Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 16

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Content available remote

Optically Detected SdH Oscillations in CdTe/(CdMg)Te and CdTe/(CdMnMg)Te Modulation Doped Quantum Wells

100%
Shen J. X., Ossau W., Fischer F., Waag A., Landwehr G.
Acta Physica Polonica A
|
1995
|
vol. 88
|
issue 5
1033-1037
EN
Oscillations of photoluminescence properties in external magnetic fields are investigated in CdTe modulation doped quantum wells. The oscillatory behaviour of the luminescence intensity, the line width and the g factor is due to many-body effects in the 2-dimensional electron gas. The oscillation of photoluminescence intensity can be easily used as optically detected Shubnikov de Haas effect to determine the electron concentration in quantum wells without contacts.
2
Content available remote

Effect of Magnetic Polaron Formation on the Exciton Mobility Edge in Cd_{1-x}Mn_{x}Te

100%
Mackh G., Yakovlev D., Ossau W., Waag A., Landwehr G.
Acta Physica Polonica A
|
1995
|
vol. 87
|
issue 1
265-268
EN
We study the exciton localization in the semimagnetic semiconductor Cd_{1-x}Mn_{x}Te by selective excitation of the exciton photoluminescence. We show that the energy position of the effective mobility edge for excitons is subject to the competition between nonmagnetic and magnetic localization due to the magnetic polaron formation. External magnetic fields affect this competition by suppressing the polaron formation, which shifts the mobility edge.
3
Content available remote

Characterization of Interfaces in Semimagnetic Quantum Wells

86%
Schmitt G., Kuhn-Heinrich B., Zehnder U., Ossau W., Litz T., Waag A., Landwehr G.
Acta Physica Polonica A
|
1995
|
vol. 88
|
issue 5
897-900
EN
The interfaces between nonmagnetic CdTe quantum wells and semimagnetic barriers of Cd_{1-x}Mn_{x}Te were investigated for several well widths by low temperature photoluminescence and photoluminescence excitation spectroscopy. Specially designed Cd_{1-x}Mn_{x}Te/CdTe/Cd_{1-y}Mg_{y}Te structures enable us to distinguish the quality of the semimagnetic normal and inverted interfaces. The normal interface shows to have a better structural quality than the inverted interface.
4
Content available remote

Dimensional Dependence of Exchange Interactions at High Magnetic Fields

86%
Zehnder U., Kuhn-Heinrich B., Ossau W., Waag A., Landwehr G., Cheng H., Nicholas R.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 5
989-992
EN
We studied the contribution of the breaking of antiferromagnetically coupled spin clusters to the total magnetization in thin (CdMn)Te layers as a function of the layer thickness by reflectivity spectroscopy in magnetic fields up to 45 T. The experimental results show that the contribution of the breaking of antiferromagnetically coupled spin clusters is reduced by decreasing layer thickness.
5
Content available remote

Exciton Magnetic Polaron Features in Photoluminescence Excitation Spectra of CdTe/(CdMn)Te Quantum Wells with High Mn Contents

86%
Mackh G., Ossau W., Yakovlev D. R., Landwehr G., Wojtowicz T., Karczewski G., Kossut J.
Acta Physica Polonica A
|
1995
|
vol. 88
|
issue 5
849-852
EN
Exciton magnetic polarons are studied in CdTe/Cd_{1-x}Mn_{x}Te (0.4 ≤ x ≤ 0.8) quantum wells. The magnetic polaron formation leads to the appearance of an additional line in the photoluminescence excitation spectra, which can be employed to determine the Zeeman splittings more exactly than by using the free exciton peak. We find an overall increase in the polaron energy with increasing x in the whole range of Mn contents studied.
6
Content available remote

Lateral Spin Diffusion Probed by Two-Color Hanle-MOKE Technique

86%
Quast J., Astakhov G., Ossau W., Molenkamp L., Heinrich J., Höfling S., Forchel A.
Acta Physica Polonica A
|
2008
|
vol. 114
|
issue 5
1311-1316
EN
We report on all optical spatially resolved spin diffusion experiments in an unstrained, unbiased n-GaAs layer. Optical pump and probe intensities are varied over a wide range to study the impact of optical disturbance on spin transport. Both quantities have a considerable influence on the measured spin diffusion length and spin lifetime. Furthermore, an effective spin diffusion coefficient was obtained as a function of temperature.
7
Content available remote

