Showing papers by "Jan Misiewicz published in 2017"
TL;DR: Applying pulsed p-shell resonant excitation results in strong suppression of multiphoton events evidenced by the as measured value of the second-order correlation function at zero delay of 0.03.
Abstract: We report on the experimental demonstration of triggered single-photon emission at the telecom O-band from In(Ga)As/GaAs quantum dots (QDs) grown by metal-organic vapor-phase epitaxy. Micro-photoluminescence excitation experiments allowed us to identify the p-shell excitonic states in agreement with high excitation photoluminescence on the ensemble of QDs. Hereby we drive an O-band-emitting GaAs-based QD into the p-shell states to get a triggered single photon source of high purity. Applying pulsed p-shell resonant excitation results in strong suppression of multiphoton events evidenced by the as measured value of the second-order correlation function at zero delay of 0.03 (and ~0.005 after background correction).
31 citations
TL;DR: In this paper, the authors investigate theoretically and experimentally epitaxial nanostructures offering a full range of confinement regimes for excitons due to controlled cross-sectional sizes and strong variation in the elongation of the nanosize objects - from strong through intermediate to weak confinement.
Abstract: The authors investigate theoretically and experimentally epitaxial nanostructures offering a full range of confinement regimes for excitons due to controlled cross-sectional sizes and strong variation in the elongation of the nanosize objects - from strong through intermediate to weak confinement. It is demonstrated that the symmetry breaking leads to significantly slower recombination in one of the bright states of the excitonic fine structure. The respective components are detected in time-resolved decays of unpolarized photoluminescence,which allows a full characterization of the exciton states, including their intrinsic polarization properties.
31 citations
TL;DR: In this paper, the surface Fermi level of Ga-polar GaN exhibits a bistable behavior allowing it to be located at two distinct energetic positions at the air/GaN interface.
31 citations
TL;DR: In this article, the authors investigated the exciton and biexciton confinement regimes in strongly anisotropic epitaxial InAs nanostructures called quantum dashes (QDashes) embedded in an In0.53Ga0.23Al0.24As matrix, which is lattice-matched to InP(001) substrate.
Abstract: The exciton and biexciton confinement regimes in strongly anisotropic epitaxial InAs nanostructures called quantum dashes (QDashes) embedded in an In0.53Ga0.23Al0.24As matrix, which is lattice-matched to InP(001) substrate, have been investigated. For that purpose, we have performed low-temperature spatially and polarization-resolved photoluminescence and time-resolved photoluminescence measurements on a set of single QDashes. The main conclusions are drawn based on the experimentally obtained distribution of the ratio between the exciton and biexciton lifetimes. We have found that a majority of QDashes for which the abovementioned ratio falls into the range of 1.2 ± 0.1–1.6 ± 0.1 corresponds to the so called intermediate confinement regime, whereas for several cases, it is close to 1 or 2, suggesting reaching the conditions of weak and strong confinement, respectively. Eventually, we support this data with dependence of the lifetimes' ratio on the biexciton binding energy, implying importance of Coulomb ...
12 citations
TL;DR: In this paper, the authors 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.
Abstract: 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 ...
11 citations
TL;DR: A.A. Strittmatterc,†, S.Rodt, the authors, S.Ryczko, P.Mrowiński, K.Musiał, J. Misiewicz, D.M. Rodt and G. Sęka,
Abstract: A. Maryński, P. Mrowiński, K. Ryczko, P. Podemski, K. Gawarecki, A. Musiał, J. Misiewicz, D. Quandt, A. Strittmatterc,†, S. Rodt, S. Reitzenstein and G. Sęka,∗ Laboratory for Optical Spectroscopy of Nanostructures, Department of Experimental Physics, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland Department of Theoretical Physics, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland Institute of Solid State Physics, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin, Germany
10 citations
TL;DR: In this paper, the authors investigated the electronic structure properties of 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.
Abstract: 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.
8 citations
TL;DR: In this article, the European Commission's Horizon 2020 Research and Innovation Programme iCspec under grant agreement No. 636930 and has also been supported by the National Science Centre of Poland within Grant No. 2014/15/B/ST7/04663.
Abstract: This project has received funding from the European Commission's Horizon 2020 Research and Innovation Programme iCspec under grant agreement No. 636930 and has also been supported by the National Science Centre of Poland within Grant No. 2014/15/B/ST7/04663.
7 citations
TL;DR: In this paper, the influence of europium on the microstructure of TiO2 was determined based on the results of X-ray diffraction, transmission electron microscopy, Raman spectroscopy and photoluminescence measurements.
Abstract: In this work modification of TiO2 thin films structure by doping with europium was described. Nanocrystalline films were prepared by high energy magnetron sputtering process. The influence of europium on the microstructure of TiO2 was determined based on the results of X-ray diffraction, transmission electron microscopy, Raman spectroscopy and photoluminescence measurements. It was found that undoped film had rutile structure directly after deposition (without additional annealing), while 0.2 at.% and 0.4 at.% of the dopant was sufficient to receive TiO2 films with anatase form. The type of structure was confirmed with the aid of Raman spectroscopy and by TEM observations. The amount of Eu-dopant had direct impact on PL intensity as well as presence of defect (voids) in the film.
