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Contamination in semiconductor fabrication
Fojtášková, Helena ; Salyk, Ota (referee) ; Čech, Vladimír (advisor)
This bachelor thesis deals with contamination in the production of semiconductor substrates. It focuses on the efficiency and optimization of wet cleaning processes for monocrystalline silicon and silicon carbide semiconductor wafers. The thesis includes a literature research in the field of semiconductor manufacturing, wafer contamination and wafer cleaning processes. The most commonly studied metal contaminants include iron, copper and nickel, due to their high diffusivity, and therefore these elements were chosen for the experimental part. In the experimental part, wafers were prepared by targeted contamination to verify the effectiveness of the cleaning processes. Contamination analysis was performed using the vapour phase decomposition method combined with inductively coupled plasma mass spectrometry (VPD-ICP-MS) for silicon wafers and total reflection X-ray fluorescence (TXRF) for silicon carbide wafers. Based on the measurement results, the efficiency of the washing processes was evaluated and a procedure for process optimization was recommended.
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Microfluidic systems in silicon technology
Juránek, Dominik ; Fecko, Peter (referee) ; Gablech, Imrich (advisor)
This thesis is devoted to the topic of microfluidics and the functionality of microfluidic devices when working with blood. It further focuses on the use of microfluidic devices to cut blood cells. The first part of this work is dedicated to the theoretical background of microfluidics, it briefly introduces the history of microfluidic devices and the materials used for their integration, moreover, it talks about the methods used when constructing a microfluidic device in a silicon substrate. Lastly, this section includes a description of blood and its composition and some properties important for working with microfluidic devices. The practical part is concerned with the (manufacturing procedure of) creating a microfluidic and testing of device that can cut red blood cells.
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The power of solar radiation falling on a photovoltaic module
Kaliyev, Alexey ; Jandová, Kristýna (referee) ; Křivík, Petr (advisor)
The work is focused on the problem of the solar radiation power impacting on a photovoltaic module. In the theoretical part, the possibilities of using solar energy in renewable energy sources, especially in photovoltaic panels and solar collectors, were discussed and presented. Then the materials on the use of solar energy in these sources were reviewed. In addition, the three main components of incident solar radiation on a photovoltaic module or solar collector were described. Finally, the method for calculating the position of the sun across the sky was discussed and presented, as well as the method for calculating the various components of incident solar radiation on a photovoltaic module.
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Optical properties of silicon nanostructures for photovoltaics
Salava, Jan ; Trojánek, František (advisor) ; Žídek, Karel (referee)
Název práce: Optické vlastnosti křemíkových nanostruktur pro fotovoltaiku Autor: Bc. Jan Salava Katedra: Katedra chemické fyziky a optiky Vedoucí diplomové práce: doc. RNDr. František Trojánek, Ph.D., katedra chemické fyziky a optiky Abstrakt: V předložené práci jsou studovány křemíkové nanokrystaly umístěné v SiC matrici - jednotlivé vzorky se odlišují přidáním dopantu (boru) do příslušné vrstvy struktury během depozice metodou PECVD a pasivací vodíkem. Křemíkové nanokrystaly jsou významné zejména tím, že oproti své objemové verzi vykazují účinnou fotoluminiscenci a absorpci ve viditelné oblasti spektra. Změnami parametr· při přípravě lze ladit jejich vlastnosti s ohledem na konkrétní aplikaci. Základní myšlenka integrace křemíkových nanostruktur do solárních článk· spočívá ve zvýšení účinnosti konverze slunečního spektra kombinací několika tenkých vrstev s nanokrystaly a objemového Si článku tak, aby každá vrstva sluneční cely absorbo- vala určitou část spektra. Procesy, které se v těchto strukturách dějí krátce po excitaci nosič· náboje, však stále nejsou zcela popsány. Cílem práce je charakterizace těchto jev· metodami ča- sově rozlišené spektroskopie. Dalším úkolem je popsat vliv dopování jednotlivých částí materiálu a jeho pasivace ve vodíkové atmosféře na chování fotoexcitovaných nosič· a intenzitu...
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The significance of silica structures in chromist microorganisms.
Nováková, Dora ; Škaloud, Pavel (advisor) ; Němcová, Yvonne (referee)
The silica is one of the most common elements in the Earth's crust. During erosion it is released in soluble form to the environment, where some organisms can accumulate the silica and incorporate it to their bodies by biosilicification process. The organsims possessing this ability are widespread either when considering their position in eukaryotic tree of life, or their abundance in natural ecosystems. As a result, the whole global biogeochemical cycle of silica is controlled by biosilicificated organisms. In Chromista microorganisms, the silica is loaded to so-called "silica deposition vesicles" - membrane surrounded compartments, in which the silica is polymerated and formed into the final shape of silica structures during an ingeniously controlled in vivo process. Apparent differences in the process of silica deposition among Chromista microorganisms imply that this ability has developed independenty and repeatedly within the group. The most common silica structures are scales, bristles, cases, skeletons and cysts. The analogical structures often originated independently in unrelated lines of Chromista by means of convergent evolution. On the contrary, in some lineages of Chromista, the ability of biosilicification was suppressed. It is therefore very likely that the silica structures should...
