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A method for reducing the complexity, and increasing the accuracy of field emission electron gun simulations
, Article Vacuum ; Volume 95 , 2013 , Pages 50-65 ; 0042207X (ISSN) ; Rashidian, B ; Sharif University of Technology
2013
Abstract
Problems regarding simulation of field emitter array (FEA) electron guns are discussed. A simple method is proposed to significantly reduce computational requirements such as computation power, system memory, and time of FEA electron gun simulation and modeling. The method can be applied to any numerical solver regardless of its meshing technique. In order to extract field emission parameter from any experimental cathode I-V curve, a partly numerical algorithm, which uses the presented truncation method at the heart of its solver, is proposed. The proposed method and algorithm are applied to a number of examples, including a double-gated FEA problem, and its effectiveness in terms of error...
Modeling and Improving the Thickness Distribution in Vacuum Coating System
, M.Sc. Thesis Sharif University of Technology ; Rashidian, Bizhan (Supervisor)
Abstract
In the fabrication of semiconductor devices, uniformity of thin films has many important influences on optical and electrical properties of the device. many attempts have been done on the enhancement of the uniformity of thin films so far. In this thesis, first the effect of angular variation of source with respect to the target on uniformity in the evaporation coating system has been studied, then an in situ positioning system for substrate has been designed and fabricated. After finding the thickness’s profile for Ag and Cu in Electron Beam Gun system, we studied the motion pattern of the target for improving the uniformity. This positioning system can be used to any coating systems. in...
Optimization of Nanostructures for Electron Emission
, Ph.D. Dissertation Sharif University of Technology ; Rashidian, Bizhan (Supervisor)
Abstract
The need for better characterization systems (electron microscopes) and high resolution lithography systems, have made electron beams systems an interesting choice for research and development. In fact, all of the above applications require ideal electron beams (beams with minimum energy spread, maximum current density, and minimum spotsize), and electron-optic lenses (simple lenses with minimum aberration). In this research, theoretical aspects of electron emission and lens systems are reviewed. Field emission array (FEA) electron guns are introduced as electron sources with minimum energy spread, and a new simulation method is presented in order to minimize the complexity, and reduce the...
Multifractal and optical bandgap characterization of Ta2O5 thin films deposited by electron gun method
, Article Optical and Quantum Electronics ; Volume 52, Issue 2 , 2020 ; Rezaee, S ; Mwema, F ; Luna, C ; Ghosh, K ; Jurečka, S ; Ţălu, Ş ; Arman, A ; Grayeli Korpi, A ; Sharif University of Technology
Springer
2020
Abstract
The micromorphology of tantalum pentoxide (Ta2O5) thin films, deposited on glass substrates by electron gun method, has been analyzed using atomic force microscopy (AFM), UV–Vis–NIR spectrophotometry and multifractal analyses. Two samples were grown at basic pressure of 7 × 10−6 mbar, work pressures of 1.3 × 10−4 and 2.0 × 10−4 mbar, and thicknesses of 0.38 μm and 0.39 μm, respectively. Subsequently, these samples were annealed at 300 °C for 2 h. The physical, structural and optical analyses were investigated by spectroscopic ellipsometry, spectrophotometry and AFM. The measured transmittance spectra were studied based on the Swanepoel method, whose results also yielded to the estimation of...
Research on the effect of transients of high-voltage power supplies on the lifetime of high-power vacuum tubes: A microscopic assessment
, Article IEEE Transactions on Plasma Science ; Volume 50, Issue 11 , 2022 , Pages 4700-4708 ; 00933813 (ISSN) ; Ziaoddini, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
Electron guns are used as the electron sources in high-power electron tubes. The generated electron beam in electric guns passes through an aperture at the center of the anode. Since the electron beam has considerable kinetic energy, any collision between the electron beam and the anode aperture edge damages the electron gun. Therefore, electron guns are designed to meet the compatibility between the diameters of the electron beam and the anode aperture. However, this compatibility is disrupted during the transient time interval of the gun's power supply. In this article, the cause of failure of the electron gun of high-power electron tubes is investigated for the transient interval of the...