical and chemical properties of deposited films were studied with respect to the deposition conditions in low-temperature plasma.
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Adhesion of plasma polymer films deposited from tetravinylsilane monomer
Plichta, Tomáš ; Salyk, Ota (referee) ; Čech, Vladimír (advisor)
This bachelor thesis deals with the characterization of thin films of plasma polymers prepared from monomers of tetravinylsilane (TVS) and deposited on planar silicon substrates. Plasma enhanced chemical vapor deposition (PE CVD) was used as a method of thin films preparation. Three power series were prepared from pure TVS and two mixtures TVS with argon and oxygen. The main characterization methods were scratch tests and atomic force microscopy (AFM) is used to assess the adhesion degree of the layers and topography of scratches. To assess the characteristics and context the layer thickness was measured by spectroscopic ellipsometry (ELL) and elastic modulus using nanoindentation. The collected data were used to assess the reproducibility of the results with the regard to the purity of substrates and adhesion layers, depending on the deposition conditions and layers aging.
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Application of oxygen atomic beams
Mikerásek, Vojtěch ; Čech, Vladimír (referee) ; Mach, Jindřich (advisor)
V diplomové práci je popsán návrh, konstrukce a testování termálního zdroje svazku atomárního kyslíku, který je určen k růstu tenkých oxidových vrstev v podmínkách ultra vysokého vakua. První kapitola pojednává o teorii spjaté s termální disociací a tvorbou atomárních svazků. Dále jsou uvedeny hlavní typy zdrojů svazků atomárního kyslíku a jeho aplikace. Experimentální část je věnována samotnému návrhu zařízení, konstrukci a jeho složení. V poslední část je popsáno testování vlivu atomárního kyslíku na vznik oxidových vrstev (stechiometricky Ga2O3) na nanokapičkách Ga na křemíkovém substrátu připraveného molekulární svazkovou epitaxí. Chemické složení a morfologie připravených nanostruktur jsou zkoumány metodou XPS, SEM a TEM.
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Possibilities of preparing nanoelectronic devices on graphene using AFM
Lipták, Daniel ; Čech, Vladimír (referee) ; Bartošík, Miroslav (advisor)
V tejto diplomovej práci sme sa zamerali na štúdiu a prípravu nano-štruktúr na graféne pomocou lokálnej anodickej oxidácie. Naša pozornosť bola venovaná izolačným schopnostiam oxidovaného grafénu, ktorý bol študovaný pomocou mapovania povrchového napätia, využívaním sondovej mikroskopie Kelvinovej sily, a súčasným meraním toku nosičov nábojov. Získané výsledky poukazujú na zdvojnásobnenie odporu pri čiarovom oxidovom prerušení. Ku koncu, nano-zúženie s mikrometrovými rozmermi bolo vyrobené a študované pod rôznymi vlhkosťami, v rozmedzí 3% až 60%.
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Organosilicon plasma investigated by mass spectrometry
Moravanský, Martin ; Bránecký, Martin (referee) ; Čech, Vladimír (advisor)
This bachelor thesis deals with plasma-enhanced chemical vapor deposition (PECVD) and the use of mass spectrometry to monitor the processes in plasma during the deposition of thin film. Tetravinylsilane plasma was used in the process of forming a thin film on the silicon wafer. The background of the spectrometer, the residual gases in the plasma reactor at basic pressure were characterized and the plasma polymerization process was monitored. This process was monitored with increasing effective power (2-150 W). The obtained mass spectra were assigned and described in detail.
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Contamination in semiconductor fabrication
Fojtášková, Helena ; Salyk, Ota (referee) ; Čech, Vladimír (advisor)
This bachelor thesis deals with contamination in the production of semiconductor substrates. It focuses on the efficiency and optimization of wet cleaning processes for monocrystalline silicon and silicon carbide semiconductor wafers. The thesis includes a literature research in the field of semiconductor manufacturing, wafer contamination and wafer cleaning processes. The most commonly studied metal contaminants include iron, copper and nickel, due to their high diffusivity, and therefore these elements were chosen for the experimental part. In the experimental part, wafers were prepared by targeted contamination to verify the effectiveness of the cleaning processes. Contamination analysis was performed using the vapour phase decomposition method combined with inductively coupled plasma mass spectrometry (VPD-ICP-MS) for silicon wafers and total reflection X-ray fluorescence (TXRF) for silicon carbide wafers. Based on the measurement results, the efficiency of the washing processes was evaluated and a procedure for process optimization was recommended.
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Comparison of specialized actigraphs with wearable devices in quantitative sleep analysis
Čech, Vladimír ; Zvončák, Vojtěch (referee) ; Mikulec, Marek (advisor)
Actigraphy and smart wearable devices provide similar functionality in quantitative sleep analysis. This work aims to verify how common wearable devices stand in comparison with a specialized actigraph used in clinical practice. The actigraph used in this work was Geneactiv Original and it was used to compare the sleep analysis results of eleven commercially available devices. The measurements for nine of the measured devices lasted for one week. Two devices were measured for six days. During sleep, the device was worn on the same hand as the actigraph, and at the same time a sleep diary was kept, in which data on the time of lying down, the time of awakening and the number of awakenings per night were recorded. After a week of measurement, the data obtained from the actigraph were evaluated by software and then compared with the data provided by the second device. In this work, data of total sleep time, sleep onset latency, number of awakenings during the night and sleep efficiency are compared. Ten of the eleven devices measured higher total sleep time and higher sleep efficiency than the actigraph. These devices measured higher total sleep time by 1.21 % – 12.06 % and measured higher sleep efficiency by 2.86 % - 13.86 %. One device, namely Fossil Sport, measured lower total sleep time by 9.02 % and lower sleep efficiency by 9.13 %. Sleep onset latency was the most distinct parameter. Wearable devices measured higher sleep time by 86.72 % – 1225.95 %. Neither device nor actigraph could reliably determine the number of awakenings during the night unless it was a significant physical activity during the night. From the results of the work, it is not possible to say in general that all commercially available devices would be a reliable substitute for actigraphy.
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