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Scanning probe microscopy scanner with high resonant frequency
Krupa, Matyáš ; Dostál, Zbyněk (referee) ; Pavera, Michal (advisor)
The thesis deals with the design of the scanning probe microscopy scanner with a higher resonant frequency. The first part of the thesis is focused on theory as the principle of atomic force microscopy, function of the scanner and its properties. The second part describes the gradual development of a new microscope. The mechanical simulations used to determine the properties of scanners are introduced first. Furthermore, the thesis deals with the design for the x, y axis and then also for the z axis. In conclusion, the final design of a three-axis scanner with a higher resonant frequency is presented.
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Self-sensing SPM probes for measuring electrical properties of materials
Očkovič, Adam ; Vařeka, Karel (referee) ; Pavera, Michal (advisor)
The bachelor's thesis is focused on the modification of probes with an integrated sensor usable for measuring conductivity characteristics of surfaces in atomic force microscopy. The first part presents the theory concerning atomic force microscopy, conductivity measurement and deposition using an ion beam. Furthermore, the method of production and limitation of the use of electrically conductive probes with optically read deflection is described. The practical part presents the main problems of probes with integrated sensors in conductivity measurements. Furthermore, the modification of the probes themselves, the measurements made with these probes and suggestions for improving the properties of the probes are described.
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Aplication of SPM in study and modification of ultrathin films Pt, Co and graphene
Lišková, Zuzana ; Červenka,, Jiří (referee) ; Bartošík, Miroslav (advisor)
This diploma thesis deals with the preparation of the very thin films and their investigation by scanning probe microscopy methods. The ultrathin films of Pt on Pt(111) were created by pulsed laser deposition and the ultrathin films of Co on Pt(111) were deposited by thermal evaporation. The coverage of the substrate was much smaller than one monolayer (in order of hundredths of monolayer). The nucleation theory was verified by these experiments using so-called Onset method. Further graphene sheets were prepared on layer of Si/SiO2 by the mechanical exfoliation from the graphite crystal. The fabricated graphene sheets were studied by micro-Raman spectroscopy, microreflectometry, atomic force microscopy and similar techniques. These methods proved the thinnest graphite layers were consisted of two graphene monolayers.
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Local characterization of electronic devices
Müller, Pavel ; Škarvada, Pavel (referee) ; Tománek, Pavel (advisor)
The development of micro and nanoelectronics and nanophotonics needs novel characterization techniques to ensure higher quality of designed devices. The thesis describes a use of Scanning Near-field Optical Microscopy (SNOM) in dimensional control and in local investigation of diverse physical parameters. As example of its potential, the correlation between object topography and reflection measurement of capacitors is shown.
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Preparation and analysis of nanostructures in UHV conditions
Gloss, Jonáš ; Spousta, Jiří (referee) ; Mach, Jindřich (advisor)
Cílem této bakalářské práce bylo skoumání přípravy a analýzy nanostruktur v podmínkách vysokého vakua (VV). Teoretická část klade důraz na gallium nitridové (GaN) nanostruktury. Ty pak byly analyzovány rastrovacím tunelovacím mikroskopem (RTM). Aby bylo možné analyzovat připravené vzorky ve VV RTM, bylo provedeno elektrochemické leptání wolfrámového drátu. Tato práce zhrnuje postup k vytvoření wolfrámových hrotů pro RTM. Kapitola o výrobě wolfrámových hrotů zahrnuje popis princípu elektrochemického leptání. Obrázky vyleptaných hrotů byly provedeny pomocí rastrovacího elektronového mikroskopu. Zaostřování hrotů pak bylo vykonáno fokusovaným iontovým svazkem. V této práci je také představena metoda pro opětovné ostření RTM hrotů elektronovým svazkem, vykonávaná in-situ. Bylo dokázáno, že je možné rutinně obdržet wolfrámové hroty s poloměrem křivosti rádovo v nanometrech.
