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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Modernizace aparatury IBAD / Improvement of IBAD apparatus

Urbánek, Ivan January 2008 (has links)
This thesis is divided into three main parts dealing with ion beam assisted deposition. In the first part there is a brief description of the IBAD chamber at Institute of Physical Engineering of BUT. There is also a detailed description of control of the IBAD apparatus during deposition. Next part deals with measuring of deposition rates of ion sputtering in order to refine deposition of thin layers. Last part deals with planned and already finished changes that should improve quality and speed of thin layers deposition. Changes include the option of covering the substrate holder, change of the entry flange, design of new insertion chamber with multifunctional substrate holder and the option to control the deposition by computer.
2

Automatizace a řízení depozice multivrstev metodou IBS/IBAD / Automation and control of multilayers deposition by IBS/IBAD

Pavera, Michal January 2011 (has links)
This diploma thesis deals with the automation of the deposition process by ion beam sputtering and ion beam assisted deposition. This work contains drawings of mechanical adjustments of the deposition chamber designed to control shutter and rotation of the target using stepper motors. There are presented ways to control stepper motors and troubleshoot their exact settings. Another task is to design a system for computer control of the deposition process. There are discussed ways to control the ion sources, pressure meter, flow meter and thickness meter, and their connection to a PC via RS-232 and analog-digital converters. It is also designed control program in LabVIEW, which allow automated multilayer deposition. Last part of the thesis deals with testing automatic deposition and results are commented.
3

Studium morfologie velmi tenkých vrstev XPS analýzou více spektrálních čar jednoho prvku / Morphology study of ultra thin layers by XPS analysis of multiple peaks of a single element

Pokorný, David January 2019 (has links)
This diploma thesis deals with methodology of thin film thickness determination using X-ray radiation of silver anode which provides radiation with energy of 2984,3 eV. This energy is twice as high as the standard aluminium radiation which allows a measurement of new photoelectron lines with higher bonding energy and it also provides thanks to the higher photoelectron energy greater information depth. In order to get the right results it was necessary to calibrate the spectrometer Kratos Axis Supra in the silver anode mode first and found out the form of the transmission function. The determination of the thickness of the thin layer was demonstrated by the comparation of the ratio of different photoelectron lines intensities with the theoretical model. For that purpose was specifically used the Si 1s and Si 2p peak bound in the substrate in the Si-Si bonding or in the thin oxid layer in the Si-O bonding. The results show that for thin SiO2/Si film thickness determination is the best to use the intensity ratio of only one photoelectron line. A silver anode however provides greater information depth.
4

Structure et propriétés optiques de nanoparticules couplées : application à la spectroscopie Raman exaltée de surface / Structure and optical properties of coupled nanoparticles : application to surface enhanced Raman spectroscopy

Yazidi, Senda 10 July 2018 (has links)
Ce travail vise à utiliser des surfaces d'alumine nanostructurées pour guider la croissance et l'organisation de particules métalliques (Ag, Au et AgxAu1-x), et à les tester en tant que substrats SERS-actifs robustes et réutilisables. Nous avons utilisé la spectrophotométrie pour la caractérisation des propriétés optiques résultantes, l'ellipsométrie spectroscopique pour l'extraction des indices optiques et la microscopie électronique en transmission pour les caractérisations structurales. La diffusion Raman exaltée de surface (SERS) a été utilisée pour la détection de molécules de bipyridine adsorbées sur la surface des échantillons, en collaboration avec l’Institut des Matériaux Jean Rouxel de Nantes. Nous étudions d'abord des systèmes de nanoparticules monométalliques et bimétalliques afin de comprendre les modes de croissance de telles assemblées. Nous montrons que des arrangements différents de nanoparticules bimétalliques sont obtenus selon la séquence de dépôt utilisée et qu'un alliage est obtenu à l'issue de recuits ex situ sous vide. Les propriétés optiques en champ proche et lointain de nanoparticules d'alliage AgxAu1-x noyées dans une matrice d'Al2O3 sont comparées numériquement à celles des métaux purs, par la méthode de calcul des différences finies dans le domaine temporel. Les résultats indiquent que l’amplification du champ pour les nanoparticules de métal pur est plus élevée que pour les nanoparticules d’alliage. Enfin, les expériences SERS menées sur un système dichroïque de nanoparticules d’Ag plus ou moins couplées montrent que l'on peut obtenir un signal SERS intense avec des nanoparticules recouvertes. / The aim of this work is to use nanostructured alumina surfaces to guide the growth and to optimize the organization of metallic particles (Ag, Au and AgxAu1-x), and to test those systems as reusable SERS-active substrates. We used spectrophotometry to characterize the resulting optical properties, spectroscopic ellipsometry for the determination of the optical index and transmission electron microscopy for the structural characterizations. Surfaced-enhanced Raman spectroscopy (SERS) was used for the detection of adsorbed bipyridine molecules on the sample surface, in collaboration with the Institut des Matériaux Jean Rouxel at Nantes. We first study systems consisting of monometallic and bimetallic nanoparticles in order to understand the growth modes of such particle assemblies. A particular attention is paid to the influence of the sequential deposition of Au and Ag on the structural and optical properties. We show that different arrangements of bimetallic nanoparticles are obtained according to the deposition sequence used and that an alloy is obtained after ex situ annealing under vacuum. The near-field and far-field optical properties of AgxAu1-x nanoparticle alloys embedded in an alumina matrix are compared numerically by the finite difference time domain method, with those of pure metal nanoparticles. Our results indicate that pure metal nanoparticles exhibit a greater field enhancement than alloy nanoparticles. Finally, SERS experiments conducted with a dichroic system made of coupled Ag nanoparticles show that an intense SERS signal can be obtained with coated nanoparticles.

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