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Analysis and modification of thin layers using ion beams
Jonner, Jakub ; Lörinčík, Jan (referee) ; Bábor, Petr (advisor)
This diploma thesis deals with analysis and modification of thin layers using ion beams. The first part of this diploma thesis deals with phenomena accompanying ion beam bombardment of solid matter. The second part of this diploma thesis is concerned with Secondary Ion Mass Spectroscopy (SIMS) and Low Energy Ion Scattering (LAIS). This work convey some basic information about these two techniques and it also deals with some benefits result in their connection into parallel depth profiling mode (such as better depth resolution of the LEIS profile, quantification of the SIMS). These benefits are demonstrated on MoSi film measurement. Within the framework of this thesis a new UHV manipulator was designed. This new UHV manipulator is equipped with precise stepper UHV motor and since the proportions are smaller, the manipulation with a sample in a space limited UHV chamber is much more comfortable and more precise. The third part of this diploma thesis deals with ion-beam induced transformation of epitaxially grown Fe films with thickness of 22 monolayer (ML) and 44 ML on Cu(100) single crystal at room temperature. Metastable Fe films of 22 ML thickness were prepared in CO pressure and 44 ML Fe films were prepared by co-evaporation of Fe with Fe64Ni36 (invar). Structural changes are analyzed by scanning tunneling microscopy and low-energy electron diffraction. The aim of this thesis is to discuss the influence of the sputtering parameters such as ion dose and ion energy on the nucleation of bcc nanocrystals, their growth, final shape and size. The influence of different Ni concentration on stability of 44 ML thick Fe films is also discussed.
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Depth profiling of multilayers by LEIS
Strapko, Tomáš ; Duda, Radek (referee) ; Bábor, Petr (advisor)
Diplomová práce se zabývá vytvořením modelu, který by umožnil lepší interpretaci hloubkových profilů měřených metodou LEIS. Obtížnost interpretace těchto profilů je dána vysokým podílem vícenásobně odražených projektilů v meřených spektrech. Tyto projektily nepřináší užitečnou informaci z dané hloubky. Naproti tomu jednonásobně odražené projektily nesou přesnější informaci o složení a tloušťce vrstev. V této práci vytvořený model se snaží určit příspěvek jednonásobně odražených částic k celkovému tvaru spektra a na základě něj i hloubkový profil vzorku.
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Upgrade of the UHV manipulator for SIMS and LEIS methods
Dao, Tomáš ; Polčák, Josef (referee) ; Bábor, Petr (advisor)
This bachelor’s thesis deals with the design and the construction of the manipulator, which operates under ultra high vacuum. In the first section, the original design and realization of the manipulator with six motion axis is introduced. Second section deals with the modifications of the manipulator. Advantages and disadvantages of the design are discussed and a new design of the manipulator, based on the experience from manipulator operation, is projected. Section is mainly focused on the design of the sample rotation using a stepper motor working in the ultra high vacuum. The new Faraday cup was also designed and tested. The last section contains the LEIS structural analysis measurement using the manipulator.
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Charge Exchange processes involved in projectile-target interaction at low energy range studied by HS-LEIS
Bábík, Pavel ; Král, Jaroslav (referee) ; Průša, Stanislav (advisor)
This diploma thesis is focused on the charge exchange processes between projectile and target studied by the Low Energy Ion Scattering (LEIS) technique. Basic premise to investigate charge exchange processes is correct cleaning processes and proper settings of experimental instrument Qtac 100 placed in the Central European Institute of Technology (CEITEC) in Brno. Ion fraction expresses neutralization rate of the projectile. The parametr is investigated for clean and oxidized polycrystalline copper. Oxygen presence performs a significant part of reionization of backscattered neutralized projectiles.
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Surface contamination of optical elements studied by Low Energy Ion Scattering LEIS
Sekula, Filip ; Kolíbal, Miroslav (referee) ; Průša, Stanislav (advisor)
This thesis focuses on study of surface contamination of optical elements using the low energy ion scattering method, LEIS. Presence of surface contaminations on optical elements has a negative contribution on thin layers that are applied upon them. The contamination can occur between the steps of manufacturing process. By determining the composition of the contaminations it could be possible to increase effectiveness during the growth of thin layers. Measurement is realised on right angle prisms at room temperature. We also focus on construction of sample holder that would allow heating of samples in the preparation chamber. Later we measure reference spectra for quantification of surface contamination.