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Correlative measurement of cathodoluminescence using SEM and SPM techniques
Černek, Ondrej ; Knápek, Alexandr (referee) ; Spousta, Jiří (advisor)
The diploma thesis deals with the combined use of SEM and SPM techniques using optical fiber, which is used to collect the cathodoluminescent signal in close proximity to the sample. The thesis also includes a research section, which lists description of CPEM technique, the techniques used to modify the optical fiber, theoretical introduction to cathodoluminescence and techniques used to measure it. The practical part discusses the obtained measurement results and the problems that occurred in the process of modification of the optical fiber, its use as an SPM probe and in the measurement of cathodoluminescence active materials.
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Correlates finding of heart rate changes in fMRI data
Jurečková, Kateřina ; Gajdoš, Martin (referee) ; Bartoň, Marek (advisor)
This master’s thesis deals with problematic of correlates finding of heart rate changes in fMRI data. The first part describes principle of fMRI, creation of BOLD signal, data acquisition, their pre-processing and analysis. The next part describes heart rate variability and its impact on fMRI data. The following section is dedicated to pre-processing of heart rate time series to the form, which can be used in correlates finding of heart rate variability and fMRI data with generalized linear model. The process of statistical testing and its result with discussion can be found in the last part of this thesis.
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A comparison of effective and functional connectivity methods in fMRI
Gajdoš, Martin ; Schwarz, Daniel (referee) ; Jan, Jiří (advisor)
Functional magnetic resonance imaging (fMRI) is recent important method, used in neuroimaging. The aim of this thesis is to develop software tool for comparison of two methods for functional and effective connectivity estimation. In this thesis are described the basics of magnetic resonance imaging, fMRI, basic terms of fMRI experiments and generally are described methods of functional and effective connectivity. Then are more detailed mentioned methods of dynamic causal modeling (DCM), Granger causal modeling (GCM) and independent component analysis (ICA). Practical implementation of DCM in toolbox SMP and ICA in toolbox GIFT is also mentioned. In purpose to describe behavior of DCM and GCM in dependence on several parameters are performed Monte Carlo simulations. Then the concept and realization of software tool for simulating connectivity and comparison of DCM and GCM are described. Finally results of DCM and GCM comparison and results of Monte Carlo simulations are discussed.
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Non-linear character of optical environment
Žáček, Martin ; Míča, Ivan (referee) ; Přinosil, Jiří (advisor)
This paper describes theoretical and application options of nonlinear effects in optical medium. Optical medium means fiber optics, because the fiber is the most employed optical medium at these days. Basic statements of this work are theoretical information with mathematical and physical expressions. These expressions defines nonlinear medium and effects which are founded here. These effects are split to second and third orders. Nonlinear effects of second orders are Second-harmonic Generation, Three-wave Mixing process. Nonlinear effects third orders are Third-harmonic Generation, Self-phase Modulation, Cross-phase Modulation, Four-wave Mixing and Degenerative Four-wave Mixing process. These effects are extended by scattering effects – Brillouin’s and Raman‘s Scattering. The next point discuss about optical communication system DWDM. DWDM uses dense wavelength multiplexing. Nonlinear effects have a few negative influences on these systems. There are requests for high bandwidth and communication speed. FWM and XPM limit these requests. They can invoke cross-talks. We support theoretical information with application examples and simulations at the end of this work. We use OptSim v.4.0 program. We are simulate FWM and XPM effect in depend on chromatical dispersion and power.
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Study of Properties of Metallic Thin Films and Nanostructures Using Scanning Probe Microscopy
Doupal, Antonín ; Fejfar, Antonín (referee) ; Kalousek, Radek (advisor)
This diploma thesis is focused on investigation of metallic thin films and nanostructures using scanning probe microscopy. Magnetic properties of these objects are studied by magnetic force microscopy, which is modification of scanning probe microscopy. In the theoretical part basic principles of scanning probe microscopy and magnetic force microscopy are summarized, and also principle of creation of magnetic domains and some special properties of ferromagnetic and antiferromagnetic materials. Further, two techniques of fabricating nanostructures are described. Experimental part is focused on imaging and simulating of magnetic domains. Further, exchange bias is revealed. This phenomenon is present in systems composed from ferromagnetic and antiferromagnetic materials. One part of this diploma thesis is also focused on discussion of problems with magnetic force microscopy.
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