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Functional organic-inorganic nanostructures
Kelíšek, Petr ; Zmeškal, Oldřich (referee) ; Čech, Vladimír (advisor)
Diploma thesis deals with preparation of multilayered organic-inorganic nanostructures via PECVD technology and analysis of optical properties of these layers by spectroscopic ellipsometry. The theoretical part handles the definition of thin layers, layered and gradient nanostructures, plasma enhanced chemical vapor deposition and principles of spectroscopic ellipsometry. In the experimental part, used materials and chemicals are described, afterwards follow a complete description of the apparatus used for sample preparation and a description of the sample preparation procedure. The results part consists of methodology of preparing material models necessary for ellipsometric measurements and evaluation of optical properties of deposited nanolayers.
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Study of optoelectrical properties of organic semiconductor thin film layers of phtalocyanines
Miklíková, Zdeňka ; Vala, Martin (referee) ; Zmeškal, Oldřich (advisor)
Diploma thesis is focused on the study of optoelectric properties of thin layers of organic materials based on phthalocyanines, which can be used as an active layer of photovoltaic cells. Especially are studied the properties of the thin active layers of PdPc and PdPc + IL on the glass or ceramic substrates with aluminium contact, which are prepared by material printing here. On the prepared samples were first measured current-voltage characteristics in the dark and in the light and then were measured impedance spectrums in the dark. The received results will be used to improve the properties and structures of photovoltaic cells.
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Study of thin transparent films properties
Schmiedová, Veronika ; Veselý, Michal (referee) ; Zmeškal, Oldřich (advisor)
The main aim of this bachelor´s thesis is a study of thin transparent layers of organic materials (PPV, P3HT, TiO2, DPP). The theoretical part describe the methods of quality examinations of their surface, mostly the use of optical and interference microscopy. For elaboration of data was used the image analysis via HarFA program. Thickness of layer and the index of refraction was provided by interference microscope. From the interference images was identified the amplitude of groove for various values of treshold, but mainly the interface inhomogenity of groove, which proofs the surface inhomogenity of samples. For the images taken by the optical microscope were allocated the average errors (but also errors of superior sorts) defining the surface inhomogenities of samples. The conlusion of this study compare the results of both methods.
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Physical-chemical property characterisation of thin reflective layers on silicon substrates
Rozsívalová, Zdeňka ; Studýnka, Jan (referee) ; Krčma, František (advisor)
This thesis deals with surface analysis and characterization of optical features of thin films created by hexamethyldisiloxane (HMDSO) plasma polymerization on silicon wafers. The RF plasma industrial deposition equipment was used for the thin layers formation. These thin films serve as protective coatings on the reflective layer in the car light or solar panels. Theoretic part gives basic information about plasma, its occurrence, features, diagnostics and applications. Thin layers, their production and characterization are discussed here, too. Theoretic description of monomer material (including the group of other organosilicones) is also presented here. The FTIR spectroscopy and elipsometry are mentioned as the main methods for thin films characterisation. Because material during its practical use degrades due to external conditions, the influence of them on the thin layer properties is studied using the accelerated aging of created films. Industrial deposition chamber AluMet 1800V made by Leybold Optics, Ltd. installed in Zlin Precision company was used for the thin films production. Thin films were created under different conditions that were selelected near to the real conditions used in technology. Various applied powers (2-5 kW) were used for the deposition under different monomer flows. Further, the influence of oxygen addition on the created film properties was investigated. The deposition process was monitored by optical emission spectroscopy. The spectrometer Jobin Yvon Triax 320 with CCD detector was used. The selected part from every samples set was exposed by UV radiation (48 hours at radiation density of 0.68 W/m2 at 340 nm) to simulate the probable conditions during the layers real use. The surface properties were investigated by measurement of reflected light spectral intensity in the visible range at different angles. The angle between incident and reflected beam was varied in the interval of 40 - 150° with 10° step. The influence of sample preparation conditions as well as their aging effect was studied at the selected angles. Spectral reflectance doesn´t depend significantly on applied discharge power and oxygen addition. The significant shift of reflectance into the red part of spectrum was observed at UV exposed samples more or less independently on the applied discharge power of monomer flow rate. Addition of oxygen during the deposition suppresses this effec significantly. Characterization of thin layer structure was done by FTIR spectroscopy. No significant changes were observed in the structure at different discharge powers of monomer flow rates except total absorption intensities that are proportional to the layr thickness. The oxygen addition, of course, changes the structure significantly. These results are only preliminary because the layers were very thin (deposition conditions were near to the common process standard) and thus the signal/noise ratio was relatively low.
