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The deposition of Ga and GaN nanostructures on silicon and graphene substrate
Novák, Jakub ; Jarý, Vítězslav (referee) ; Mach, Jindřich (advisor)
The thesis is focused on the study of properties of GaN nanocrystals and Ga structures on the surface of silicon and graphene substrate. In the theoretical part of this thesis, the basic properties of Ga/GaN and graphene are described, as well as their applications or connection of both structures together in different devices. The ability of metal nanoparticles to enhance not only photoluminescence, due to the interaction of the material with surface plasmons, is also shown in several examples. The experimental part of the work first deals with the production and characterization of graphene sheets prepared by Chemical Vapor Deposition. Ga/GaN growth on both types of substrates was performed in a UHV chamber using an effusion cell for Ga deposition and an atomic ion source for nitridation. Prepared structures were characterized using various methods (XPS, SEM, AFM, Raman spectroscopy or photoluminescence). In the last step, GaN nanocrystals were coated with Ga islands to study the photoluminescence enhancement.
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The deposition of Ga and GaN nanostructures on silicon and graphene substrate
Novák, Jakub ; Jarý, Vítězslav (referee) ; Mach, Jindřich (advisor)
The thesis is focused on the study of properties of GaN nanocrystals and Ga structures on the surface of silicon and graphene substrate. In the theoretical part of this thesis, the basic properties of Ga/GaN and graphene are described, as well as their applications or connection of both structures together in different devices. The ability of metal nanoparticles to enhance not only photoluminescence, due to the interaction of the material with surface plasmons, is also shown in several examples. The experimental part of the work first deals with the production and characterization of graphene sheets prepared by Chemical Vapor Deposition. Ga/GaN growth on both types of substrates was performed in a UHV chamber using an effusion cell for Ga deposition and an atomic ion source for nitridation. Prepared structures were characterized using various methods (XPS, SEM, AFM, Raman spectroscopy or photoluminescence). In the last step, GaN nanocrystals were coated with Ga islands to study the photoluminescence enhancement.
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Highly luminescent nanophosphors - new physics, technologies and applications
Nikl, Martin ; Čuba, V. ; Bárta, J. ; Jarý, Vítězslav
The application of radiation synthesis in the manufacturing nanopowders of binary and ternary oxide nanophosphors is reviewed. Technological routes are described: irradiation of specific solutions containing soluble metal salts and OH radical scavenger by UV or ionizing radiation results in the formation of finely dispersed solid phase which is separated from the solution and subsequently converted by further thermal treatment into crystalline nanopowders with typical dimension of grains of several tens of nanometers. Doped ZnO, Y2O3, Y3Al5O12, Lu3Al5O12 and Gd3(Ga,Al)5O12 nanophosphors were prepared and their luminescence and scintillation characteristics were measured. In the photoluminescence decay of doped garnets the distinct effect of nanosized grains was found consisting in the slowing-down of the decay due to the change of effective refractive index.
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