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CREATION OF NANOSTRUCTURES ON SURFACES OF SOLID MATTER USING HYBRID METHODS
Rudolfová, Zdena ; Mikulík, Petr (referee) ; Horová, Ivana (referee) ; Kolíbal, Miroslav (advisor)
This thesis deals with the study of GaAs surface properties and with methodology of metal (mainly gold) nanoparticles deposition on GaAs substrate. GaAs has complicated surface oxides structure, which are very reactive when exposed to various chemicals (both acids and alkalines) and therefore they change GaAs surface properties. That is why the study of this properties is crucial for understanding of GaAs surface reactions on metal particles colloidal solution, from which the nanoparticles are deposited on the surface. The possibilites of GaAs surface etching and passivation are discussed. These should lead to surface stability enhancement during colloidal nanoparticles deposition. There was also studied the influence of adhesive polymer monolayer grown on GaAs substrate to the amount of nanoparticles deposited to the surface after substrate immersion into colloidal solution. This thesis concentrates on analyzing of methods, how the gold colloidal nanoparticles can be deposited selectivelly, only to defined areas. The areas were defined using charged particle beam.
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Terahertz conductivity of charge carriers in semiconductors
Hendrych, Erik ; Kužel, Petr (advisor) ; Nádvorník, Lukáš (referee)
In this thesis, we investigate the conductivity spectra of samples of weakly doped gal- lium arsenide in the terahertz region as a function of temperature. These are silicon-doped gallium arsenide of type N and zinc-doped gallium arsenide of type P. The temperature dependence in the terahertz region for these materials has not yet been described in the literature. We observe conductivity maxima corresponding to the admixture energies in the forbidden band. We use the Drude-Lorentz model to process the data. We achieve a good fit of the measured data. The carrier concentration at room temperature corre- sponds to the nominal value. The relaxation time and high-frequency permittivity match the tabulated values. The oscillator frequency for the N type approximately matches the admixture energy. For the P type, this value is outside the measured range and only the rise to this maximum is seen. 1
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Structural Analysis Of Gaas-Based Pv Cells After Ionizing Irradiation
Papež, Nikola
Morphology and structural analysis of photovoltaic cells based on GaAs before and after high dose gamma radiation of 500 kGy was investigated. Cobalt-60 emitter was used as the synthetic radioactive isotope. This radioactive form of cobalt is commonly used for space instruments and devices testing. Atomic force microscopy (AFM) was used to study the morphology and roughness differences. Cross-sectional investigation using transmission detector to thin layers observing was performed. Also, with use of sputtering system of Secondary Ion Mass Spectroscopy (SIMS) a detailed molecular and elemental information about the surface top layers was showed. Another molecular and structural changes in the top layers using two optical methods of Raman spectroscopy and spectrophotometry were also identified.
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Law aspect of cloud computing: GaaS as a new form of cloud servis
Janda, Petr ; Holcová, Irena (advisor) ; Žikovská, Petra (referee)
Cloud gaming, also known as Gaming as a Service or GaaS is a quickly developing service with significant economic potential. Author follows this trend and focuses on the topic of providing videogames as a service through cloud environment. The goal of this work was to analyse and describe legal relations between authors of videogames, providers, and users of GaaS in the context of Czech copyright and to present practical consequences of these relations, mainly in contrast to SaaS. Firstly, the reader is acquainted with basic aspects of videogames with emphasis on classification and description of videogames and its parts, i.e. computer program and other elements, as a work of authorship. Author describes possible theoretical views on the protection of audio-visual components of videogames. It is then pointed out that no satisfactory classification of video game as a singular work of authorship can be provided under the Czech Copyright Act. Videogame legislation is also proposed. Subject of the second section of this thesis is cloud gaming technology. This segment is written as to be understandable even for non-experts in the field. At first basic types of cloud services are presented. Then, the technology behind cloud gaming is described, along with business models one can come across nowadays....
