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Selective growth of GaN on SiN
Hulva, Jan ; Kolíbal, Miroslav (referee) ; Mach, Jindřich (advisor)
This bachelor's thesis deals with the selective growth of gallium and gallium nitride on silicon nitride (SiN) substrates. Thin silicon nitride layers are deposited on silicon substrates. Oxide structures are prepared by the local anodic oxidation method (LAO) on SiN substrates. These surfaces can be editionally modified by etching in hydrofluoric acid. Modified substrates are used for the deposition of gallium or gallium nitride under ultra-high vacuum conditions. Consequently, ordering of deposited material was studied in areas modified by LAO. Chemical state of layers is studied by X-ray photoelectron spectroscopy. Morphology of surfaces is measured by the atomic force microscope (AFM).
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Preparation and analysis of nanostructures in UHV conditions
Gloss, Jonáš ; Spousta, Jiří (referee) ; Mach, Jindřich (advisor)
Cílem této bakalářské práce bylo skoumání přípravy a analýzy nanostruktur v podmínkách vysokého vakua (VV). Teoretická část klade důraz na gallium nitridové (GaN) nanostruktury. Ty pak byly analyzovány rastrovacím tunelovacím mikroskopem (RTM). Aby bylo možné analyzovat připravené vzorky ve VV RTM, bylo provedeno elektrochemické leptání wolfrámového drátu. Tato práce zhrnuje postup k vytvoření wolfrámových hrotů pro RTM. Kapitola o výrobě wolfrámových hrotů zahrnuje popis princípu elektrochemického leptání. Obrázky vyleptaných hrotů byly provedeny pomocí rastrovacího elektronového mikroskopu. Zaostřování hrotů pak bylo vykonáno fokusovaným iontovým svazkem. V této práci je také představena metoda pro opětovné ostření RTM hrotů elektronovým svazkem, vykonávaná in-situ. Bylo dokázáno, že je možné rutinně obdržet wolfrámové hroty s poloměrem křivosti rádovo v nanometrech.
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The photoluminescence properties measurement of ultrathin films
Metelka, Ondřej ; Mach, Jindřich (referee) ; Šamořil, Tomáš (advisor)
The thesis briefly describes the principles and types of luminescence. In the first following research of study is also discussed the equipment which is applicable to photoluminescence experiments, including the arrangement. The second research focuses on the influence of the properties of gallium nitride (GaN) (ultra) thin films and other structures prepared by various ways on shape of photoluminescence spectra. The paperwork also describes the further optimization of photoluminescent apparatus used for the measurement of photoluminescence spectrum in the UV light radiation which is located at the Institute of Physical Engineering at the Technical University. The extension of measurements at low temperatures (design and construction of its own cryostat) is added. The conclusion concernes the test measurements to determine the effect of various settings of the apparatus on the resulting measured photoluminescence spectrum.
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Reconstruction of ion gun and its application for deposition of thin films and nanostructures
Novák, Tomáš ; Mach, Jindřich (referee) ; Voborný, Stanislav (advisor)
This bachelor´s thesis deals with modification and experimental application of the ion device, generating and transporting nitrogen ion beam with energy in a range of 10-100 eV. Together with gallium effusion cell, this device can be used for deposition of gallium nitride (GaN) thin films. Nitrogen ion beam current significantly increased by shortening the optical part of the ion gun. A differential pumping provides the system with ultrahigh-vacuum conditions in the deposition chamber. Profiles of ion current density, appropriate for GaN depositions, were found by the optimization of potentials applied on electrodes of the ion gun. Due to increase of nitrogen-ion current, the depositon rate of the system raised from about tenth of nm/h to more than 10 nm/h. For experiments described in this paper, monocrystalline silicon (111) was used as a substrate. The effect of gallium and nitrogen ion fluxes on GaN growth was investigated, together with the effect of gold nanoparticles on a GaN growth. Thin films were analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Several specific morphologies of thin films were observed.
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Growth ultrathin of layers Au
Beránek, Jiří ; Kolíbal, Miroslav (referee) ; Mach, Jindřich (advisor)
The aim of this thesis is to study growth of ultrathin gold layers prepared by MBE (Molecular beam epitaxy) in UHV conditions. Differently modified sillicon served as a substrate and depositions were done at different temperatures of a substrate. Samples were analyzed by ToF LEIS for thickness, morfology was examined by SEM and AFM. X-ray photoelectron spectra were taken for chemical analysis. Gathered data together with their evaluation contribute to description and understanding of some processes during deposition and subsequent exposure of the sample to high temperatures. Experimental data and conslusions also prowide basis for further experiments and development of potential applications.
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Preparation of SiN ultrathin films
Dvořák, Martin ; Voborný, Stanislav (referee) ; Mach, Jindřich (advisor)
This bachelor´s thesis deals with design, testing and calibration of an effussion cell generating silicon atomic beam having thermal energy (0,1 - 1 eV). These beams are used for the preparation of Si and SiN ultrathin films. Silicon nitride and its applications in semiconductor industry are reviewed. First experiments with deposition of ultrathin films of Si and SiN are described. These layers have been analyzed by x-ray photoelectron spektroscopy (XPS) and atomic force microscopy (AFM).
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Development of the Atom and Ion Beam Sources
Tihlařík, Jan ; Voborný, Stanislav (referee) ; Mach, Jindřich (advisor)
This text is oriented for problems of creating ion beams. Thesis also describe the impact of ion optics to ion beam profile and preparing GaN layers. Also ion-atom source optimization and analysis of beam properties are there described. Also it was made deposition of GaN ultrathin layers on Si(111)dH at room temperature for different settings of atom-ion source electric electrodes.
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Upgrade of the device for depositions by ion beam sputtering
Páleníček, Michal ; Mach, Jindřich (referee) ; Bábor, Petr (advisor)
This thesis deals with concept and realization of device which allows loading without air intake. Vacuum technology and its theoretical bases are discussed as well. Moreover the thesis is based on description of the current deposition chamber and its principles. The main part deals with the description of the concepts of lock and load systems. The first concept that has not been realized is described just briefly. The second one is thorough with description of the individual solutions and methods. The work also contains simple instructions how to install the specimen. At the end are described some outputs of simulations that have been done to comprehend and solve any problems that might occur as specimen holder cooling and deflection of magnetic rod.
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Design and Construction of an Effusion Cell for Growth of Ultrathin Layers
Křápek, Ondřej ; Voborný, Stanislav (referee) ; Mach, Jindřich (advisor)
This Bachelor's work deals with the design, documentation and construction of effusion cell for deposition of ultrathin layers of various materials in conditions of ultrahigh vacuum. After fabrication and assemblage the effusion cell was placed to an ultrahigh vacuum chamber (p ~ 10-5 Pa) where the first testing deposition of a silver ultrathin film on Si (111) substrate was performed. This sample was studied by X-ray photoelectron spectroscopy and atomic force microscopy.
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