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Determination of elastic modulus of thin layer - numerical study of microcompressive test and the bulge test
Petráčková, Klára ; Pokorný, Pavel (referee) ; Náhlík, Luboš (advisor)
Determination of mechanical properties of very thin films is rather difficult task as all of currently using testing techniques have some weakness. This master’s thesis deals with microcompressive test and bulge test. Finite element simulations of the two methods were carried out in order to better understanding of experimental record. Microcompression combines the sample preparation with the use of focused ion beam (FIB) with a compression test carried out using nanoindenter. Cylindrical specimens (pillars) were prepared from Al film deposited on Si substrate using FIB. Experimentally measured data on pillars needs correction to obtain undistorted material properties of Al thin film. A necessary correction using FE modeling is suggested in the thesis. Second part of the work is focused on modeling of bulge test. Pressure is applied on freestanding SiNx film while deflection of the film is measured. Stress state in the film is biaxial making determination of mechanical properties of the film more complicated. The goal is to present how to model the whole problem. In addition, preparation of the specimens was simulated to estimate residual stress in the film. The paper contributes to a better characterization of very thin surface layers and determination of their mechanical properties.
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Compressive testing of pillars: numerical study
Petráčková, Klára ; Zouhar, Michal (referee) ; Náhlík, Luboš (advisor)
Determination of mechanical properties of thin films, which are used e.g. in electronics, is not simple due to the required very sophisticated equipments. Also the interpretation of results is rather difficult. This bachelor’s thesis is focused on determination of important factors which affect the microcompressive testing results. For microcompressive testing, the pillars made from studied thin film attached by the bottom to a substrate are used. There can be another thin interlayer between studied film and the substrate. The pillar is made by focused ion beam (FIB). Pillar is loaded by a nanoindenter with flat tip while the deformation response is measured. The goal of the thesis is numerical simulation (using the Finite Element Method) of the microcompressive testing and determination of individual specific geometric factors of tested pillars on Young’s modulus of the thin film. Data from microcompressive testing of aluminium thin film attached to silicon substrate with tungsten interlayer were available for numerical simulation. We have estimated influence of specific pillar geometry on data using compressive testing and improved evaluation of Young’s modulus. We have presented a recommendation for more accurate evaluation of Young’s modulus determined from experimental data involving inaccuracy following the pillar shape. The results and methods presented in this thesis can be useful in future development of compressive testing technique for determination of mechanical properties of metal thin films.
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Fabrication and characterization of tungsten trioxide photoanodes
Hesková, Helena ; Králová,, Marcela (referee) ; Dzik, Petr (advisor)
This work deals with the optimization of the preparation process of WO3 photoanodes nad their characterization. For compositions were prepared, which were applied to a substrate via spin-coating process and subsequently annealed at 450 °C. The length of milling of precursor particles contained in the coating formulations determined properties of deposited layers. were examined for. The additivity of the individual compositions was also observed. The structure of the layers was observed by optical microscopy and scanning electron microscopy (SEM), their composition by the X-ray diffraction (XRD) and their thickness and surface roughness was defined by contact profilometry. Photoelectrochemical properties of the prepared layers were also investigated by linear voltametry and chronoamperometry.
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Optical properties of protective emulsions
Valasová, Denisa ; Veselý, Michal (referee) ; Zmeškal, Oldřich (advisor)
This bachelor´s thesis is aimed to the study of optical properties of protective commercially available emulsions. Chosen emulsions should be responsible for sun protection. They also may be used in cosmetic industry. In the beginning of the thesis, there are defined theoretical features of emulsions and their interaction with UV radiation. Methods which are used to describe optical properties could be found in this section too. The optical properties were measured in thin layer films, in order to simulate emulsions applied on the human skin. UV-VIS spectrophotometry was mainly used to study the optical properties. The obtained results could serve, purely hypothetically, like sun protective tests of chosen emulsions.
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Study of thin films of molecular nano-magnets prepared by Langmuir-Blodgett technique and drafting of an adapted Langmuir trough
Vaverka, Jan ; Neugebauer, Petr (referee) ; Novák, Jiří (advisor)
This diploma thesis focuses on studies of deposition of molecular nanomagnets doubledecker dysporsium phtalocyanine via Langmuir-Blodgett method. The thesis describes the influence of deposition parameters on structure of deposited molecular layer of doubledecker dysporsium phtalocyanine. The prepared molecular layers are analysed by X-ray reflectivity and Atomic force microscopy. Moreover, the proposal of structural changes of KSV Minimicro instrument, used for Langmuir Blodgett deposition, is described. The intended result is Langmuir trough of bigger dimensions than the recent one, which would enable to distribute molecular layers numbering about magnitude of hundreds.
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