Effect of Spin-Glass Phase Formation on Exciton Magnetic Polaron in (Cd,Mn)Te

86%
Chudnovskiy A. L., Rosenow B., Oppermann R., Yakovlev D., Zehnder U., Ossau W.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 4
755-758
EN
The influence of the spin-glass phase formation of the (Cd,Mn)Te semimagnetic layers on properties of the exciton magnetic polaron were investigated both theoretically and experimentally. The theoretical model offers a consistent description of the temperature dependence of the exciton magnetic polaron energy in the vicinity of spin-glass transition and shows good agreement with the experimental data.
8
Content available remote

Optically Detected Magnetic Resonance of Excess Electrons in CdTe/(Cd,Mg)Te Quantum Wells

86%
Hu C., Ossau W., Yakovlev D., König B., Wojtowicz T., Karczewski G., Kossut J.
Acta Physica Polonica A
|
1998
|
vol. 94
|
issue 2
351-354
EN
The spin resonance of excess electrons is observed with the detection either on the neutral or the negatively charged exciton X^{-} emission in type I CdTe/(Cd,Mg)Te quantum wells with excess electrons of low density. It is found that the electron spin-dependent and electron spin-conserving formation and recombination of X^{-} make the optical detection of the spin resonance of excess electrons feasible. For the first time, optically detected magnetic resonance is used to study fast optical transition processes in the nanosecond timescale where the microwave-induced magnetic transition rate is much lower than the optical transition rate.
9
Content available remote

Cd_{1-x}Mn_{x}Te Parabolic Quantum Wells

73%
Wojtowicz T., Kutrowski M., Cywiński G., Dynowska E., Karczewski G., Kossut J., Fiederling R., Mackh G., Zehnder U., Ossau W.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 5
977-980
EN
We report on the growth and optical studies of II-VI semiconductor parabolic quantum wells made of Cd_{1-x}Mn_{x}Te for a broad range of quantum well widths and Mn molar fractions x. Photoluminescence excitation spectra revealed several series of peaks equidistant in energy associated with interband optical transitions between harmonic oscillator levels. From the analysis of the spectra the valence band offset Q_{hh} = 0.44±0.1 was determined for the CdTe/Cd_{1-x}Mn_{x}Te system.
10
Content available remote

Optical Anisotropy of ZnSe/BeTe Superlattices Probed by Excitonic Spectroscopy

73%
Platonov A., Kochereshko V., Ivchenko E., Yakovlev D., Ossau W., Fischer F., Waag A., Landwehr G.
Acta Physica Polonica A
|
1998
|
vol. 94
|
issue 3
479-482
EN
Photoluminescence spectra of type-II ZnSe/BeTe superlattices were studied. A linear polarised photoluminescence has been found in the spectral range of spatially indirect exciton transitions. This observation is interpreted in a model of optical anisotropy of heterostructures with no-common atom at interfaces.
11
Content available remote

Investigation of Spin-Glass Transition in Semimagnetic Quantum Wells Based on Cd_{1-x}Mn_{x}Te by Means of Optical Spectroscopy

73%
Zehnder U., Yakovlev D. R., Ossau W., Waag A., Landwehr G., Wojtowicz T., Karczewski G., Kossut J.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 5
1075-1078
EN
The spin-glass transition in Cd_{1-x}Mn_{x}Te epitaxial layers and bulk samples with 0.24 ≤ x ≤ 0.43 and in quantum well structures on the basis of Cd_{1-x}Mn_{x}Te were investigated by means of optical spectroscopy. Reduction of dimensionality of Cd_{1-x}Mn_{x}Te layers down to the quasi-two-dimensional case realized in Cd_{1-x}Mn_{x}Te/Cd_{1- y}Mn_{y}Te heterostructures frustrates the spin-glass formation, which is in agreement with theoretical predictions. The spin-glass formation is also frustrated in the vicinity of interfaces between semimagnetic and nonmagnetic semiconductors in CdTe/Cd_{1-x}Mn_{x}Te quantum wells.
12
Publication available in full text mode
Content available

