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Voltage contrast method in ESEM
Krňávek, Martin ; Čudek, Pavel (referee) ; Jirák, Josef (advisor)
This work contains theoretical description of basic features and principles of electron microscopy, with focus on environmental scanning electron microscopy. It describes function of the microscope, interactions that takes place after collision of electron pack with a sample, mainly it describes creation of back reflected electrons and secondary electrons and methods of voltage contrast. The practical part focus on voltage contrast issue by observing decomposition of electric potentials on surface of semiconductor devices and it establishes ideal working conditions for observing voltage contrast by scintillation detector of secondary electrons.
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Method for signal level value evaluation in ESEM
Potoma, Jaroslav ; Jirák, Josef (referee) ; Čudek, Pavel (advisor)
This work deals with problematics of enviromental scanning electron microscopy and detection of signal electrons by ionization detector.The main goal of this work is to present a comparison of osciloscopical method for evaluation of signal level with method for evaluation of signal level from grayscale of common sample images. Evaluation of advantages and disadvantages of both methods.
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Scintillation Secondary Electrons Detector for ESEM
Čudek, Pavel ; Kadlec, Jaromír (referee) ; Rek, Antonín (referee) ; Jirák, Josef (advisor)
The thesis deals with the scintillation secondary electron detector for environmental scanning electron microscope, its design and construction. The starting point was numerical simulation of electrostatic fields and electron trajectories in the electrode system of the detector and simulation of pressure distribution and flow of gases in different parts of the detector. On the basis of modeling and simulation, construction changes of the detector were gradually implemented. Detection efficiency of each version of the detector was determined by the method described in the work. This method enables to evaluate signal level from the captured images of the specimen, quality of images was stated from signal to noise ratio. The thesis describes the whole process of the detector improvement from initial state, when the detector operated with lower efficiency in the pressure range from 300 to 900 Pa, to final version that enables usage of the detector in the range from vacuum up to 1000 Pa of water vapors in the specimen chamber of the microscope.
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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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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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Detection of Signal Electrons in High Pressure Conditions in Environmental Scanning Electron Microscopy
Neděla, Vilém ; Jirák, Josef (advisor)
The thesis deals with the study of properties of a new system for detection of true secondary and backscattered electrons in high pressure conditions of the specimen chamber of a newly built environmental scanning electron microscope AQUASEM II. Detection system contains three detectors. For the first time is introduced and analyzed the working principle of ionisation detector with electrostatic separator, which is in many experiments compared with ionisation detector of secondary electrons. Experimentally demonstrated are unique properties of this detection system, especially the ability of energy separation of detected signal electrons. For the various working conditions are also analyzed signal levels detected by the BSE YAG detector, which is designed as a part of the new detection system and which worked together with both ionisation detectors.
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Scintillation SE Detector for VP SEM
Kozelský, Adam ; Čudek, Pavel (referee) ; Jirák, Josef (advisor)
This work contains description of basic properties and principles of electron microscopy focused on scanning electron microscopy. It describes construction solutions of a microscope, interaction between electron beam and sample, generation of backscattered and secondary electrons. Next chapters are dealing with development of electron microscopy and environmental scanning electron microscopy. The experimental part of this thesis is focuses on the detection of secondary electrons with scintillation detector in environmental scanning electron microscope at higher pressure in the specimen chamber. Concretely is focused on optimization of collecting grid voltage and measurement of pressure dependences.
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Multi-electrode system of ionization detector for environmental scanning electrone microscope
Uhlář, Vít ; Špinka, Jiří (referee) ; Jirák, Josef (advisor)
Thesis deals with environmental scanning electron microscopy and with detection of signal electrons by using ionization detector. First part talks about the principle of environmental scanning electron microscope. Second part describes signals generated by interaction of primary electron beam with sample. Third section explains the principle of impact ionization and ionization detector. Experimental part deals with usage of segmental ionization detector and with measuring of signal amplification from copper and platinum. Thesis also examines arrangement of electrodes of ionisation detector on material contrast and examines also on influence of voltage contrast on base - emitter junction of an NPN bipolar transistor. All experiments were carried out in dependency on saturated water vapour pressure in sample chamber.
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