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Charge transport in semiconducting radiation detectors
Pipek, Jindřich ; Belas, Eduard (advisor)
This thesis is focused on study of charge transport in semiconducting radiation detectors. Theoretical calculations of current waveforms based on continuity equation and drift-diffusion equation are done. Useful approximations of current waveforms for detector with shallow electron trap are discussed. Monte Carlo simulation of the current waveforms is proposed and applied to fit experimental current waveforms measured using laser-induced transient current technique and for evaluation of charge transport parameters of the detector such as electric field profile, trapping and detrapping time of traps, drift mobility and other parameters. Detectors prepared from semi-insulating GaAs and CdZnTe single crystals are tested using electrical, spectroscopic and optical characterization techniques.
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Charge transport in semiconducting radiation detectors
Pipek, Jindřich ; Belas, Eduard (advisor)
This thesis is focused on study of charge transport in semiconducting radiation detectors. Theoretical calculations of current waveforms based on continuity equation and drift-diffusion equation are done. Useful approximations of current waveforms for detector with shallow electron trap are discussed. Monte Carlo simulation of the current waveforms is proposed and applied to fit experimental current waveforms measured using laser-induced transient current technique and for evaluation of charge transport parameters of the detector such as electric field profile, trapping and detrapping time of traps, drift mobility and other parameters. Detectors prepared from semi-insulating GaAs and CdZnTe single crystals are tested using electrical, spectroscopic and optical characterization techniques.
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Characteristics Of Gallium Arsenide Solar Cellsat High Temperature
Papež, Nikola
This article reviews a work on processing of gallium arsenide (GaAs) solar cells. The performance of the cells before and after 300 _x000E_C thermal processing was correlated with topography identified by optical camera, atomic force microscope (AFM) and scanning electron microscope (SEM). Experiment indicates insignificant changes in topography of GaAs solar cells, but electrical characteristics show an excellent resistance of the samples to processing temperature.
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Morphological Structure Of Solar Cells Based On
Silicon And Gallium Arsenide After Ion Etching
Papež, Nikola
Study deals with the investigation of the surface after ion etching on two types of solar cells – based on widely available polycrystalline silicon and on durable gallium arsenide for use in more demanding environments. Solar cell morphology was compared using an electron microscope together with an Energy Dispersive X-ray detector to show distribution ratios of elements. Atomic force microscopy was used to accurately describe the heights and roughness structure. Raman spectroscopy to study of vibrational properties and the stress investigations.
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Charge transport in semiconducting radiation detectors
Pipek, Jindřich ; Belas, Eduard (advisor) ; Hazdra, Pavel (referee)
This thesis is focused on study of charge transport in semiconducting radiation detectors. Theoretical calculations of current waveforms based on continuity equation and drift-diffusion equation are done. Useful approximations of current waveforms for detector with shallow electron trap are discussed. Monte Carlo simulation of the current waveforms is proposed and applied to fit experimental current waveforms measured using laser-induced transient current technique and for evaluation of charge transport parameters of the detector such as electric field profile, trapping and detrapping time of traps, drift mobility and other parameters. Detectors prepared from semi-insulating GaAs and CdZnTe single crystals are tested using electrical, spectroscopic and optical characterization techniques.
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CREATION OF NANOSTRUCTURES ON SURFACES OF SOLID MATTER USING HYBRID METHODS
Rudolfová, Zdena ; Mikulík, Petr (referee) ; Horová, Ivana (referee) ; Kolíbal, Miroslav (advisor)
This thesis deals with the study of GaAs surface properties and with methodology of metal (mainly gold) nanoparticles deposition on GaAs substrate. GaAs has complicated surface oxides structure, which are very reactive when exposed to various chemicals (both acids and alkalines) and therefore they change GaAs surface properties. That is why the study of this properties is crucial for understanding of GaAs surface reactions on metal particles colloidal solution, from which the nanoparticles are deposited on the surface. The possibilites of GaAs surface etching and passivation are discussed. These should lead to surface stability enhancement during colloidal nanoparticles deposition. There was also studied the influence of adhesive polymer monolayer grown on GaAs substrate to the amount of nanoparticles deposited to the surface after substrate immersion into colloidal solution. This thesis concentrates on analyzing of methods, how the gold colloidal nanoparticles can be deposited selectivelly, only to defined areas. The areas were defined using charged particle beam.
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