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Study of CdTe sensor properties
Vašíček, Martin ; Holcman, Vladimír (referee) ; Grmela, Lubomír (advisor)
This Bachelor Thesis is focused on studies of CdTe detector characteristics. It is to describe the analysis of transport and noise characteristics of CdTe samples at different temperatures. Evaluation of our results proves that CdTe junction behaves like an antiseries connection of a pair of diodes. The courses of VA characteristics are noted for linear or slightly exponential growth. When temperature is growing , conductivity of the samples is growing too. Our measurements demonstrated difference in conductivity of samples tested at the same temperature. It is also obvious that within very low range of frequencies the factor of noise 1/f is dominating. From 10Hz frequency the effect of thermal noise prevails.
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Analysis of noise characteristics of radioactive emission detectors
Šik, Ondřej ; Pfeifer, Václav (referee) ; Andreev, Alexey (advisor)
The main goal of this Master’s thesis is to describe relationship between low frequency noise spectral characteristics of Cadmium-Telluride radiation detectors depending on applied voltage and detectors reaction to illumination of various wavelengths. Also, the reaction and influence of higher operating temperatures were investigated. The noise measurements shown that the dominant noise type at low frequencies is the 1/f noise. Several samples with different resistivity were tested. By comparing results, we are able to estimate the quality of detectors and their sensibility to illumination and higher operating temperatures. We have found that all the studied CdTe detectors are sensitive to one particular wavelength of 548nm. Resulting data were processed by EasyPlot program that provided graphical representation of spectral noise characteristics. All measured characteristics of tested samples are compared and it’s estimated the similarity between the samples.
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Study of CdTe sensor properties
Vašíček, Martin ; Holcman, Vladimír (referee) ; Grmela, Lubomír (advisor)
This Bachelor Thesis is focused on studies of CdTe detector characteristics. It is to describe the analysis of transport and noise characteristics of CdTe samples at different temperatures. Evaluation of our results proves that CdTe junction behaves like an antiseries connection of a pair of diodes. The courses of VA characteristics are noted for linear or slightly exponential growth. When temperature is growing , conductivity of the samples is growing too. Our measurements demonstrated difference in conductivity of samples tested at the same temperature. It is also obvious that within very low range of frequencies the factor of noise 1/f is dominating. From 10Hz frequency the effect of thermal noise prevails.
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Radiation Detectors Noise Spectroscopy
Andreev, Alexey ; Grmela, Lubomír (advisor)
Kadmium telurid je velmi důležitý materiál jak základního, tak i aplikovaného výzkumu. Je to dáno zejména jeho výhodnými elektronickými, optickými a strukturními vlastnostmi, které ho předurčují pro náročné technické aplikace. Dnes se hlavně používá pro jeho vysoké rozlišení k detekci a X-záření. Hlavní výhodou detektorů na bázi CdTe je, že nepotřebují chlazení a mohou spolehlivě fungovat i při pokojové teplotě. To způsobuje efektivnější interakce fotonů než je tomu u Si nebo jiných polovodičových materiálů. Obsahem této práce byla analýza a interpretace výsledků získaných studiem šumových a transportních charakteristik CdTe vzorků. Měření ukázaly že odpor homogenní části CdTe krystalů mírně klesá při připojení elektrického pole na vzorku. Při změně teploty navíc dochází k odlišné reakci u CdTe typu p a n. Právě těmto efektům je v práci věnována pozornost. Pomocí šumové spektroskopie bylo zjištěno, že při nízkých frekvencích je u vzorků dominantní šum typu 1/f, zatímco při vyšších frekvencích je sledován generačně-rekombinační šum a tepelný šum. Všechny měřené vzorky vykazovaly mnohem vyšší hodnotu šumu na nízkých frekvencích než udává Hoogeova rovnice. Byly nalezeny a popsány zdroje nadbytečného šumu.
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Analysis of noise characteristics of radioactive emission detectors
Šik, Ondřej ; Pfeifer, Václav (referee) ; Andreev, Alexey (advisor)
The main goal of this Master’s thesis is to describe relationship between low frequency noise spectral characteristics of Cadmium-Telluride radiation detectors depending on applied voltage and detectors reaction to illumination of various wavelengths. Also, the reaction and influence of higher operating temperatures were investigated. The noise measurements shown that the dominant noise type at low frequencies is the 1/f noise. Several samples with different resistivity were tested. By comparing results, we are able to estimate the quality of detectors and their sensibility to illumination and higher operating temperatures. We have found that all the studied CdTe detectors are sensitive to one particular wavelength of 548nm. Resulting data were processed by EasyPlot program that provided graphical representation of spectral noise characteristics. All measured characteristics of tested samples are compared and it’s estimated the similarity between the samples.
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