CdSe/ZnSe Quantum Dots Formed by Low Temperature Epitaxy and In-Situ Annealing: Properties and Growth Optimization

73%
Mahapatra S., Schumacher C., Kiessling T., Astakhov G., Bass U., Ossau W., Geurts J., Brunner K.
Acta Physica Polonica A
|
2005
|
vol. 108
|
issue 5
769-776
EN
The formation of CdSe/ZnSe quantum dots by a method combining a low temperature MBE growth of a CdSe layer and its subsequent in-situ annealing at temperatures between 280-340ºC has been studied. The thermal treatment results in a re-organization of the surface from a nearly two-dimensional layer to an ensemble of three-dimensional dot-like features. In this work we optimized the different growth and annealing parameters of this process and compared the properties of the resultant dots with those of dots grown by conventional MBE at 300ºC. It is demonstrated that the luminescence properties of the dots for both growth techniques are comparable but the areal density achieved by the in-situ annealing technique is an order of magnitude lower. From high resolution X-ray diffraction results, it could be established that no desorption takes place despite significantly long annealing duration. Beyond a nominal coverage of 3.5 ML CdSe, stacking faults are generated, leading to a gradual decrease in luminescence intensities and an overlap of pendellösung fringes in X-ray diffractograms.
13
Content available remote

Exciton States in Type-II ZnSe/BeTe Quantum Wells

73%
Platonov A. V., Yakovlev D. R., Zehnder U., Kochereshko V. P., Ossau W., Fischer F., Litz T., Waag A., Landwehr G.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 5
953-957
EN
We present an optical investigation of novel heterostructures based on beryllium chalcogenides with a type-I and type-II band alignment. In the type-II quantum well structures (ZnSe/BeTe) we observed a strong exciton transition involving an electron confined in the conduction band well and a hole localized in the valence band barrier (both in ZnSe layer). This transition is drastically broadened by the temperature increase due to enhanced exciton-acoustic phonon interaction.
14
Content available remote

Model Study of Inhomogeneous Line Broadening in Excitonic Spectra of Quantum Wells

73%
Astakhov G., Kochereshko V., Kosobukin V., Yakovlev D., Wojtowicz T., Karczewski G., Kossut J., Ossau W., Landwehr G.
Acta Physica Polonica A
|
1998
|
vol. 94
|
issue 2
235-239
EN
An approach is proposed to estimate separately parameters of homogeneous and inhomogeneous broadenings from an optical reflection line of a quasi-2D exciton. A phenomenological model is proposed to take into account statistically an inhomogeneous broadening of the exciton resonant spectra. The concept is applied to study a modulation-doped heterostructures with a single quantum well CdTe/CdMgTe. From exciton reflection lines taken in a magnetic field the temperature-dependent homogeneous and inhomogeneous broadening parameters as well as the exciton radiative decay rate are measured.
15
Content available remote

Novel CdTe/CdMgTe Graded Quantum Well Structures

73%
Wojtowicz T., Kutrowski M., Karczewski G., Cywiński G., Surma M., Kossut J., Yakovlev D. R., Ossau W., Landwehr G., Kochereshko V.
|
EN
We report on growth and magnetooptical studies of two types of novel CdTe/CdMgTe quantum well structures having a precisely controlled grading of either the quantum well width or the donor concentration in a direction perpendicular to the growth axis. The presence of two-dimensional electron gas of varying concentration produced by the graded modulation doping was evidenced by observation of negatively charged exciton-electron complexes (X¯).
16
Content available remote

Half-Parabolic Quantum Wells of Diluted Magnetic Semiconductor Cd_{1-x}Mn_{x}Te

59%
Kutrowski M., Wojtowicz T., Cywiński G., Karczewski G., Janik E., Dynowska E., Kossut J., Kossacki P., Fiederling R., Pfeuffer-Jeschke A., Ossau W.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 5
887-890
EN
We report on magnetooptical studies of MBE-grown half-parabolic CdTe/Cd_{x}Mn_{1-x}Te quantum well structures. The value of the valence band offset Q_{v}=0.4 ± 0.05 was determined by comparing energies of optical transitions in the absence of a magnetic field with model calculations. This value was verified by fitting the observed spin splitting of the lowest heavy hole (hh) state. We discuss also the temperature dependence of Q_{v}.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.