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Functional organic-inorganic nanostructures
Kelíšek, Petr ; Zmeškal, Oldřich (referee) ; Čech, Vladimír (advisor)
Diploma thesis deals with preparation of multilayered organic-inorganic nanostructures via PECVD technology and analysis of optical properties of these layers by spectroscopic ellipsometry. The theoretical part handles the definition of thin layers, layered and gradient nanostructures, plasma enhanced chemical vapor deposition and principles of spectroscopic ellipsometry. In the experimental part, used materials and chemicals are described, afterwards follow a complete description of the apparatus used for sample preparation and a description of the sample preparation procedure. The results part consists of methodology of preparing material models necessary for ellipsometric measurements and evaluation of optical properties of deposited nanolayers.
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Optical and magneto-optical properties of Heusler compounds
Král, Daniel ; Veis, Martin (advisor)
Cílem této práce bylo studium Heuslrových sloučenin pomocí optických a magneto-optických (MO) metod. V případě první sloučeniny, Co2FeGa0.5Ge0.5, jsme studovali výskyt strukturálního disorderu za pomoci spektroskopické elipsometrie, MO spektroskopie a MO Kerrovy magnetome- trie. Experimentální výsledky jsme poté porovnali s teoretickými modely. Doplnili jsme také výsledky našich spolupracovník·, a to včetně X-ray difrakce, atomic-force mikroskopie a ab initio výpočt·, abych potvrdili naši interpretaci naměřených výsledk·. Bylo zjištěno, že strukturální disorder je vskutku pozorovatelný pomocí metod, kterých jsme využili. Jeho výskyt se projevil změnou elektronové struktury vzork·. V případě druhé sloučeniny, Fe2MnGa, jsme vyšetřovali vliv obsahu Fe složky na optické a MO vlastnosti tohoto materiálu. Zjistili jsme, že atomy Fe ovlivňují koncentraci volných elektron·, čímž dodávají sloučenině kovový charakter (v porovnání s Ni2MnGa). Zároveň zvyšují optickou a MO odezvu v blízké infra-červené oblasti spektra. Dále bylo zjištěno, že vzorek s nejvyšším obsahem Fe má nulovou magnetizaci. 1
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Study of physical properties of Heusler alloys
Beran, Lukáš ; Veis, Martin (advisor)
This diploma thesis is devoted to systematic study of structural trans- formations of Heusler alloys by means of spectroscopic ellipsometry and magneto-optical spectroscopy. Structural transformations in these alloys are induced by different microscopic mechanisms. Obtained experimental results were confronted with theoretical calculations. This allowed the discussion of obtained results and suggestion of their interpretation. In the case of Co- Fe-Si alloys, changes in optical and magneto-optical properties with change of Co-Fe ratio were observer. This was explained by lowering of the gap for minority spins with increasing Fe concentrations. Temperature dependent optical and magneto-optical properties of Ni-Mn-Ga alloy showed the pres- ence of so-called Martensitic transformation from cubic to tetragonal phase. A study of Mn-Rh-Co-Sn alloys did not show a clear dependence of physical properties upon the concentration of Rh and Mn. This was explained by strong strain inside the samples, which distorted obtained results. 1
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Physics of interfaces in magnetic nano structures
Ohnoutek, Lukáš ; Veis, Martin (advisor) ; Urbánek, Michal (referee)
Modification of interfaces in nanostructures can significantly influence their overall properties. Magneto-optical spectroscopy and spectroscopic ellipsometry are ideal for studying these phenomena thanks to their in-depth sensitivity and contactless measurements. Two methods of nonreversible modification of magnetic properties, especially the magnetic anisotropy, are investigated. The measured spectral dependence of magneto-optical Kerr effect is compared to a theoretical calculation in order to determine the profile of the samples for different levels and methods of modification. In addition to this, ellipsometric measurements are performed on a device whose optical properties change by voltage application.