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Interaction of the noble gas ions and gallium with surfaces and thin layers studied by Low Energy Ion Scattering LEIS
Chmelický, Martin ; Caha, Ondřej (referee) ; Průša, Stanislav (advisor)
In this thesis we study the interaction of helium, neon, argon and gallium ions with graphene. The graphene structure is contaminated with gallium ions during the graphene processing by focused gallium beam (FIB). The graphene properties are affected, e.g. reducing the electrical conductivity. The aim of this thesis is to verify the effect of selected ion beams on the graphene structure and select suitable ion beam for sputtering. Furthermore, the modification of standard heating stage used in LEIS instrument (Qtac 100) was designed and implemented. The LEIS instrument is connected to the complex UHV system for deposition and analysis of nanostructures – SPECS. This modification allows analysis of selected nanoparticles on suitable substrate at the elevated temperature.
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Quantitative analysis of matrix elements using SIMS and LEIS methods
Staněk, Jan ; Šik, Ondřej (referee) ; Bábor, Petr (advisor)
This thesis studies comparison and connection of two spectrometric methods – low energy ion scattering spektrometry (LEIS) and secondary ion mass spectrometry (SIMS). SIMS method, despite its many positive qualities, suffers of so called matrix effect, which makes quantifiaction of data very difficult. LEIS method on the other hand is immune to this effect and so it’s suitable completion of SIMS method. As a convenient sample have been chosen AlGaN samples with various concentration of gallium and aluminium. In the first part of thesis is introduced physical essence of SIMS and LEIS method, experimental details and studied samples. In second part of the thesis there’s a description of measurements and comparison of data gained by each method.
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Environment-Dependent Surface Structure of Fe2O3(012)
Komora, Mojmír ; Dubroka, Adam (referee) ; Čechal, Jan (advisor)
Táto diplomová práca sa zaoberá štúdiom alfa-Fe2O3(012) vystaveného vodnému prostrediu. Súčasný stav poznania ohľadom oxidov železa s pozornosťou vkladanou do popisu alfa-Fe2O3 a jeho (012) povrchu je stručne zhrnutá. Experimentálná časť tejto práce začína s popisom unikátného zariadenia na depozíciu kvapalnej vody na povrchy monokryštalických vzoriek compatibilného s podmienkami ultra vysokého vákuua. Jednotlivé konštrukčné časti a detaily sú diskutované. Navrhnutý systém bol testovaný na vzorkách striebornej fólie a monokryštálu Fe3O4 s povrchovom v rovine [100]. Chemické zloženie a morfológia povrchu po experimente s kvapalnou vodou je diskutovaná. Navrhnuté zariadenie bolo použité na štúdium interakcie vody so známymi (1x1) a (2x1) povrchovými alfa-Fe2O3(012). Experimentálne dáta ukazujú, že voda sa viaže na obe reconštrukcie disociatívne s určitým množstvom molekulárnej vody naviazanej na adsorbované hydroxydi. (1x1) sa zdá javý stabilná po expozícii rôznym tlakom vodnej pary, zatial čo (2x1) vykazuje zmenu na (1x1) pri expozíciach vyšším tlakom vodnej pary alebo po niekolo minútovej expozíci electrónovému zväzku. Ďalej sú v tejto práci prezentované prvé výsledky z štúdie prechodu (1x1) rekonštrukcie na (2x1) pomocou mikroskpie nízkoenergiových elektrónov. Výsledky ukazujú, že táto premena na nižších teplotách je inciovaná na hranách atomárnych vrstiev a defektov na povrchu, ktorá potom postupuje smerom k stredu atomárnych terás. Meranie na vyšších teplotách vykazuje postupnú premenu povrchu naznačúju viaceru nukleačných centrech z ktorých sa (2x1) povrch širi ďalej.
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