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Study of optical nonlinearities in semiconductors and semiconductor nanostructures
Chlouba, Tomáš ; Trojánek, František (advisor) ; Filip, Radim (referee) ; Herynková, Kateřina (referee)
In the main part of this thesis I study the relaxation mechanisms of charge carriers in silicon nanocrystals in SiO2 matrix. One of the potential applications of these structures lies in photovoltaics, specifically in construction of all-silicon tandem solar cells. I studied the dynamics of carriers in these structures by methods of ultrafast spectroscopy which helped to unravel the microscopic behaviour of carriers, their transport, localization etc. Furthermore I investigated the doping of such structures as the technology of doping is crucial for manufacture of pn- junctions which are the core component of solar cells. At the end I delve into the dissipative Jaynes-Cummings model by mathematical modeling and theoretical calculations which describes among others microlasers and as such comes under a field of cavity quantum electrodynamics.
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Influence of Si surface passivation on growth and ordering of nanostructures
Matvija, Peter ; Kocán, Pavel (advisor) ; Rezek, Bohuslav (referee) ; de la Torre, Bruno (referee)
Silicon is currently the most widely used semiconductor material with applications ranging from solar cells and sensors to electronic devices. Surface functionalization of silicon with molecular monolayers can be used to tune properties of the material toward a desired application. However, site-specific adsorption of molecules or molecular patterning on silicon surfaces is a difficult task due to the high reactivity of silicon. In this work, we use scanning tunneling microscopy, ab-initio calculations and kinetic Monte Carlo simulations to study adsorption of organic molecules on a bare and thallium-passivated Si(111) surface. We show that the polarity of molecules has a large impact on bonding of the molecules with the bare surface. We demonstrate that, in comparison with the bare surface, molecules or single-atom adsorbates deposited on the Tl-passivated surface have significantly higher mobility. The increased mobility induces formation of 2D gases on the surface and enables formation of self-assembled molecular structures. We propose a novel method to directly visualize the 2D surface gases and we show that a phase of surface gases containing molecule-bound dipoles can be controlled by a non-homogeneous electric field. 1
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Evolution of silica structures in SAR protists
Čížková, Natálie ; Čertnerová, Dora (advisor) ; Kulichová, Jana (referee)
Silicon is an important element in the earth's crust. In nature it mainly occurs in the form of silicic acid. This element is used by marine and freshwater organisms to form their siliceous structures. The organisms that make up these structures are located throughout the phylogenetic tree and are not limited just to protist groups. The SAR line includes Stramenopila, Alveolata and Rhizaria. The main protist taxa forming the mentioned siliceous structures are in these groups. These are mainly diatoms, silicoflagellates, radiolarians and the group chrysophyceae. The formation of siliceous structures usually provides evolutionary benefits to organisms, such as protection of the cell from actions of biotic and abiotic factors. The availability of dissolved silicon changed during evolution, thus affecting the appearance and functionality of the structures of individual species. Structural changes were manifested by thinning of the shells, change of cell size, enlargement or decrease of pores, increase of the number of thorns or, conversely, their loss. The individual lines thus had to choose the best possible strategies in response to the decreasing availability of silicic acid. Therefore, there was frequent competition between the groups for the remaining dissolved silicon. The current diversity of...
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Design of a photovoltaic power plant for a family house near Jihlava
Dvořák, Vít ; Maule, Petr (referee) ; Vaněk, Jiří (advisor)
This diploma thesis deals with the design of a photovoltaic solar power station for a specific family house in the Jihlava region. The aim of the work was to get acquainted with technologies about the production of solar systems, evaluate the market in the Czech Republic and create a design of photovoltaic solar power station. Three designs of power stations were created with the help of the PV * SOL design system. Each design uses different photovoltaic cell technology. The result of each power station design is a complete finished project, which is based on many factors such as the efficiency of the entire system in a certain location, financial analysis, return on investment and more. In addition, these projects meet the conditions for the preparation of the subsidy program Nová zelená úsporám. At the end of the work, all three designed power stations are evaluated and with the help of multicriteria analysis, the best and most advantageous power station design for the given locality is determined. In the end, the idea of further development of the project is presented.
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Optical properties of silicon nanostructures for photovoltaics
Salava, Jan
Title: Optical properties of silicon nanostructures for photovoltaics Author: Bc. Jan Salava Department: Department of Chemical Physics and Optics Supervisor: doc. RNDr. František Trojánek, Ph.D., Department of Chemical Physics and Optics Abstract: In the presented work silicon nanocrystals located in the SiC matrix are stu- died - samples dier in adding a dopant (boron) into the particular layer of structure during deposition by PECVD and in hydrogen passivation. Silicon nanocrystals are very important because of their eective photolumine- scence and absorption in visible part of the spectrum, which is not observed in bulk silicon. Properties of such structures are tunable by changing parameters during preparation with respect to the nal application. The basic idea of nanostructures integration in silicon solar cells is to increase the conversion eciency of the solar spectrum combining several thin layers of nanocrystals and bulk Si cell so that each layer of solar cell absorbs a certain part of the spectrum. The processes that take place in these structures immediately after excitation of carriers, however, are still not fully described. The goal of this work is to characterize these phenomena using methods of time-resolved spectroscopy. Another object is to describe the inuence of doping of the...
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