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Phyllotactic Model Linking Nano and Macro World
Horáček, Miroslav ; Meluzín, Petr ; Krátký, Stanislav ; Urbánek, Michal ; Bok, Jan ; Kolařík, Vladimír
Recently, the arrangement of diffraction primitives according to a phyllotactic model was presented. This arrangement was used to benchmarking purposes of the e-beam writer nano patterning. The phyllotactic arrangement has several interesting properties. One of them is related with the coherence between the nanoor microscopic domain of individual optical primitives and the properties of visually perceived images crated by these structures in the macro domain. This paper presents theoretical analysis of the phyllotactic arrangement in the referred context. Different approaches enabling the creation of diffractive optically variable images are proposed. The practical part of the presented work deals with the nano patterning of such structures using two different types of the e-beam pattern generators. One of them is a system with a variable shaped beam of electrons, while the other one is a system with a Gaussian-shaped beam. E-beam writing strategies and the use of inherent spiral patterns for exposure ordering and partitioning are also discussed.
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Gas Microsensors Based on Self-Organized 3D Metal-Oxide Nanofilms
Pytlíček, Zdeněk ; Husák, Miroslav (referee) ; Kolařík, Vladimír (referee) ; Prášek, Jan (advisor)
This dissertation concerns the development, fabrication and integration in a gas sensing microdevice of a novel 3-dimensional (3D) nanostructured metal-oxide semiconducting film that effectively merges the benefits of inorganic nanomaterials with the simplicity offered by non-lithographic electrochemistry-based preparation techniques. The film is synthesized via the porous-anodic-alumina-assisted anodizing of an Al/Nb metal bilayer sputter-deposited on a SiO2/Si substrate and is basically composed of a 200 nm thick NbO2 layer holding an array of upright-standing spatially separated Nb2O5 nanocolumns, being 50 nm wide, up to 900 nm long and of 8109 cm2 population density. The nanocolumns work as semiconducting nano-channels, whose resistivity is greatly impacted by the surface and interface reactions. Either Pt or Au patterned electrodes are prepared on the top of the nanocolumn array using an innovative sensor design realized by means of microfabrication technology or via a direct original point electrodeposition technique, followed by selective dissolution of the alumina overlayer. For gas-sensing tests the film is mounted on a standard TO-8 package using the wire-bonding technique. Electrical characterization of the 3D niobium-oxide nanofilm reveals asymmetric electron transport properties due to a Schottky barrier that forms at the Au/Nb2O5 or Pt/Nb2O5 interface. Effects of the active film morphology, structure and composition on the electrical and gas-sensing performance focusing on sensitivity, selectivity, detection limits and response/recovery rates are explored in experimental detection of hydrogen gas and ammonia. The fast and intensive response to H2 confirms the potential of the 3D niobium-oxide nanofilm as highly appropriate active layer for sensing application. A computer-aided microfluidics simulation of gas diffusion in the 3D nanofilm predicts a possibility to substantially improve the gas-sensing performance through the formation of a perforated top electrode, optimizing the film morphology, altering the crystal structure and by introducing certain innovations in the electrode design. Preliminary experiments show that a 3D nanofilm synthesized from an alternative Al/W metal bilayer is another promising candidate for advanced sensor applications. The techniques and materials employed in this work are advantageous for developing technically simple, cost-effective and environmentally friendly solutions for practical micro- and nanodevices, where the well-defined nano-channels for charge carriers and surface reactions may bring unprecedented benefits.
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SMV-2016-03: Precise relief structures
Matějka, Milan ; Horáček, Miroslav ; Meluzín, Petr ; Chlumská, Jana ; Král, Stanislav ; Kolařík, Vladimír ; Krátký, Stanislav ; Fořt, Tomáš ; Oulehla, Jindřich ; Šerý, Mojmír
Research and development in the field of precise relief structures using electron beam lithography and other ultra-precise micro manufacturing techniques.
