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Photoelectric spectroscopy of deep electronic levels in high-resistance CdTe
Kubát, Jan ; Franc, Jan (advisor) ; Sopko, Bruno (referee)
CdTe is one of the most interesting X-ray and g-ray detectors' material. This work deals with influence of deep levels to photoelectric properties of CdTe. PICTS, Lux-Ampere and spectral dependences measurements at room temperature and low temperature 10K were performed on one undoped and several variously doped (Cl, Sn and Ge) samples and applied electrical fields up to 800V.cm-1. Experimental setups are introduced. Room temperature numerical solution of sample photoelectrical properties for typical midgap level using driftdiffusion and Poisson equation was performed and results are discussed. The experimentally observed slopes of Lux-ampere characteristics and energy shifts of the main photoconductivity peak with the applied voltage are explained based on a model of screening of electric field by charge accumulated on deep levels. Finally comparison with acquired experimental data is performed yielding estimates of maximum total concentration of deep levels in the samples.
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Influence of the annealing on the native defects concentration in (CdZn)Te semiconductors.
Bugár, Marek ; Belas, Eduard (advisor) ; Sopko, Bruno (referee)
Paper is focused on finding an optimal annealing treatment for elimination of concentration of inclusions in (CdZn)Te. Demands for material used for MBE growth of (HgCd)Te are material without crystal imperfections, infrared transmittance above 60% and good crystalline quality. These parameters were measured by the X-ray diffraction rocking curve (XRC) method, Infrared Fourier Transform spectrometer and Infrared microscopy. The influence of annealing in the range of 600-850řC in Cd overpressure was investigated on saples contained Te-rich inclusions. The change of shape of Te-rich inclusions and infrared transmittance after annealing in Tellurium vapor was measured. The influence of annealing in Te overpressure in the range of 600-800řC was also investigated o samples contained Cd-rich inclusions, one sample was annealed in Cd overpressure.
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Photoelectric spectroscopy of deep electronic levels in high-resistance CdTe
Kubát, Jan ; Franc, Jan (advisor) ; Sopko, Bruno (referee)
CdTe is one of the most interesting X-ray and g-ray detectors' material. This work deals with influence of deep levels to photoelectric properties of CdTe. PICTS, Lux-Ampere and spectral dependences measurements at room temperature and low temperature 10K were performed on one undoped and several variously doped (Cl, Sn and Ge) samples and applied electrical fields up to 800V.cm-1. Experimental setups are introduced. Room temperature numerical solution of sample photoelectrical properties for typical midgap level using driftdiffusion and Poisson equation was performed and results are discussed. The experimentally observed slopes of Lux-ampere characteristics and energy shifts of the main photoconductivity peak with the applied voltage are explained based on a model of screening of electric field by charge accumulated on deep levels. Finally comparison with acquired experimental data is performed yielding estimates of maximum total concentration of deep levels in the samples.
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