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Fabrication and characterization of two-dimensional heterostructures
Majerová, Irena ; Švec, Martin (referee) ; Procházka, Pavel (advisor)
After the experimental discovery of graphene at the beginning of the 21st century, many other interesting 2D materials have been discovered. However, the electrical and optical properties of these layers are greatly influenced by the composition and quality of the surrounding materials. In order to preserve the exceptional properties of thin films, attention has gradually been drawn to heterostructures from 2D composite materials. This thesis describes the preparation and characterization of heterostructures composed of graphene and hexagonal boron nitride. In addition, a specific focus will be placed on optimizing the production process of heterostructures by the dry thin film transfer process, prepared by micromechanical exfoliation. Characterization and quality of prepared layers are controlled by Raman spectroscopy, while morphology is examined by atomic force microscope (AFM). Furthermore, the electrical properties of the graphene-hBN device are discussed and the charge carrier of the graphene field-effect transistor is measured.
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Preparation of 2D materials in an ultrahigh vacuum electron microscope
Dymáček, Michal ; Bartošík, Miroslav (referee) ; Kolíbal, Miroslav (advisor)
This thesis is devoted to preparation of multilayer graphene and h-BN by CVD method. In the theoretical part of this thesis, both materials are introduced, as well as the CVD method and SEM. In the experimental part, the equipment and samples are described, as well as the computer codes, that were made within this work and used for analysis of taken images, and experiments, that were carried out. Utilizing in-situ analysis in ultra-high vacuum scanning electron microscope, the goal was to answer a question how is the multilayer graphene formed on the surface. Also, the first experiments of preparation of h-BN in this aparature were carried out.
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Fabrication and characterisation of plasmonic antennas on selected thin film with aim to get enhanced absorption due to presence of strong coupling
Vodička, Martin ; Kepič, Peter (referee) ; Liška, Jiří (advisor)
Strong coupling systems offer many important applications in various fields such as photonics, chemistry, nonlinear optics and others. This Bachelor's thesis focuses on the fabrication of metal plasmonic structures suitable for the formation of strong coupling between localized surface plasmon antennas and hexagonal boron nitride (hBN) thin film phonons in the infrared region. In the case of inducing a strong coupling, an increase in absorption should occur, which makes it possible to use this system to fabricate an infrared detector, the so-called microbolometer. The thesis summarizes important findings from electromagnetic field theory, describes the formation of strong coupling from the perspective of classical physics and gives examples of systems with strong coupling. Furthermore, the formation of surface plasmon polaritons and localized surface plasmons (LSPs) is theoretically described. Plasmonic antennas, their fabrication, applications and physical properties of hBN are described. In the practical part of the thesis, fabrication of plasmonic antennas under or on hBN thin film has been realized. The fabricated samples were characterized by scanning electron microscopy and the spectral response was measured by Fourier transform infrared spectroscopy. In the spectra, the absorption of hBN at 7.3 m was confirmed and additional transmittance minima corresponding to the presence of antennas were detected. The presence of a strong coupling between the LSPs antennas and the phonons of the native SiO2 layer was probably observed. Whether there was a strong coupling between the LSPs antennas and the hBN phonons cannot be inferred from the the obtained results.
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Preparation of 2D materials in an ultrahigh vacuum electron microscope
Dymáček, Michal ; Bartošík, Miroslav (referee) ; Kolíbal, Miroslav (advisor)
This thesis is devoted to preparation of multilayer graphene and h-BN by CVD method. In the theoretical part of this thesis, both materials are introduced, as well as the CVD method and SEM. In the experimental part, the equipment and samples are described, as well as the computer codes, that were made within this work and used for analysis of taken images, and experiments, that were carried out. Utilizing in-situ analysis in ultra-high vacuum scanning electron microscope, the goal was to answer a question how is the multilayer graphene formed on the surface. Also, the first experiments of preparation of h-BN in this aparature were carried out.
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Fabrication and characterisation of plasmonic antennas on selected thin film with aim to get enhanced absorption due to presence of strong coupling
Vodička, Martin ; Kepič, Peter (referee) ; Liška, Jiří (advisor)
Strong coupling systems offer many important applications in various fields such as photonics, chemistry, nonlinear optics and others. This Bachelor's thesis focuses on the fabrication of metal plasmonic structures suitable for the formation of strong coupling between localized surface plasmon antennas and hexagonal boron nitride (hBN) thin film phonons in the infrared region. In the case of inducing a strong coupling, an increase in absorption should occur, which makes it possible to use this system to fabricate an infrared detector, the so-called microbolometer. The thesis summarizes important findings from electromagnetic field theory, describes the formation of strong coupling from the perspective of classical physics and gives examples of systems with strong coupling. Furthermore, the formation of surface plasmon polaritons and localized surface plasmons (LSPs) is theoretically described. Plasmonic antennas, their fabrication, applications and physical properties of hBN are described. In the practical part of the thesis, fabrication of plasmonic antennas under or on hBN thin film has been realized. The fabricated samples were characterized by scanning electron microscopy and the spectral response was measured by Fourier transform infrared spectroscopy. In the spectra, the absorption of hBN at 7.3 m was confirmed and additional transmittance minima corresponding to the presence of antennas were detected. The presence of a strong coupling between the LSPs antennas and the phonons of the native SiO2 layer was probably observed. Whether there was a strong coupling between the LSPs antennas and the hBN phonons cannot be inferred from the the obtained results.
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Fabrication and characterization of two-dimensional heterostructures
Majerová, Irena ; Švec, Martin (referee) ; Procházka, Pavel (advisor)
After the experimental discovery of graphene at the beginning of the 21st century, many other interesting 2D materials have been discovered. However, the electrical and optical properties of these layers are greatly influenced by the composition and quality of the surrounding materials. In order to preserve the exceptional properties of thin films, attention has gradually been drawn to heterostructures from 2D composite materials. This thesis describes the preparation and characterization of heterostructures composed of graphene and hexagonal boron nitride. In addition, a specific focus will be placed on optimizing the production process of heterostructures by the dry thin film transfer process, prepared by micromechanical exfoliation. Characterization and quality of prepared layers are controlled by Raman spectroscopy, while morphology is examined by atomic force microscope (AFM). Furthermore, the electrical properties of the graphene-hBN device are discussed and the charge carrier of the graphene field-effect transistor is measured.
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