|
|
Photo-Hall effect spectroscopy and laser-induced transient currents in CdTe-based semiconductor radiation detectors
Musiienko, Artem ; Grill, Roman (advisor) ; Dubecký, František (referee) ; Oswald, Jiří (referee)
Title: Photo-Hall effect spectroscopy and laser-induced transient currents in CdTe-based semiconductor radiation detectors Author: Artem Musiienko Department / Institute: Institute of Physics, Faculty of Mathematics and Physics, Charles University Supervisor of the doctoral thesis: Prof. RNDr. Roman Grill, CSc, Institute of Physics, Faculty of Mathematics and Physics, Charles University Abstract: Cadmium Telluride, Cadmium Zinc Telluride, and Cadmium Manganese Telluride are important semiconductors with applications in radiation detection, solar cells, and electro-optic modulators. Their electrical and optical properties are principally controlled by defects forming energy levels within the bandgap. Such defects create recombination and trapping centers capturing photo- created carriers and depreciating the performance of the detector. Simultaneously, the changed occupancy of levels leads to the charging of detector's bulk, which results in the screening of applied bias and the loss of detector's sensitivity. Detailed knowledge of crystal defect structure is thus necessary for the predictable detector work and also for the possibility to reduce the structural defects concentration. This thesis reports on the investigation of deep energy levels in CdTe-based high resistivity and detector-grade materials by...
|
|
|
Zeemanův jev v polovodičových kvantových strukturách
Stráský, Josef ; Grill, Roman (advisor) ; Výborný, Karel (referee)
This theoretical thesis presents detailed study of negatively charged excitons - trions - confined in single quantum well in presence of perpendicular magnetic field. Complex valence band of GaAs/GaAlAs compound is described within Luttinger Hamiltonian framework. Singlet and triplet states of negative trion are introduced. Advanced theoretical analysis of Zeeman effect for different states of trion is performed. Landau gauge of magnetic field and unusual wavefunctions basis is chosen and its accuracy is tested. Evolution of ground state energy and photoluminescence spectra with magnetic field is evaluated for different values of Landé g-factors. Probability of occurrence of electrons with respect to the hole position and their spatial correlation function are investigated.
|
|
| |
|
| |
|
|
Electromigration of defects in (CdZn)Te single crystals.
Pekárek, Jakub ; Belas, Eduard (advisor) ; Grill, Roman (referee)
In the present work we study effect of electromigration of defects in CdTe material in external electric field at various temperatures and biases. The aim was to verify this effect using a set of electric contacts arranged linearly along the sample. These contacts as a potential probes was used for the detection of the drift of the local resistance modulation. We try to determine under what conditions and why it happens and then decide how this effect can be used for purification of semi-conducting samples and for preparation of semi-insulating material.
|
|
| |
|
| |
|
| |
|
|
Magnetooptical properties of semiconductor quantum structures
Uxa, Štěpán ; Grill, Roman (advisor)
Title: Magnetooptical Properties of Semiconductor Quantum Structures Author: Štěpán Uxa Department: Institute of Physics of Charles University Supervisor: Assoc. Prof. Roman Grill, PhD Supervisor's e-mail address: grill@karlov.mff.cuni.cz Abstract: In this theoretical work, a detailed study of optical properties of excitons in double quantum wells subject to magnetic and electric fields is presented. Starting from the well-known Luttinger formulae describing the real valence-band structure of III-V semi- conductor compounds, we developed an efficient way to solve the Schrödinger equation of a coulombically-bound pair electron-hole forming an exciton. Derived formulae were illus- trated on relevant figures, giving us an opportunity to better understand the effects of external fields on the studied system. Dispersion relations, the shift of energy levels in an electric field, absorption and photoluminescence spectra, and charge density distribution were calculated and achieved results were discussed in detail. Keywords: exciton, double quantum well, coupled quantum wells, Luttinger (-Kohn) hamiltonian, valence-subband mixing
|
|
|
Photo-Hall effect spectroscopy and laser-induced transient currents in CdTe-based semiconductor radiation detectors
Musiienko, Artem ; Grill, Roman (advisor)
Title: Photo-Hall effect spectroscopy and laser-induced transient currents in CdTe-based semiconductor radiation detectors Author: Artem Musiienko Department / Institute: Institute of Physics, Faculty of Mathematics and Physics, Charles University Supervisor of the doctoral thesis: Prof. RNDr. Roman Grill, CSc, Institute of Physics, Faculty of Mathematics and Physics, Charles University Abstract: Cadmium Telluride, Cadmium Zinc Telluride, and Cadmium Manganese Telluride are important semiconductors with applications in radiation detection, solar cells, and electro-optic modulators. Their electrical and optical properties are principally controlled by defects forming energy levels within the bandgap. Such defects create recombination and trapping centers capturing photo- created carriers and depreciating the performance of the detector. Simultaneously, the changed occupancy of levels leads to the charging of detector's bulk, which results in the screening of applied bias and the loss of detector's sensitivity. Detailed knowledge of crystal defect structure is thus necessary for the predictable detector work and also for the possibility to reduce the structural defects concentration. This thesis reports on the investigation of deep energy levels in CdTe-based high resistivity and detector-grade materials by...
|
guest ::
RSS feed.