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Selective hydrogenation/Oxidation of CVD graphene using AFM
Přikryl, Vojtěch ; Švarc, Vojtěch (referee) ; Bartošík, Miroslav (advisor)
Graphene is a perspective material for utilization in electronics due to its high charge carrier mobility. However, in order to be applicable in practice the bandgap opening is necessary. One way of achieving this is modification of graphene by hydrogenation or oxidation. This work concerns the possibility of using AFM for local hydrogenation/oxidation of graphene depending on the bias voltage between the tip and the sample. The presence of hydrogenation/oxidation was examined by Kelvin probe force microscopy and Raman spectroscopy. The possibility of oxidation was proved but hydrogenation was not proved.
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Fabrication and application of graphene-metal heterostructure in biosensing by Surface Enhenced Raman Spectroscopy
Hegrová, Veronika ; Édes, Zoltán (referee) ; Konečný, Martin (advisor)
This thesis deals with fabrication of graphene/metal heterostructures and their application in biosensing by surface-enhanced Raman spectroscopy. The heterostructures are fabricated by selective deposition of gold colloidal nanoparticles onto silicon substrate, where the termination of both the gold colloidal solution and the silicon surface is controlled. Further, the assembled gold colloids are overlaid by graphene monolayer. The experiments have proved, that it is possible to observe the presence of biomolecules at very low concentrations if the parameters of graphene/metal heterostructures are well selected. The combination of both graphene and metal SERS properties have demonstrated their appropriateness for utilization in bisensing.
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Transport properties of single graphene domains
Vysocký, Filip ; Kormoš, Lukáš (referee) ; Procházka, Pavel (advisor)
This bachelor thesis is focused on the preparation of single graphene domains by chemical vapor deposition method, its transfer onto non-conductive substrates and subsequent fabrication of the grapehene field effect transistors. The theoretical part of the tesis deals predominantly with different procedures of graphene production. The practical part of the thesis describes the production of graphene field effect transistors by electron beam lithography and the measurement of their transport properties.
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Preparation of graphene nanostructures for applications
Dubnická Midlíková, Jana ; Procházka, Pavel (referee) ; Lišková, Zuzana (advisor)
The thesis deals with preparation of graphene nanostructures and their applications in the measurement of electrical transport properties of graphene. Graphene layers are prepared by mechanical exfoliation in two ways, by using adhesive tape or elastomeric film. The contacts for measurement of graphene layers resistance are fabricated by electron beam litography on exfoliated graphene flakes. Measurements of graphene transport properties take place in two environments, in air and in vacuum. Mobility and concentration of charge carriers of prepared graphene nanostructure are determined from the measured values.
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Selective hydrogenation of graphene prepared by chemical vapour deposition
Kovařík, Štěpán ; Nováček, Zdeněk (referee) ; Bartošík, Miroslav (advisor)
Controlled bandgap opening is one of the skills necessary for the application of graphene in electronics. The graphene hydrogenation is one of the possible ways to open the bandgap. In this work we deal with local hydrogenation of graphene prepared by chemical vapour deposition on a Si/SiO2 substrate. The hydrogenation was performed by atomic source of hydrogen and polymethyl methacrylate pattern was used for localization of hydrogenated structures on graphene. The pattern was prepared by electron beam lithography. The presence of structures formed by hydrogenated graphene was investigated by Raman spectroscopy, Kelvin probe force microscopy and PeakForce tunneling atomic force microscopy. All three methods have confirmed the local hydrogenation of graphene.
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Fabrication of graphene mid-infrared biosensor
Gallina, Pavel ; Hrabovsk, Milo (referee) ; Sadlek, Jakub (advisor)
The main subject of this bachelor's thesis was fabrication and measurement of response of graphene plasmonic biosensor prepared on flat and curved surfaces. Graphene produced by chemical vapour deposition (CVD) method was used for preparation of these sensors. The structures were fabricated using electron beam (EBL) and optical lithography, reactive ion etching (RIE) and magnetron sputtering. The resultant sensors were then observed in electron (SEM) and optical microscope, the topography was surveyed in atomic force microscope (AFM) and the measurement was carried out by Fourier transform infrared spectoscopy (FTIR).
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Design of the carbon atomic source for deposition of graphene in UHV
Čalkovský, Vojtěch ; Bábor, Petr (referee) ; Mach, Jindřich (advisor)
This bachelor's thesis deals with the design of the atomic carbon source for deposition of graphene layers in UHV conditions. In the first part are briefly described the problems of epitaxial growth, the theory of atomic beams and theory of sublimation. The second part is aimed on graphene description, namely on his properties and on the growth of graphene layers, especially by molecular beam epitaxy. The third part contains brief description of detection and analysis methods of carbon atomic beams. In the practical part of this bachelor's thesis the design and the numeric calculations were made in Simion 8.0 and EOD program. Afterwards the atomic carbon source was constructed. In the conclusion are discussed the obtained results.
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The hydrogen modification of the graphene structures for field effect transistors
Kurfürstová, Markéta ; Čermák,, Jan (referee) ; Mach, Jindřich (advisor)
This master’s thesis is focused on the subject of graphene modified with atomic hydrogen and its electronic transport properties. Structural and electronic properties of graphene and hydrogenated graphene are compared in the theoretical part of the thesis. The Raman spectroscopy technique is described, including characterization of typical Raman spectra of both unmodified and modified graphene. Samples used during experimental part of the thesis are prepared via laser and electron lithography, and are set to be measured in a vacuum chamber. Subsequently, electronic transport properties are measured before and after hydrogen modification of graphene. Finally, hydrogenated graphene is irradiated using electron beam and changes in its structure are analyzed with Raman spectroscopy techniques.
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The modification of the graphene structures by low energy ions (E
Maniš, Jaroslav ; Čermák,, Jan (referee) ; Mach, Jindřich (advisor)
Diploma thesis deals with the influence of low energy ions on graphene structures. Graphene structures were modified by nitrogen and argon ions of energies lower than 100 eV. Modified structures were analysed by Raman spectroscopy and x-ray photoelectron spectroscopy. The influence of the dose of ions on quality of graphene were investigated as well. In addition, this diploma thesis includes the literature search which focuses on modification of graphene by charged particles.
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