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Deposition and optical properties of thin films and layered structures by PECVD
Kucharčík, Jan ; Boušek, Jaroslav (referee) ; Čech, Vladimír (advisor)
Thesis in theoretical part is focused on the principle of spectroscopic ellipsometry and formation of thin films by plasma-enhanced chemical vapor deposition (PECVD). In the experimental part we describe the deposition system, ellipsometer and mathematical evaluation of ellipsometric data, materials used for film formation and processing of the samples. Single-layer and multilayer structures of polymeric materials were prepared. We revealed that the optical properties of thin films are independent of film thickness. We also described the effect of the effective power and deposition gas mixture on optical properties of thin films.
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Adhesion of plasma polymer films deposited from tetravinylsilane monomer
Plichta, Tomáš ; Salyk, Ota (referee) ; Čech, Vladimír (advisor)
This bachelor thesis deals with the characterization of thin films of plasma polymers prepared from monomers of tetravinylsilane (TVS) and deposited on planar silicon substrates. Plasma enhanced chemical vapor deposition (PE CVD) was used as a method of thin films preparation. Three power series were prepared from pure TVS and two mixtures TVS with argon and oxygen. The main characterization methods were scratch tests and atomic force microscopy (AFM) is used to assess the adhesion degree of the layers and topography of scratches. To assess the characteristics and context the layer thickness was measured by spectroscopic ellipsometry (ELL) and elastic modulus using nanoindentation. The collected data were used to assess the reproducibility of the results with the regard to the purity of substrates and adhesion layers, depending on the deposition conditions and layers aging.
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Study of ferrimagnetic garnets thin films for photonic applications
Tázlarů, Stáňa ; Veis, Martin (advisor) ; Antoš, Roman (referee)
The aim of this thesis was an optical and magneto-optical characterization of thin layers of iron garnets prepared on silicon substrate by pulsed laser deposition method with emphasis on determining their suitability for use as materials for integrated optical isolators. The work is primarily dedicated to study of a single-layer terbium iron garnet samples and the influence of bismuth and cerium substitutions on their properties. Pre- sented values of a quality parameter, the figure of merit, are comparable with previously published results of two-layer structures of yttrium iron garnets and up to an order of magnitude higher than other available published values in this field. 1
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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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Synthesis of low-crosslinked polymers by plasma polymerization
Kuchtová, Štěpánka ; Bránecký, Martin (referee) ; Čech, Vladimír (advisor)
This bachelor thesis deals with plasma enhanced chemical vapour deposition (PECVD), specifically plasma polymerisation, which has been used for the synthesis of low density crosslinked polymer thin films. Organosilicon thin films were deposited on a silicon substrate by radio frequency (RF) capacitively coupled plasma in a deposition chamber. Spectroscopic ellipsometry was used to determine the layer thickness and its optical properties. The chemical structure of the layers was investigated by Fourier transform infrared spectroscopy and the mechanical properties were investigated by nanoindentation. The effect of power and self-bias (USB) on the chemical structure, mechanical and optical properties of the as-prepared layers, which are related to the crosslinking density, was investigated in the context of achieving low crosslinking density of the material. Low crosslinked plasma polymers were synthesized at a self-bias level of 1 V, which corresponds to an approximate RF power of 0,1 W. This material can be characterized by a density of 1, 2 g·cm-3 an elastic modulus of 4 GPa, a hardness of 0,04 GPa and a refractive index of 1.53 at 633 nm (He-Ne laser wavelength). Infrared spectroscopy confirmed that this plasma polymer is composed of a carbon network with fewer embedded silicon atoms and, in particular, the highest concentration of vinyl groups compared to plasma polymers prepared at higher powers.
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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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Study of ferrimagnetic garnets thin films for photonic applications
Tázlarů, Stáňa ; Veis, Martin (advisor) ; Antoš, Roman (referee)
The aim of this thesis was an optical and magneto-optical characterization of thin layers of iron garnets prepared on silicon substrate by pulsed laser deposition method with emphasis on determining their suitability for use as materials for integrated optical isolators. The work is primarily dedicated to study of a single-layer terbium iron garnet samples and the influence of bismuth and cerium substitutions on their properties. Pre- sented values of a quality parameter, the figure of merit, are comparable with previously published results of two-layer structures of yttrium iron garnets and up to an order of magnitude higher than other available published values in this field. 1
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