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Laser and Phyllotaxy
Kolařík, Vladimír ; Horáček, Miroslav ; Krátký, Stanislav ; Meluzín, Petr ; Chlumská, Jana ; Matějka, Milan ; Král, Stanislav
The paper presents planar diffractive structures with optical elements arranged in positions according to a phyllotactic model. Further, we discuss the creation of a diffractive phyllotactic pattern and its properties. One of the particular arrangements, a nesting of two different phyllotactic models possessing a different level of fineness, is described in details. The discussed arrangement of elements within a circle can be used also in the laser beam splitting application.
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Submicron Structures with Deep Relief — Technology of Preparation
Matějka, Milan ; Kuřitka,, Ivo (referee) ; Mgr. Petr Klapetek Ph.D (referee) ; Kolařík, Vladimír (advisor)
The dissertation thesis is focused on research and development in the field of microfabrication by the technology of electron beam lithography. In the first part of this work, the extensive study is conducted in the field of technology of electron beam lithography in terms of physical principles, writing strategies and resist materials. This is followed with description of physical principles of etching for the transfer of relief structures into substrates. The thesis describes innovative techniques in modelling, simulation, data preparation and optimization of manufacturing technology. It brings new possibilities to record deep binary or multilevel microstructures using electron beam lithography, plasma and reactive ion etching technology. Experience and knowledge in the large area of microlithography, plasma and anisotropic wet-etching of silicon have been capitalized to the design process of manufacturing of nano-patterned membranes. It was followed with practical verification and optimization of the microfabrication process.
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Large-area gray-scale structures in e-beam writer versus area current homogeneity and deflection uniformity
Kolařík, Vladimír ; Horáček, Miroslav ; Matějka, Milan ; Krátký, Stanislav ; Bok, Jan
The high stability and good current homogeneity in the spot of the e-beam writer is crucial to the exposure quality, particularly in the case of large-area structures when gray-scale lithography is used. Even though the deflection field distortion is calibrated regularly and beam focus and beam astigmatism is dynamically corrected over the entire deflection field,\nwe can observe disturbances in the exposed relief for both nowadays types of e-beam writers, the shaped e-beam writing system and the Gaussian e-beam writing system. A stable and homogeneous angular current density distribution in the spot is important especially in the case of shaped e-beam lithography systems. A non-homogeneity of the spot over deflection field is seen alongside the field boundaries of both lithography systems.
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Mechanical and Electrical Properties of Thin Metal Films Deposited by Vacuum Evaporation
W. F. Yahya, Doaa ; Kolařík, Vladimír (referee) ; Štencl,, Jiří (referee) ; Šandera, Josef (advisor)
Thin layers are widely used in many fields of technology and today we can say that they are found in all modern technologies. Thin layers can be created in two ways, namely by chemical or physical means. This work focuses on the latter method, more particularly a technology of thermal evaporation of thin layers in a vacuum. The work focuses on the process principles during and after the evaporation. Much of the work focuses on the development and design of experiments. These experiments illustrate some of the phenomena that take place on thin films produced by the aforementioned technology. Work helps to better understand processes during formation of thin layers and properties that influence the quality and stability of thin films. In conclusion we describe results of experiments and new developments in the field of thin films deposition using evaporation under vakuum are summarized.
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Electron Beam Control and Diagnostics for Advanced Technologies
Zobač, Martin ; Kolařík, Vladimír (referee) ; Průša, Stanislav (referee) ; Lencová, Bohumila (advisor)
The thesis deals with problems of control and diagnostics of electron beam technological devices which use electron beam for localised intensive heating of a material. A brief description of the electron beam welder MEBW-60/2 is included; the author has participated on its development and implementation. Main topics are the analysis of deflection system properties and the measurement of current distribution of the beam (so-called beam profiles). Geometrical aberrations, hysteresis, stability and dynamics of a single-stage magnetic x-y deflection system are described. Suitable measurement procedures and correction methods are introduced. Methods of transverse and longitudinal beam profile acquisition is presented using successive sampling of the local current density of the beam by a modified Faraday cup. The data processing and evaluation of characteristic beam parameters are shown. The presented methods were verified by fourteen experiments using the electron beam welder. The methods have proven to be useful in practical evaluation of the device properties.
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