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Signal Detection by Segmental Ionization Detector in Environmental SEM
Černoch, Pavel ; Jirák, Josef (advisor)
The dissertation thesis deals with signal detection by an ionization detector in the environmental scanning electron microscope and utilization of this detector to gain required information in a specimen image. Main interest is focused on the detector containing several electrodes with a varied geometry arrangement and voltages on these electrodes. The detector was named segmental ionization detector. Detection capabilities of the segmental ionization detector were studied through computer simulations and experiments in the microscope utilizing knowledge from a technical literature background. On the base of the accomplished experiments, the segmental ionization detector has been optimized for the secondary electron detection improvement and at another configuration optimized for a high material contrast acquisition of the specimen image. Consideration of benefits of the examined segmental ionization detectors is included in the work.
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Scintillation SE detector for ESEM
Odehnal, Adam ; Špinka, Jiří (referee) ; Jirák, Josef (advisor)
Thesis deals with theoretical knowledge about scanning electron microscopy and environmental scanning electron microscopy. It describes principle of operation, signals generated by interaction between primary electron beam and specimen and means of detection of secondary electron signal in environmental conditions using scintillation detector. Furthermore, thesis focuses on optimization of detection od secondary electrons by adjusting electrode system of scintillation detector. Computer program Simion is used for modelling signal electron trajectories for proper adjustments. Simulation were starting-point for adjusting the design of the detector. Detection efficiency of adjusted detector was determined by evaluating signal magnitude from captured images, secondary electron detection capability from voltage contrast and quality of the captured images from signal/noise ratio.
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Contrast in image aquired by scintillation SE detector for VP SEM
Koudela, Oldřich ; Špinka, Jiří (referee) ; Jirák, Josef (advisor)
First part of this thesis is a theoretical essay which deals with the basics of scanning electron microscopy, with structure and function of a scanning electron microscope, its’ special case of an various pressure scanning electron microscope, electron interaction with surrounding environment and with a scintillation detector. The applied part of the thesis is focused on evaluation of material contrast on Cu-W specimen. Material contrast is evaluated for different pressures of water vapors in the microscope specimen chamber and for different detection conditions.
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Method of Voltage Contrast in ESEM
Buchta, Michal ; Černoch, Pavel (referee) ; Jirák, Josef (advisor)
This graduation thesis deals with the problem of voltage contrast in ESEM. The purpose of this work was to verify influence of used detectors in the dependence on conditions in specimen chamber on the size of voltage contrast. With the conditions in specimen chamber we understand pressure and working conditions of signal detection. We used power transistor as specimen.
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Observation of Insulators in ESEM
Matějka, Milan ; Špinka, Jiří (referee) ; Jirák, Josef (advisor)
This graduation theses in introduction deals with principle and problems of electron signal detection in scanning electron microscopy and charging of insulating specimens in SEM. The experimental part of the thesis describe the methods of qualification and quantification of insulating specimen charging effect observed in environmental scanning electron microscope through the use of ionisation and scintillation detector in dependence on water vapour pressure in specimen chamber. The goal of the thesis is formation of the methodics useful to evaluate charging effect at insulating specimens observing and on the basis of measuring, determine optimal conditions for insulating specimen observation with ionisation and scintillation detector.
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System level analysis of thermal properties of integrated circuits
Vaněk, Martin ; Jirák, Josef (referee) ; Frk, Martin (advisor)
Hlavním cílem této práce je shrnout základní poznatky o tématech spojených s teplem, se zaměřením na aplikace v elektrotechnice, a provést měření tepelného odporu pouzder integrovaných obvodů. První část je praktická a zabývá se teorií přenosu tepla, tepelnými vlastnostmi materiálů a metodologií JEDEC pro měření tepelných vlastností pouzder integrovaných obvodů. Druhá část se skládá ze sestrojení teplotní komory s přirozeným prouděním, návrhu testovacích desek plošných spojů a tepelných měření. Na závěr je shrnuta metodologie pro měření tepelného odporu čip-okolí spolu s uvedením praktických poznatků z předchozích měření. Tato práce může sloužit jako základ pro další vyhodnocování tepelných vlastností integrovaných obvodů a pro ověřování přesnosti tepelných simulací. Také může pomoci při vyhodnocování tepelné vodivosti desek plošných spojů.
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Ionization Detector for Variable Pressure SEM
Černoch, David ; Špinka, Jiří (referee) ; Jirák, Josef (advisor)
This graduation theises deal with influence of an additional grating possitioned berween the sample and the ionisation detektor of the environmental scannin elektron microscope on signal detection. Signal level is measured for changing pressure, at different voltages on the aditional grating, at different sample - additional electrode distance and at different sample - detektor distance. Influence of the additional grating is simulated for real working conditions on PC.
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An alternative JPEG coder/decoder
Jirák, Jakub ; Kiska, Tomáš (referee) ; Rajmic, Pavel (advisor)
The JPEG codec is currently the most widely used image format. This work deals with the design and implementation of an alternative JPEG codec using proximal algorithms in combination with the fixation of points from the original image to suppression of artifacts created in common JPEG coding. To solve the problem, the prox_TV and then the Douglas-Rachford algorithm were used, for which special functions using l_1-norm for image reconstruction were derived. The results of the proposed solution are very good because they can effectively suppress the artefacts created and the result corresponds to the image with a higher set qualitative factor. The proposed method achieves very good results for both simple images and photos, but in the case of large images (1024 × 1024 px) and larger, a large amount of computing time is required, so the method is more suitable for smaller images.
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Fundamental properties of semicomductor materilas
Kahánek, Tomáš ; Jirák, Josef (referee) ; Špinka, Jiří (advisor)
This work deals with fundamental properties of semiconductors materials and methods of their measuring. This work is focused on non-contact methods using light to generate electric charge in semiconductor. Tests were focused on measuring characteristics of PN transition light diods and semiconductor specimen with big resistivity, there was founded absorption edge of silicon.
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