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Electrical and optical properties of SiC single crystals
Brynza, Mykola ; Belas, Eduard (advisor)
Silicon carbide is a semiconductor with a wide bandgap of up to 3.2 eV and is capable of operating in extreme conditions, high temperature and high energy modes. This work focuses on the investigation of electrical and optical properties of monocrystalline SiC by various methods including Raman spectroscopy, volt-ampere characteristics, L-TCT and spectroscopic techniques. The adhesion of contacts and the influence of different contact materials on the ability to detect ionizing radiation are also studied to optimize the technology of preparation of quality SiC-based radiation detectors.
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Electrical and optical properties of SiC single crystals
Brynza, Mykola ; Belas, Eduard (advisor) ; Štekl, Ivan (referee)
Silicon carbide is a semiconductor with a wide bandgap of up to 3.2 eV and is capable of operating in extreme conditions, high temperature and high energy modes. This work focuses on the investigation of electrical and optical properties of monocrystalline SiC by various methods including Raman spectroscopy, volt-ampere characteristics, L-TCT and spectroscopic techniques. The adhesion of contacts and the influence of different contact materials on the ability to detect ionizing radiation are also studied to optimize the technology of preparation of quality SiC-based radiation detectors.
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Graphene on SiC as a substrate for molecular self-assembly systems
Černá, Lenka ; Průša, Stanislav (referee) ; Procházka, Pavel (advisor)
This bachelor thesis deals with the fabrication and characterization of metal-organic frameworks formed by self-assembly mechanism of metal atoms (Fe) and organic molecules (tetracyanoquinodimethane, TCNQ) on a graphene surface. The fabrication of self-assembled structures has been performed on epitaxial graphene on SiC(0001) substrate. The deposition of metal-organic networks, as well as subsequent surface characterization by low-energy electron microscopy (LEEM) scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS), were performed under ultra-high vacuum conditions.
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Structure defects in SiC radiation detectors
Zetek, Matyáš ; Belas, Eduard (advisor)
Silicon carbide (SiC), is a wide band gap (2.4 eV < Eg < 3.3 eV) semiconducting material well known for its potential applications in high-temperature, high-power, high-frequency or hard radiation resistant devices. In this thesis, we are broadening elementary knowledge about this material. We identify energy levels in the material, using Photo-Hall effect spectroscopy supported by the temperature dependency of classic Hall effect measurement and temperature dependent photoluminescence. This knowledge is essential to allow SiC application as a radiation detector.
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Electrical and optical properties of SiC single crystals
Brynza, Mykola ; Belas, Eduard (advisor) ; Štekl, Ivan (referee)
Silicon carbide is a semiconductor with a wide bandgap of up to 3.2 eV and is capable of operating in extreme conditions, high temperature and high energy modes. This work focuses on the investigation of electrical and optical properties of monocrystalline SiC by various methods including Raman spectroscopy, volt-ampere characteristics, L-TCT and spectroscopic techniques. The adhesion of contacts and the influence of different contact materials on the ability to detect ionizing radiation are also studied to optimize the technology of preparation of quality SiC-based radiation detectors.
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Light ceramic materials for ballistic protection
Greguš, Peter ; Pouchlý, Václav (referee) ; Salamon, David (advisor)
This thesis gives a comprehensive characterization of lightweight non-oxide ceramic materials for ballistic applications, an overview of production technologies and processing of boron carbide B4C and its ceramic-based composites. A framework for evaluating the ballistic resistance of the material based on mechanical properties is shown there. It can be used in experiments without normalized equipment. The experiments including B4C + Si, B4C + Ti composites, and application of Spark plasma sintering (SPS) were designed according to outputs from the theoretical part. The volume fractions of Si, Ti dopants were optimized based on ongoing chemical reactions during sintering. The obtained samples were subjects of mechanical testing which results were compared to identify the ideal ratio of matrix and reinforcement. As the best suited material for ballistic protection, B4C + 1,0 obj. % reaches these values of parameters; hardness = 3502 ± 122 HV1; fracture toughness KIC = 2,97 ± 0,03 MPam^0,5.
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Electroerosion wire cutting of technical ceramics
Habovštiaková, Mária ; Mouralová, Kateřina (referee) ; Osička, Karel (advisor)
The presented diploma thesis deals with the issue of wire electrical discharge machining of SiSiC ceramics. The first part explains the principles of electrical discharge machining, describes the WEDM technology and presents the properties of the advanced ceramics. The second part consists of a detailed analysis of the cutting process of eighteen samples obtained with systematically changing process parameters. Based on the obtained results from EDX analysis, SEM electron microscopy and topography there was performed an analysis of the influence of process parameters on the cutting speed, surface roughness, kerf width and number of wire breaks with usage of the selected brass cutting wire. From the evaluated results it was possible to select a combination of parameters that ensured a stable machining process.
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Structure defects in SiC radiation detectors
Zetek, Matyáš ; Belas, Eduard (advisor)
Silicon carbide (SiC), is a wide band gap (2.4 eV < Eg < 3.3 eV) semiconducting material well known for its potential applications in high-temperature, high-power, high-frequency or hard radiation resistant devices. In this thesis, we are broadening elementary knowledge about this material. We identify energy levels in the material, using Photo-Hall effect spectroscopy supported by the temperature dependency of classic Hall effect measurement and temperature dependent photoluminescence. This knowledge is essential to allow SiC application as a radiation detector.
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Role of hydrogen during growth of epitaxial graphene on SiC
Sýkora, Petr ; Kunc, Jan (advisor) ; Čechal, Jan (referee)
This work is focused on preparation of graphene by epitaxial growth on silicon face of silicon carbide. In the introduction, the interesting properties of graphene are briefly described, and its possible applications are mentioned. Subsequently, the methods of preparation are discussed with an emphasis on epitaxial growth and the role of hydrogen on the process itself. Further, the possible ways of measuring graphene samples are explained and three of them are analyzed in more detail - Raman spectroscopy, atomic force microscopy, and Hall effect measurement. The experiment itself is focused on the effect of argon-hydrogen atmosphere on the growth of graphene. 1
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Structure defects in SiC radiation detectors
Zetek, Matyáš ; Belas, Eduard (advisor) ; Hazdra, Pavel (referee)
Silicon carbide (SiC), is a wide band gap (2.4 eV < Eg < 3.3 eV) semiconducting material well known for its potential applications in high-temperature, high-power, high-frequency or hard radiation resistant devices. In this thesis, we are broadening elementary knowledge about this material. We identify energy levels in the material, using Photo-Hall effect spectroscopy supported by the temperature dependency of classic Hall effect measurement and temperature dependent photoluminescence. This knowledge is essential to allow SiC application as a radiation detector.
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