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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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Design and Testing of methodology for in-situ sample cleaning for low voltage electron microscopy
Rudolfová, Zdena ; Vávra,, Ivo (referee) ; Kolíbal, Miroslav (advisor)
This thesis concentrates on the methodology of semiconductor samples preparation for low voltage scanning electron microscopy. In the first part a detailed theory of sample imaging using electron beam and difference between classical scanning electron microscopy (SEM) and low voltage scanning electron microscopy (LVSEM) is described. It is given a description of a contrast formation in SEM and LVSEM and theories describing a contrast formation of differently doped semiconductors. The second part contains experimental data. The advantages and disadvantages of cleavage and focused ion beam (FIB) milling as sample preparation techniques are discussed. FIB was found as the best method for sample preparation for the analysis of precisely defined location on the sample. It is necessary to use the lowest possible FIB accelerating voltage for final polishing, ideally 1 kV.
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Correction of phase image background in the digital holographic microscope using convolution
Rudolfová, Zdena ; Malina, Radomír (referee) ; Uhlířová, Hana (advisor)
This bachelor thesis concentrates on a correction of background in the phase image of cells from a transmitted-light digital holographic microscope (TDHM). Optical aberrations in the optical systems of the object and reference arms cause "deformation" of the phase image. The cell is not displayed on a background with a constant value of phase, it is displayed on a background with phase values continuously changing between different places in the image. A method for removing the consequence of this imperfection from the image is described in this thesis. The principle lies in partial convolution of the phase image with a convolution kernel determined by a two-dimensional Gaussian function with the same variance in the both axes. To eliminate loss of information about the cells, the convolution is computed only from those parts of the phase image which contain no cells. The result of the convolution is considered to be an approximation of the background. This approximation is then subtracted from the phase image. The resulting phase image has a constant background, containing only noise. The necessary mathematical concepts are resumed in the introductory part of the thesis. The basic principle of the TDHM image reconstruction is also described. As a part of the thesis, a computer programme Odečet pozadí (Background subtraction) was created, which processes the phase images from the TDHM using this method.
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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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Design and Testing of methodology for in-situ sample cleaning for low voltage electron microscopy
Rudolfová, Zdena ; Vávra,, Ivo (referee) ; Kolíbal, Miroslav (advisor)
This thesis concentrates on the methodology of semiconductor samples preparation for low voltage scanning electron microscopy. In the first part a detailed theory of sample imaging using electron beam and difference between classical scanning electron microscopy (SEM) and low voltage scanning electron microscopy (LVSEM) is described. It is given a description of a contrast formation in SEM and LVSEM and theories describing a contrast formation of differently doped semiconductors. The second part contains experimental data. The advantages and disadvantages of cleavage and focused ion beam (FIB) milling as sample preparation techniques are discussed. FIB was found as the best method for sample preparation for the analysis of precisely defined location on the sample. It is necessary to use the lowest possible FIB accelerating voltage for final polishing, ideally 1 kV.
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Correction of phase image background in the digital holographic microscope using convolution
Rudolfová, Zdena ; Malina, Radomír (referee) ; Uhlířová, Hana (advisor)
This bachelor thesis concentrates on a correction of background in the phase image of cells from a transmitted-light digital holographic microscope (TDHM). Optical aberrations in the optical systems of the object and reference arms cause "deformation" of the phase image. The cell is not displayed on a background with a constant value of phase, it is displayed on a background with phase values continuously changing between different places in the image. A method for removing the consequence of this imperfection from the image is described in this thesis. The principle lies in partial convolution of the phase image with a convolution kernel determined by a two-dimensional Gaussian function with the same variance in the both axes. To eliminate loss of information about the cells, the convolution is computed only from those parts of the phase image which contain no cells. The result of the convolution is considered to be an approximation of the background. This approximation is then subtracted from the phase image. The resulting phase image has a constant background, containing only noise. The necessary mathematical concepts are resumed in the introductory part of the thesis. The basic principle of the TDHM image reconstruction is also described. As a part of the thesis, a computer programme Odečet pozadí (Background subtraction) was created, which processes the phase images from the TDHM using this method.
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