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Optical and magneto-optical properties of Heusler compounds
Král, Daniel ; Veis, Martin (advisor) ; Mistrík, Jan (referee)
Cílem této práce bylo studium Heuslrových sloučenin pomocí optických a magneto-optických (MO) metod. V případě první sloučeniny, Co2FeGa0.5Ge0.5, jsme studovali výskyt strukturálního disorderu za pomoci spektroskopické elipsometrie, MO spektroskopie a MO Kerrovy magnetome- trie. Experimentální výsledky jsme poté porovnali s teoretickými modely. Doplnili jsme také výsledky našich spolupracovník·, a to včetně X-ray difrakce, atomic-force mikroskopie a ab initio výpočt·, abych potvrdili naši interpretaci naměřených výsledk·. Bylo zjištěno, že strukturální disorder je vskutku pozorovatelný pomocí metod, kterých jsme využili. Jeho výskyt se projevil změnou elektronové struktury vzork·. V případě druhé sloučeniny, Fe2MnGa, jsme vyšetřovali vliv obsahu Fe složky na optické a MO vlastnosti tohoto materiálu. Zjistili jsme, že atomy Fe ovlivňují koncentraci volných elektron·, čímž dodávají sloučenině kovový charakter (v porovnání s Ni2MnGa). Zároveň zvyšují optickou a MO odezvu v blízké infra-červené oblasti spektra. Dále bylo zjištěno, že vzorek s nejvyšším obsahem Fe má nulovou magnetizaci. 1
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Studium fyzikálních vlastností Heuslerových slitin
Beran, Lukáš ; Veis, Martin (advisor) ; Mistrík, Jan (referee)
This diploma thesis is devoted to systematic study of structural trans- formations of Heusler alloys by means of spectroscopic ellipsometry and magneto-optical spectroscopy. Structural transformations in these alloys are induced by different microscopic mechanisms. Obtained experimental results were confronted with theoretical calculations. This allowed the discussion of obtained results and suggestion of their interpretation. In the case of Co- Fe-Si alloys, changes in optical and magneto-optical properties with change of Co-Fe ratio were observer. This was explained by lowering of the gap for minority spins with increasing Fe concentrations. Temperature dependent optical and magneto-optical properties of Ni-Mn-Ga alloy showed the pres- ence of so-called Martensitic transformation from cubic to tetragonal phase. A study of Mn-Rh-Co-Sn alloys did not show a clear dependence of physical properties upon the concentration of Rh and Mn. This was explained by strong strain inside the samples, which distorted obtained results. 1
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Study of optical properties of thin films of organic photovoltaic cells
Čuboň, Tomáš ; Schmiedová, Veronika (referee) ; Zmeškal, Oldřich (advisor)
This master´s thesis is focused on measurement of optical properties of thin layer of materials used in organic solar cells (OSC). The usage of graphene oxides and its reduced forms as parts of hole transport layer (HLT) in OSC were studied. At the beginning of the thesis, there is described basic theory necessary to understand the optical properties of thin layers. The thin layer deposition and reduction of GO are discussed too. The experimental part is aimed to the optical characterization of prepared thin films. The results from optical microscopy, UV-VIS spectroscopy, FT-IR spectroscopy and spectroscopic ellipsometry were obtained. At the end of the thesis, the results are concluded and compared with already published literature.
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Study of Optical Properties and Interference Phenomena on Thin Films of Organic Mcaterials
Schmiedová, Veronika ; Čeppan, Michal (referee) ; Mistrík, Jan (referee) ; Zmeškal, Oldřich (advisor)
Ph.D. thesis is focused on the study and determination of layer thickness and optical properties, such as the dispersion dependence of the refractive index of various materials prepared in the form of thin layer. In the first part of this work the theoretical findings in the field of spectroscopic ellipsometry are summarised. These findings are followed by the description and characterization of the light polarization, evaluation of experimental data and determination of the physical properties of studied materials. Experimental and result section of this work is devoted to the preparation and characterization of thin films of the studied materials: titanum dioxide (TiO2), new organic materials (MDMO-PPV, PCDTBT, PCBTDPP, PC60BM, PC70BM) and reduced graphene oxide (rGO). These were all selected with respect to their potential use in the organic photovoltaics.
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Ordered and disordered arrays of colloidal nanoparticles for biomolecule detection
Ligmajer, Filip ; Rezek, Bohuslav (referee) ; Kolíbal, Miroslav (advisor)
This thesis deals with guided self-assembly of gold nanoparticles from their colloidal solutions onto silicon substrates and possible employment of nanoparticles for detection of biomolecules. It was found that by adjustment of solution pH and surface chemistry modification by means of electron beam irradiation it is possible to facilitate nanoparticle deposition to patterns with almost single particle precision. Spectroscopic ellipsometry was then employed in analysis of self-assembled layers of nanoparticles and its combination with a theory of effective medium approximation has proven the ability to assess nanoparticle dimensions and volume fractions. By experiments with thiolated oligonucleotides it has been shown that using ellipsometry one can detect even with very subtle changes in nanoparticle environment caused by biomolecules, thus promising its possible use in the field of biodetection.
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