National Repository of Grey Literature 22 records found  previous11 - 20next  jump to record: Search took 0.01 seconds. 
Low Energy Ions Scattering analysis of graphene layers prepared by CVD technology
Bábík, Pavel ; Kolíbal, Miroslav (referee) ; Průša, Stanislav (advisor)
This bachelor thesis is focused on the analysis of graphene samples by the Low Energy Ion Scattering (LEIS). The production of graphene layers is realized by the Chemical Vapor Deposition method (CVD) on the Institute of Physical Engineering. Analysis of the samples is taken place in the Central European Institute of Technology (CEITEC) by Qtac 100. The aim of this bachelor thesis is to optimize of technology in order to reduce contaminants in the graphene layer.
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.
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.
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.
Investigation of properties of CdTe single-crystals surfaces with sub-nanometer depth resolution
Čermák, Rastislav ; Bábor, Petr (referee) ; Šik, Ondřej (advisor)
V laboratořích Středoevropského technologického institutu – CEITEC je k dispozici unikátní zařízení Qtac, umožňující kvantitativně měřit složení horní atomové vrstvy různých materiálů včetně izolátorů. Qtac k tomu využívá nízkoenergiového rozptylu iontů, tzv. metodu LEIS. Kromě analýzy horní atomové vrstvy je LEIS v Dynamickém módu schopen určit hloubkový profil koncentrace prvku se sub-nanometrovým hloubkovým rozlišením.
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.
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.
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.
Comparative spectral analysis by ESA–LEIS and TOF–LEIS methods
Strapko, Tomáš ; Průša, Stanislav (referee) ; Bábor, Petr (advisor)
This bachelor thesis is about the overall procedure of the LEIS experiment with the aim to obtain reionization curve: from the construction adjustment of the original SARS set-up, through the construction assembly and electrical plug-in of the apparatus to the energy spectrum measurement of the pure copper sheet with following computation of reionization curve.
Low Energy Ions Scattering analysis of graphene layers prepared by CVD technology
Bábík, Pavel ; Kolíbal, Miroslav (referee) ; Průša, Stanislav (advisor)
This bachelor thesis is focused on the analysis of graphene samples by the Low Energy Ion Scattering (LEIS). The production of graphene layers is realized by the Chemical Vapor Deposition method (CVD) on the Institute of Physical Engineering. Analysis of the samples is taken place in the Central European Institute of Technology (CEITEC) by Qtac 100. The aim of this bachelor thesis is to optimize of technology in order to reduce contaminants in the graphene layer.

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