TY - THES A1 - Keller, Dirk T1 - Optische Eigenschaften ZnSe-basierter zweidimensionaler Elektronengase und ihre Wechselwirkung mit magnetischen Ionen T1 - ZnSe-based QWs with a two-dimensional electron gas: Optical properties and interaction with magnetic ions N2 - In dieser Arbeit wurden nichtmagnetische und semimagnetische ZnSe-basierte Quantentröge untersucht. Im Mittelpunkt des Interesses standen hierbei vor allem die Modifikation der optischen Spektren mit einer zunehmenden Modulationsdotierung der Strukturen und der Einfluss von Spinflip-Streuungen der freien Band-Elektronen an den Mn-Ionen auf die Magnetisierung und somit die Zeeman-Aufspaltung der Strukturen. Als experimentelle Methoden wurden Photolumineszenz (PL), Photolumineszenzanregung (PLE) und Reflexionsmessungen verwendet, die in Magnetfeldern von bis zu B=48 T und bei Temperaturen im Bereich von 1.6 K bis 70 K durchgeführt wurden. Darüber hinaus wurde die Abhängigkeit der Spin-Gitter-Relaxationszeit der Mn-Ionen von der Mn-Konzentration und der Elektronengasdichte in den Quantentrögen durch zeitaufgelöste Lumineszenzmessungen untersucht. Der Einfluss eines Gradienten in der s/p-d-Austauschwechselwirkung auf die Diffusion der Ladungsträger bildet einen weiteren Schwerpunkt dieser Arbeit. Als experimentelle Methode wurde hierbei ortsaufgelöste Lumineszenz verwendet. N2 - In the present work, nonmagnetic and semimagnetic ZnSe based quantum wells were studied. The thesis was focussed on the modification of optical spectra with an increasing modulation-doping of the structures. Further emphasis was placed on the influence of the spinflip scattering of the free carriers and the Mn ions on the magnetization and thus the giant Zeeman splitting of the structures. As experimental methods, photoluminescence spectroscopy (PL), photoluminescence excitation spectroscopy (PLE) and reflection measurements were used and were performed in magnetic fields up to B=48 T and at temperatures within the range of 1.6 K to 70 K. In addition, the dependence of the spin-lattice relaxation time of the Mn ions on the Mn concentration and the electron density was examined by time-resolved luminescence spectroscopy. The influence of a gradient in the s/p-d-exchange interaction on the diffusion of carriers was studied by spatially resolved luminescence spectroscopy. KW - Zinkselenid KW - Dimension 2 KW - Elektronengas KW - Optische Eigenschaft KW - Manganselenide KW - Quantenwell KW - Elektronenstreuung KW - Spin flip KW - Manganion KW - Quantentrog KW - Magneto-optische Eigenschaften KW - 2DEG KW - Exziton KW - Spinflip-Streuung KW - quantum wells KW - magneto-optical properties KW - 2DEG KW - excitons KW - spinflip scattering Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-14774 ER - TY - JOUR A1 - Ryczko, K. A1 - Misiewicz, J. A1 - Hofling, S. A1 - Kamp, M. A1 - Sęk, G. T1 - Optimizing the active region of interband cascade lasers for passive mode-locking JF - AIP Advances N2 - The work proposes possible designs of active regions for a mode-locked interband cascade laser emitting in the mid infrared. For that purpose we investigated the electronic structure properties of respectively modified GaSb-based type II W-shaped quantum wells, including the effect of external bias in order to simultaneously fulfil the requirements for both the absorber as well as the gain sections of a device. The results show that introducing multiple InAs layers in type II InAs/GaInSb quantum wells or introducing a tensely-strained GaAsSb layer into “W-shaped” type II QWs offers significant difference in optical transitions’ oscillator strengths (characteristic lifetimes) of the two oppositely polarized parts of such a laser, being promising for utilization in mode-locked devices. KW - physics KW - electrostatics KW - transition radiation KW - oscillator strengths KW - laser spectroscopy KW - optical spectroscopy KW - atomic and molecular spectroscopy, KW - frequency combs KW - quantum wells KW - laser physics Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-181790 VL - 7 IS - 1 ER - TY - JOUR A1 - Rudno-Rudziński, W. A1 - Syperek, M. A1 - Andrezejewski, J. A1 - Maryński, A. A1 - Misiewicz, J. A1 - Somers, A. A1 - Höfling, S. A1 - Reithmaier, J. P. A1 - Sęk, G. T1 - Carrier delocalization in InAs/InGaAlAs/InP quantum-dash-based tunnel injection system for 1.55 μm emission JF - AIP Advances N2 - We have investigated optical properties of hybrid two-dimensional-zero-dimensional (2D-0D) tunnel structures containing strongly elongated InAs/InP(001) quantum dots (called quantum dashes), emitting at 1.55 μm. These quantum dashes (QDashes) are separated by a 2.3 nm-width barrier from an InGaAs quantum well (QW), lattice matched to InP. We have tailored quantum-mechanical coupling between the states confined in QDashes and a QW by changing the QW thickness. By combining modulation spectroscopy and photoluminescence excitation, we have determined the energies of all relevant optical transitions in the system and proven the carrier transfer from the QW to the QDashes, which is the fundamental requirement for the tunnel injection scheme. A transformation between 0D and mixed-type 2D-0D character of an electron and a hole confinement in the ground state of the hybrid system have been probed by time-resolved photoluminescence that revealed considerable changes in PL decay time with the QW width changes. The experimental discoveries have been explained by band structure calculations in the framework of the eight-band k·p model showing that they are driven by delocalization of the lowest energy hole state. The hole delocalization process from the 0D QDash confinement is unfavorable for optical devices based on such tunnel injection structures. KW - physics KW - surface collisions KW - electronic coupling KW - transition radiation KW - time-resolved photoluminescence KW - photoluminescence excitation KW - modulation spectroscopy KW - quantum dots KW - quantum wells KW - delocalization Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-181787 VL - 7 IS - 1 ER -