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Mechanical and Electrical Properties of Microcrystalline Silicon Thin Films
Vetushka, Aliaksei ; Fejfar, Antonín (advisor) ; Čech, Vladimír (referee) ; Sládek, Petr (referee)
Amorphous and nano- or micro- crystalline silicon thin films are intensively studied materials for photovoltaic applications. The films are used as intrinsic layer (absorber) in p-i-n solar cells. As opposed to crystalline silicon solar cells, the thin films contain about hundred times less silicon and can be deposited at much lower temperatures (typically around 200 0 C) which saves energy needed for production and makes it possible to use various low cost (even flexible) substrates. However, these films have a complex microstructure, which makes it difficult to measure and describe the electronic transport of the photogenerated carriers. Yet, the understanding of the structure and electronic properties of the material at nanoscale is essential on the way to improve the efficiency solar cells. One of the main aims of this work is the study of the structure and mechanical properties of the mixed phase silicon thin films of various thicknesses and structures. The key parameter of microcrystalline silicon is the crystallinity, i.e., the microcrys- talline volume fraction. It determines internal structure of the films which, in turn, decides about many other properties, including charge transport and mechanical sta- bility. Raman microspectroscopy is a fast and non-destructive method for probing the...
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Military Memorial Places in Czechia: Territorial Differences and Changes in Their Perception in the Context of Political Development
Sládek, Petr ; Havlíček, Tomáš (advisor) ; Kučera, Zdeněk (referee)
This diploma thesis deals with military memorial places and their spatial information. The work is processed within the new defined geographic direction Necrogeography and continues on discussion about taboo subject of death, cemeteries and military places. It is also a continuation of similar work on the theme of small religious monuments in Czechia. The work has several aims: It rates the role of military memorial places in the formation of regional and local identity. The other aim is to rate the territorial differentiation of military memorial places and how the form of military commemorative locations differs within Czechia. For the purpose of the work a typology of military memorial places was created which allows data to be compared and concluded. The aim of the research part of this diploma thesis is addition of spatial information of the current inventory of military commemorative places in Czechia and evaluation of territorial differentiation between the years 1918 - 1938 in model areas. Only the existing memorial places are taken to account because of inaccurate records of past memorial places in model areas (inability to capture every single military memorial place in the history of 20th century). Territorial differentiation of military places is analyzed through field research in model...
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Silicon solar cells: methods for experimental study and evaluation of material parameters in advanced structures
Holovský, Jakub ; Vaněček, Milan (advisor) ; Sládek, Petr (referee) ; Hlídek, Pavel (referee)
This work concerns with today's challenges of photoelectrical characterization methods in the research and development of thin film silicon solar cells. Relevant results are obtained only when photocurrent spectroscopy and measurement of current-voltage characteristics, are applied on the real structures that can however be multi-layered, multi-junction devices with nanostructured interfaces. Analytical and numerical optical models comprising light scattering are used for analysis of light absorption and for evaluation of optical absorption coefficient of silicon layers in sub-gap region. The slope of absorption edge and residual absorption in mid-gap indicate material disorder and defect density. Based on the investigation of electrical interaction between sub-cells in the dual-junction solar cell we developed new methods of evaluation of photocurrent spectra and current-voltage characteristics individually for each sub-cell with no need to contact them directly. Usability of Fourier Transform Photocurrent Spectroscopy as a robust method for photocurrent spectroscopy of amorphous silicon is thoroughly analyzed here. The issues of frequency dependence are addressed in detail and comparison with photothermal deflection spectroscopy is made.
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Silicon solar cells: methods for experimental study and evaluation of material parameters in advanced structures
Holovský, Jakub ; Vaněček, Milan (advisor) ; Sládek, Petr (referee) ; Hlídek, Pavel (referee)
This work concerns with today's challenges of photoelectrical characterization methods in the research and development of thin film silicon solar cells. Relevant results are obtained only when photocurrent spectroscopy and measurement of current-voltage characteristics, are applied on the real structures that can however be multi-layered, multi-junction devices with nanostructured interfaces. Analytical and numerical optical models comprising light scattering are used for analysis of light absorption and for evaluation of optical absorption coefficient of silicon layers in sub-gap region. The slope of absorption edge and residual absorption in mid-gap indicate material disorder and defect density. Based on the investigation of electrical interaction between sub-cells in the dual-junction solar cell we developed new methods of evaluation of photocurrent spectra and current-voltage characteristics individually for each sub-cell with no need to contact them directly. Usability of Fourier Transform Photocurrent Spectroscopy as a robust method for photocurrent spectroscopy of amorphous silicon is thoroughly analyzed here. The issues of frequency dependence are addressed in detail and comparison with photothermal deflection spectroscopy is made.
