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Hydrogen quantification by electron spectroscopy
Endstrasser, Zdeněk ; Polčák, Josef (referee) ; Čechal, Jan (advisor)
The absence of hydrogen in the photoelectron spectrum remains one of the greatest limitations of X-ray photoelectron spectroscopy. The main aim of this work is therefore to determine the concentration of hydrogen atoms in the near surface region of a sample. The REELS electron spectroscopic method based on quasi-elastic electron scattering is used for this purpose. The choice of this method was given mainly by the fact that the photoelectron spectrometers has an electron source in the basic equipment, so there is no requirement to purchase additional equipment. In our case, measurements were realized using the AXIS Supra photoelectron spectrometer in CEITEC laboratories. We were primarily focused on the study of polymer samples in this work. The gus cluster ion source was used for sputter cleaning of the sample surface. Then the XPS and REELS measurements were performed on such cleaned samples. The obtained data were subsequently evaluated, and the results discussed. The most important output of this work was to develop the methodology of detection and quantification of hydrogen atoms. However, the theoretical description of the methods used, and the appreciation of critical aspects associated with the use of the REELS method are also embraced. In particular, the effect of sample charging and electron dose on measurement results is discussed.
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Morphology study of ultra thin layers by XPS analysis of multiple peaks of a single element
Pokorný, David ; Šik, Ondřej (referee) ; Polčák, Josef (advisor)
This diploma thesis deals with methodology of thin film thickness determination using X-ray radiation of silver anode which provides radiation with energy of 2984,3 eV. This energy is twice as high as the standard aluminium radiation which allows a measurement of new photoelectron lines with higher bonding energy and it also provides thanks to the higher photoelectron energy greater information depth. In order to get the right results it was necessary to calibrate the spectrometer Kratos Axis Supra in the silver anode mode first and found out the form of the transmission function. The determination of the thickness of the thin layer was demonstrated by the comparation of the ratio of different photoelectron lines intensities with the theoretical model. For that purpose was specifically used the Si 1s and Si 2p peak bound in the substrate in the Si-Si bonding or in the thin oxid layer in the Si-O bonding. The results show that for thin SiO2/Si film thickness determination is the best to use the intensity ratio of only one photoelectron line. A silver anode however provides greater information depth.
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Analysis of Trench Insulated Gate Bipolar Transistors
Karlovský, Juraj ; Polčák, Josef (referee) ; Bábor, Petr (advisor)
This thesis is focused on the selection and optimalization of suitable analytical methods for study of TIGBT (Trench Insulated Gate Bipolar Transistor) structures with a use of methods, that depict material composition of the studied sample. The theoretical part contain explana-tions of the analytical methods used for measurements and basic principle of operation of an TIGBT transistor. The practical part contain the methodic of measurements and the evaluation of the obtained data and design of optimal procedures in done experiments.
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Surface Analysis by Photoelectrons – Computer Control of Experiments
Polčák, Josef ; Zemek, Josef (referee) ; Cháb, Vladimír (referee) ; Šikola, Tomáš (advisor)
Doctoral thesis is dealing with the methods for analysis of surfaces by photoelectrons being emitted by X-ray radiation. The methods are: X-ray Photoelectron Spectroscopy - XPS, Angle-resolved XPS - ARXPS and X-ray Photoelectron Diffraction - XPD. The work is especially focused on a method of ARXPS, which is used for the depth compositional analysis of sample surfaces. To obtain an information about the depth composition from the measured ARXPS spectra, a calculation software in the Matlab environment has been developed. The software has been tested both for simulated and real sample data. For an experimental implementation of these methods, a complete manipulation system has been developed. It ensures the transport of samples inside a vacuum apparatus and the experiment itself. The system is controlled mainly by a software and enables to run the experiments automatically.
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Upgrade of the UHV manipulator for SIMS and LEIS methods
Dao, Tomáš ; Polčák, Josef (referee) ; Bábor, Petr (advisor)
This bachelor’s thesis deals with the design and the construction of the manipulator, which operates under ultra high vacuum. In the first section, the original design and realization of the manipulator with six motion axis is introduced. Second section deals with the modifications of the manipulator. Advantages and disadvantages of the design are discussed and a new design of the manipulator, based on the experience from manipulator operation, is projected. Section is mainly focused on the design of the sample rotation using a stepper motor working in the ultra high vacuum. The new Faraday cup was also designed and tested. The last section contains the LEIS structural analysis measurement using the manipulator.
