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Detector of optical beam position
Lukáč, Vladimír ; Barcík, Peter (referee) ; Kolka, Zdeněk (advisor)
The bachelor's thesis deals with the design of an optical beam position detector with the required parameters. The aim was to select a suitable photodetector that captures light rays and converts them into photocurrent, to design photocurrent processing into a voltage signal with linear properties and specified parameters, to convert the analog form of the voltage signal into digital information with which a microcomputer or microcontroller can work. The analog part of the work is simulated in the program OrCAD PSpice, in which the functionality and correctness of the designs is confirmed. The digital part processes the voltage signal to the information of the used channel, its level displays this data on the display.
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Characterization of perovskite solar cell materials by transient techniques
Nakládal, Martin ; Zmeškal, Oldřich (referee) ; Novák, Vítězslav (advisor)
This thesis deals with the study of the lifetime of charge carriers in perovskite single crystals. The principle of perovskite solar cells is formulated, their main structures are characterized and the history of the development of perovskite solar cells is summarized, especially in terms of efficiency. The properties of perovskite single crystals with perovskite solar cells are compared. For measurement purposes, transient methods, impedance spectroscopy, load characteristics and the dependence of sensitivity and photocurrent on the wavelength of incident radiation are described. The practical part deals with the method of measuring and evaluating the lifetime of charge carriers in the investigated perovskite single crystals.
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Perovskite-based optical sensor
Frkáň, Lukáš ; Jandová, Kristýna (referee) ; Novák, Vítězslav (advisor)
The aim of this Master´s thesis is to frame the concept of perovskite-based materials, provide basic information about perovskite-based materials and scrutinize their potential in terms of optical sensors manufacturing. The thesis also deals with monitoring of the sample in terms of long-term stability. The analysis of measured characteristics and their properties is included in this semester thesis as well, along with the methodology of testing and evaluating of the results.
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Detector of optical beam position
Lukáč, Vladimír ; Barcík, Peter (referee) ; Kolka, Zdeněk (advisor)
The bachelor's thesis deals with the design of an optical beam position detector with the required parameters. The aim was to select a suitable photodetector that captures light rays and converts them into photocurrent, to design photocurrent processing into a voltage signal with linear properties and specified parameters, to convert the analog form of the voltage signal into digital information with which a microcomputer or microcontroller can work. The analog part of the work is simulated in the program OrCAD PSpice, in which the functionality and correctness of the designs is confirmed. The digital part processes the voltage signal to the information of the used channel, its level displays this data on the display.
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Perovskite-based optical sensor
Frkáň, Lukáš ; Jandová, Kristýna (referee) ; Novák, Vítězslav (advisor)
The aim of this Master´s thesis is to frame the concept of perovskite-based materials, provide basic information about perovskite-based materials and scrutinize their potential in terms of optical sensors manufacturing. The thesis also deals with monitoring of the sample in terms of long-term stability. The analysis of measured characteristics and their properties is included in this semester thesis as well, along with the methodology of testing and evaluating of the results.
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Influence of external fields on electric field and photocurrent in CdTe detectors
Rejhon, Martin ; Franc, Jan (advisor)
This thesis is focused on a study of CdTe and CdZnTe semiconductor detectors working under high flux of radiation. We studied experimentally an influence of high flux of X-rays and optical radiation on polarization of the detector. The polarization phenomenon decreases the efficiency of the detector due to a screening of an applied electric field by a space charge accumulated at deep levels due to a trapping of photogenerated carriers. In order to measure the electric field profiles in the detectors we employed a method based on cross polarizers technique and Pockels effect. The main objective of this work was to study the possibilities of an optical de-polarization of CdTe and CdZnTe detectors for different photon energies of additional light, its dynamics and physical origin. We have found that detectors can be de-polarized by above bandgap light. Moreover, CdZnTe detector can be depolarized by near infrared light and in a pulse mode. The de- polarization is associated with a compensation of the space charge at deep traps.
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Charge transport optical characterization in semiconductor radiation detectors
Ridzoňová, Katarína ; Belas, Eduard (advisor)
Measurements of DC photocurrent-voltage characteristic, photocurrents spectral response and laser induced transient current technique enable investigation of surface recombination centers, bulk trap levels and distribution of the inner electric field. In the presented work, the n- type planar CdZnTe detectors with quasi Ohmic contacts were studied by above mentioned methods. It has been shown that in the case of strongly absorbed light under the DC regime of illumination not only surface recombination influences the detector's transport properties. The effect of the space charge, created as a consequence of carriers trapped by the impurity levels, must be taken into account. Therefore some new theoretical models were created in order to describe measured photocurrent-voltage dependencies. Obtained data were fitted with the new theory and the mobility and surface recombination velocity for electrons were determined.
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Characterization of perovskite solar cell materials by transient techniques
Nakládal, Martin ; Zmeškal, Oldřich (referee) ; Novák, Vítězslav (advisor)
This thesis deals with the study of the lifetime of charge carriers in perovskite single crystals. The principle of perovskite solar cells is formulated, their main structures are characterized and the history of the development of perovskite solar cells is summarized, especially in terms of efficiency. The properties of perovskite single crystals with perovskite solar cells are compared. For measurement purposes, transient methods, impedance spectroscopy, load characteristics and the dependence of sensitivity and photocurrent on the wavelength of incident radiation are described. The practical part deals with the method of measuring and evaluating the lifetime of charge carriers in the investigated perovskite single crystals.
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Charge transport optical characterization in semiconductor radiation detectors
Ridzoňová, Katarína ; Belas, Eduard (advisor)
Measurements of DC photocurrent-voltage characteristic, photocurrents spectral response and laser induced transient current technique enable investigation of surface recombination centers, bulk trap levels and distribution of the inner electric field. In the presented work, the n- type planar CdZnTe detectors with quasi Ohmic contacts were studied by above mentioned methods. It has been shown that in the case of strongly absorbed light under the DC regime of illumination not only surface recombination influences the detector's transport properties. The effect of the space charge, created as a consequence of carriers trapped by the impurity levels, must be taken into account. Therefore some new theoretical models were created in order to describe measured photocurrent-voltage dependencies. Obtained data were fitted with the new theory and the mobility and surface recombination velocity for electrons were determined.
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Charge transport optical characterization in semiconductor radiation detectors
Ridzoňová, Katarína ; Belas, Eduard (advisor) ; Toušek, Jiří (referee)
Measurements of DC photocurrent-voltage characteristic, photocurrents spectral response and laser induced transient current technique enable investigation of surface recombination centers, bulk trap levels and distribution of the inner electric field. In the presented work, the n- type planar CdZnTe detectors with quasi Ohmic contacts were studied by above mentioned methods. It has been shown that in the case of strongly absorbed light under the DC regime of illumination not only surface recombination influences the detector's transport properties. The effect of the space charge, created as a consequence of carriers trapped by the impurity levels, must be taken into account. Therefore some new theoretical models were created in order to describe measured photocurrent-voltage dependencies. Obtained data were fitted with the new theory and the mobility and surface recombination velocity for electrons were determined.
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