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Multimedia support of physics education
Koupil, Jan ; Dvořák, Leoš (advisor) ; Obdržálek, Jan (referee) ; Sládek, Petr (referee)
This thesis deals with possibilities of use of multimedia technology in physics education and describes a few new educational units. First chapter of the thesis contains a short definition of multimedia and a brief summary of the importance of multimedia in general. The main merits of the thesis are the four chapters regarding individual multimedia technologies. Firstly, the potentialities of utilization of video records in physics measurements are discussed, including a few new experiments. The second main topic is the slow motion video, its importance, use in physics lessons and the description of a series of recorded slow motion video clips. As the next point, the use of a computer sound card as a measurement tool in innovative experiments is discussed. Finally, in the last chapter a series of newly created computer programs for visualization of hydrogen atom orbital shapes is characterized. The created educational units have been tested and classroom experience, students' or teachers' feedback are presented in corresponding chapters.
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Military Memorial Places in Czechia: Territorial Differences and Changes in Their Perception in the Context of Political Development
Sládek, Petr ; Havlíček, Tomáš (advisor) ; Kučera, Zdeněk (referee)
This diploma thesis deals with military memorial places and their spatial information. The work is processed within the new defined geographic direction Necrogeography and continues on discussion about taboo subject of death, cemeteries and military places. It is also a continuation of similar work on the theme of small religious monuments in Czechia. The work has several aims: It rates the role of military memorial places in the formation of regional and local identity. The other aim is to rate the territorial differentiation of military memorial places and how the form of military commemorative locations differs within Czechia. For the purpose of the work a typology of military memorial places was created which allows data to be compared and concluded. The aim of the research part of this diploma thesis is addition of spatial information of the current inventory of military commemorative places in Czechia and evaluation of territorial differentiation between the years 1918 - 1938 in model areas. Only the existing memorial places are taken to account because of inaccurate records of past memorial places in model areas (inability to capture every single military memorial place in the history of 20th century). Territorial differentiation of military places is analyzed through field research in model...
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Mechanical and Electrical Properties of Microcrystalline Silicon Thin Films
Vetushka, Aliaksei ; Fejfar, Antonín (advisor) ; Čech, Vladimír (referee) ; Sládek, Petr (referee)
Amorphous and nano- or micro- crystalline silicon thin films are intensively studied materials for photovoltaic applications. The films are used as intrinsic layer (absorber) in p-i-n solar cells. As opposed to crystalline silicon solar cells, the thin films contain about hundred times less silicon and can be deposited at much lower temperatures (typically around 200 0 C) which saves energy needed for production and makes it possible to use various low cost (even flexible) substrates. However, these films have a complex microstructure, which makes it difficult to measure and describe the electronic transport of the photogenerated carriers. Yet, the understanding of the structure and electronic properties of the material at nanoscale is essential on the way to improve the efficiency solar cells. One of the main aims of this work is the study of the structure and mechanical properties of the mixed phase silicon thin films of various thicknesses and structures. The key parameter of microcrystalline silicon is the crystallinity, i.e., the microcrys- talline volume fraction. It determines internal structure of the films which, in turn, decides about many other properties, including charge transport and mechanical sta- bility. Raman microspectroscopy is a fast and non-destructive method for probing the...
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Web Interface for Network Anomaly Detection System
Sládek, Petr ; Kováčik, Michal (referee) ; Bartoš, Václav (advisor)
The goal of this work is to create a web interface for network anomaly detection system called HostStats. Its mission is to enable users to effectively work with data and statistics provided by the system. Web interface works as a plugin to NfSen as a completely independent web applications. Implementation took place in PHP using the Nette Framework, HTML5, CSS3, and JavaScript using the jQuery library.
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