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Optimization of thermal dissociation atomic hydrogen source for use SEM
Melichárek, Václav ; Polčák, Josef (referee) ; Mach, Jindřich (advisor)
The focus of this bachelor's thesis is the optimization of a thermal dissociation monoatomic hydrogen source. The project entailed the design and construction of a new control electronics for the thermal dissociation source, because the source has been powered using universal laboratory power supplies until now. The thesis begins with a brief introduction into the interaction of graphene with monoatomic hydrogen, the operational principle and construction of the monoatomic hydrogen source. Furthermore, the requirements on the design of the electronics are specified. A more detailed analysis of possible solutions, and the selection of the optimal solution were also conducted. The practical part discusses the conceptual designs in detail and describes the selection of the optimal solution. It follows by elaborating on the implementation of the control electronics in detail, its design and construction, and the electrical circuit in particular.
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SiO2 etching by Si deposition
Pokorný, David ; Bábor, Petr (referee) ; Polčák, Josef (advisor)
This bachelor thesis deals with one of the most interesting reactions taking place in the solid phase in UHV conditions and that is decomposition of SiO2 according to the equation Si + SiO2 = 2SiO. It was used the previously untested procedure - providing Si atoms not from substrate, but by direct deposition on the surface of the oxide. As a source of silicon atoms was used effusion cell. Deposition of silicon on SiO2 substrate was used at room temperature and at elevated temperature to clarify the principle of this reaction. The activation energy and temperature dependence of the reaction rate was determined. It was also verified the possibility of etching SiO2 by Si deposition in UHV conditions. The prepared samples were examined by x-ray photoelectron spectroscopy and atomic force microscopy.
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Study of chemical cleaning of surfaces by LEIS method
Staněk, Jan ; Polčák, Josef (referee) ; Bábor, Petr (advisor)
This thesis deal with studying chemical etched surfaces of cadmium telluride crystals (CdTe crystals) by low-energy ion scattering spectroscopy (LEIS method). In the theoretical part, there is description of physical essence of LEIS method, including experimental arrangement of Qtac100 instrument, on which the experiment is measured. The LEIS method is also compared with X-ray photoelectron spectroscopy (XPS). There is summary of properties and structure of CdTe crystals including principle of X-ray detectors, which are the primary use of the crystals. In experimental part there is a description of measuring process, starting with a calibration measurement, ongoing with a chemical etching and ending with a surface analysis. There are examples of LEIS spectra with comments and interpretation including comparison with XPS data.
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Passivation of germanium surface using ALD
Kuba, Jakub ; Polčák, Josef (referee) ; Kolíbal, Miroslav (advisor)
The thesis deals with passivation of germanium surfaces by chemical etching and atomic layer deposition (ALD). Attention was paid to the rate of oxidation of germanium surfaces after selected passivation methods and the composition of the germanium suboxides. In the thesis selected methods for germanium oxide removal are reviewed and a brief description of the methods used for analysis (XPS) and thin film deposition (ALD) is given.
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Morphology study of ultra thin layers by XPS analysis of multiple peaks of a single element
Pokorný, David ; Šik, Ondřej (referee) ; Polčák, Josef (advisor)
This diploma thesis deals with methodology of thin film thickness determination using X-ray radiation of silver anode which provides radiation with energy of 2984,3 eV. This energy is twice as high as the standard aluminium radiation which allows a measurement of new photoelectron lines with higher bonding energy and it also provides thanks to the higher photoelectron energy greater information depth. In order to get the right results it was necessary to calibrate the spectrometer Kratos Axis Supra in the silver anode mode first and found out the form of the transmission function. The determination of the thickness of the thin layer was demonstrated by the comparation of the ratio of different photoelectron lines intensities with the theoretical model. For that purpose was specifically used the Si 1s and Si 2p peak bound in the substrate in the Si-Si bonding or in the thin oxid layer in the Si-O bonding. The results show that for thin SiO2/Si film thickness determination is the best to use the intensity ratio of only one photoelectron line. A silver anode however provides greater information depth.
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