7 citations
TL;DR: In this article, the lateral carrier diffusion process in coupled InGaAs/GaAs quantum dot-quantum well (QD-QW) structures was investigated by means of spatially resolved photoluminescence spectroscopy at low temperature.
Abstract: The lateral carrier diffusion process is investigated in coupled InGaAs/GaAs quantum dot-quantum well (QD-QW) structures by means of spatially resolved photoluminescence spectroscopy at low temperature. Under non-resonant photo-excitation above the GaAs bandgap, the lateral carrier transport reflected in the distorted electron-hole pair emission profiles is found to be mainly governed by high energy carriers created within the 3D density of states of GaAs. In contrast, for the case of resonant excitation tuned to the QW-like ground state of the QD-QW system, the emission profiles remain unaffected by the excess kinetic energy of carriers and local phonon heating within the pump spot. The lateral diffusion lengths are determined and present certain dependency on the coupling strength between QW and QDs. While for a strongly coupled structure the diffusion length is found to be around 0.8 μm and monotonically increases up to 1.4 μm with the excitation power density, in weakly coupled structures, it is deter...
7 citations
TL;DR: Both core types of NPs (Y-core and Gd-core) impaired the phagocytic activity of monocytes the strongest, having minimal or none whatsoever influence on granulocytes and respiratory burst of phagocyte cells; however, some cause toxic effects (they have statistically significant deviations compared to reference) in some selected doses tested.
Abstract: Sodium fluoride-based β-NaLnF4 nanoparticles (NPs) doped with lanthanide ions are promising materials for application as luminescent markers in bio-imaging. In this work, the effect of NPs doped with yttrium (Y), gadolinium (Gd), europium (Eu), thulium (Tm), ytterbium (Yb) and terbium (Tb) ions on phagocytic activity of monocytes and granulocytes and the respiratory burst was examined. The surface functionalization of <10-nm NPs was performed according to our variation of patent pending ligand exchange method that resulted in meso-2,3-dimercaptosuccinic acid (DMSA) molecules on their surface. Y-core-based NCs were doped with Eu ions, which enabled them to be excited with UV light wavelengths. Cultures of human peripheral blood (n = 8) were in vitro treated with five different concentrations of eight NPs for 24 h. In summary, neither type of nanoparticles is found toxic with respect to conducted test; however, some cause toxic effects (they have statistically significant deviations compared to reference) in some selected doses tested. Both core types of NPs (Y-core and Gd-core) impaired the phagocytic activity of monocytes the strongest, having minimal or none whatsoever influence on granulocytes and respiratory burst of phagocytic cells. The lowest toxicity was observed in Gd-core, Yb, Tm dopants and near-infrared nanoparticles. Clear dose-dependent effect of NPs on phagocytic activity of leukocytes and respiratory burst of cells was observed for limited number of samples.
TL;DR: In this article, Mrowiński, Dusanowski and Sęka this article proposed a method to solve the problem of complex material systems in Wrocław.
Abstract: P. Mrowiński, Ł. Dusanowski, A. Somers, S. Höfling, J.P. Reithmaier, J. Misiewicz and G. Sęka,∗ OSN Lab, Department of Experimental Physics, Faculty of Fundamental Problems of Technology, Wrocław University of Science Technology, Wrocław, Poland Technische Physik & W.C. Röntgen-Center for Complex Material Systems, Universität Würzburg, Germany School of Physics and Astronomy, University of St. Andrews, St. Andrews, United Kingdom Institute of Nanostructure Technologies and Analytics, Technische Physik, Universität Kassel, Germany Institute of Nanostructure Technologies and Analytics (INA), CINSaT, University of Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
TL;DR: In this paper, temperature-resolved photoluminescence studies were performed on tensely-strained AlSb/InAs/GaAsSb W-shaped type II quantum wells.
Abstract: Temperature-resolved photoluminescence studies were performed on tensely-strained AlSb/InAs/GaAsSb W-shaped type II quantum wells. They revealed two emission bands: one at lower energy of localized origin resulting from carrier trapping states at interfaces and dominates at low-temperature; and one corresponding to the fundamental optical transition in the type II quantum well. With the temperature increase to 170–200 K the low-energy emission is quenched and the high-energy band dominates and its intensity increases, indicating carrier transfer processes between the respective states at elevated temperatures. In addition, the integrated photoluminescence intensity was measured as a function of excitation power. At high excitation regime the emission intensity of the low-energy emission band saturated, indicating low density of states, thus confirming its localized nature. The depth of the localization potential at the InAs/GaAsSb interface was determined to be 13–15 meV.
01 Oct 2017
TL;DR: In this paper, the issue of quantum mechanical coupling between a semiconductor quantum dot and a quantum well is studied in two families of GaAs- and InP-based structures at cryogenic temperatures.
Abstract: The issue of quantum mechanical coupling between a semiconductor quantum dot and a quantum well is studied in two families of GaAs- and InP- based structures at cryogenic temperatures. It is shown that by tuning the quantum well parameters one can strongly disturb the 0D-character of the coupled system ground state, initially located in a dot. The out-coupling of either an electron or a hole state from the quantum dot confining potential is viewed by a significant elongation of the photoluminescence decay time constant. Band structure calculations show that in the GaAs-based coupled system at its ground state a hole remains isolated in the dot, whereas an electron gets delocalized towards the quantum well. The opposite picture is built for the ground state of a coupled system based on InP.
01 Oct 2017