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: 9

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

Free Carrier Scattering in Metallic n-GaAs in the Presence of Static Lattice Distortions Due to a Partial Chemical Order of Impurities

100%
Słupiński T., Molas M., Papierska J.
Acta Physica Polonica A
|
2009
|
vol. 116
|
issue 5
979-982
EN
Simple electric transport versus T = 20-400 K in metallic n-GaAs annealed single crystals with Te impurity concentration ∿(0.4-1.7) × 10^{19} cm^{-3}, which is above the equilibrium doping limit, is reported and compared with modern theory of electron mobility in degenerated n-GaAs by Szmyd, Hanna, Majerfeld. An overcome of the equilibrium doping limit in annealed n-GaAs is manifested by a lowered electrical activation of Te donors and by an onset of ≈ 0.1-1 μm regions of local strain in the crystal lattice known from high resolution X-ray studies. These preliminary results of transport show that the electron mobility μ(T) measured for n-GaAs with local strains is not consistent with predictions of Szmyd et al. model for any degree of compensation assumed. This surprising result indicates that electric transport in materials above the equilibrium doping limit is not well understood assuming the scattering by ionized impurities. The nature of defects responsible for an observed strong reduction of free carrier concentration (here ≈ 80%) in annealed heavily doped n-GaAs seems not to be related with electrical compensation. We point here at the possible role of effects of free carrier scattering due to static lattice distortions (local strains) related to a chemical aggregation of impurity atoms. We also notice that transport in metallic n-GaAs with local strains shows features similar to a weak localization σ_{xx} ∝ log T.
2
Content available remote

Intershell Exchange Interaction in Charged GaAlAs Quantum Dots

100%
Molas M., Nicolet A., Potemski M., Babiński A.
Acta Physica Polonica A
|
2013
|
vol. 124
|
issue 5
785-787
EN
Optical anisotropy of charged excitons and biexcitons related to the single-particle s- and p-shell emission in GaAlAs/AlAs quantum dots is investigated. The polarization-dependence and time-resolved micro-photoluminescence measurements were performed. Cross-correlation measurements were used to identify the ladder of excitonic states and allowed us to show two cascade pathways, including the spin singlet and triplet states of charged excitons and biexcitons. The fine structure of the studied states is described and analysed in terms of electron-electron, hole-hole, and electron-hole exchange interactions.
3
Content available remote

Magnetic Field Effect on the Excitation Spectrum of a Neutral Exciton in a Single Quantum Dot

88%
Molas M., Nicolet A., Piętka B., Babiński A., Potemski M.
|
|
vol. 126
|
issue 5
1066-1068
EN
Excitation-energy-dependent magnetospectroscopic measurements of a single GaAlAs/AlAs quantum dot were performed. A significant effect of the excitation energy on the photoluminescence spectra is reported. The photoluminescence excitation spectroscopy has been used to investigate the excitation spectrum of a single electron-hole pair - a neutral exciton in magnetic field up to 14 T. The observed resonances exhibit diamagnetic shift characteristic of an s-shell related emission. In our opinion, the creation of excited complexes involving an excited hole and a ground electron is responsible for the process.
4
Content available remote

Fine Structure of Neutral Excitons in Single GaAlAs Quantum Dots

88%
Molas M., Gołasa K., Piętka B., Potemski M., Babiński A.
Acta Physica Polonica A
|
2012
|
vol. 122
|
issue 6
988-990
EN
Optical anisotropy of neutral excitons in GaAlAs/AlAs quantum dots is investigated. Low-temperature polarization-sensitive photoluminescence measurements of single quantum dots are performed. It is found that neutral excitons (X) in the quantum dots exhibit a fine structure splitting. The fine structure splitting ranges from 10 μeV to 100 μeV and correlates with the X energy. The polarization axis of the fine structure splitting is well oriented along [110] crystallographic direction of a substrate. The orientation is attributed to the elongation of GaAlAs/AlAs quantum dots in the [110] direction of the substrate.
5
Content available remote

Quantum Confinement in InAs/GaAs Systems with Self-Assembled Quantum Dots Grown Using In-Flush Technique

88%
Molas M., Kuldová K., Borysiuk J., Wasilewski Z., Babiński A.
Acta Physica Polonica A
|
2011
|
vol. 119
|
issue 5
624-626
EN
The effect of In-flush technique application to the MBE-grown structure with self-assembled quantum dots is investigated in this work. The microphotoluminescence from structures with the InAs/GaAs dots grown with and without the In-flush has been investigated. We focus our attention on "not fully developed" dots, which can be clearly distinguished in the spectrum. The dots have also been identified in the transmission electron microscopy analysis of the structures. The In-flush does not influence a broad energy range of those features. Instead we have found that the anisotropic exchange energy splitting of neutral excitons confined in those in the structure grown with In-flush is substantially lower that the splitting in the structure with no In-flush. This observation confirms that the In-flush leads not only to better uniformity of self-assembled quantum dots but also to reduction of lateral potential, anisotropy, which is believed to result in the neutral exciton splitting.
6
Content available remote

The Fine Structure of a Triexciton in Single InAs/GaAs Quantum Dots

76%
Molas M., Gołasa K., Furman M., Lapointe J., Wasilewski Z., Potemski M., Babiński A.
Acta Physica Polonica A
|
2012
|
vol. 122
|
issue 6
991-993
EN
Results of experimental study of multiexcitonic emission related to the p-shell of single self-assembled InAs/GaAs quantum dots are presented. Optical properties of a first emission line to appear from the p-shell of a strongly excited quantum dots are investigated using low-temperature polarization-sensitive micro-photoluminescence measurements. The emission line is attributed to the recombination of a complex of three electrons and holes confined in a dot (neutral triexciton), 3X. It is found that the emission consists of two linearly polarized components and the fine structure splitting is larger than the respective splitting of a neutral exciton. The optical anisotropy of the 3X emission is related to the anisotropy of the quantum dot localizing potential. The axis of the 3X optical anisotropy changes from dot to dot covering broad range within ± 50 degrees with respect to the axis defined by the optical anisotropy of a neutral exciton (X). Possible origin of the deviation is discussed.
7
Content available remote

Strong Photoluminescence Fluctuations in Laser-Thinned Few-Layer WS₂

76%
Bala Ł., Łacińska E., Nogajewski K., Molas M., Wysmołek A., Potemski M.
Acta Physica Polonica A
|
2016
|
vol. 130
|
issue 5
1176-1178
EN
We present results of μ-Raman and μ-photoluminescence study of few-layer WS₂ flakes that have been locally thinned down by a focused laser beam. The Raman spectroscopy measurements prove that the investigated flake was locally thinned down to a monolayer. Interestingly, μ-photoluminescence experiments allowed us to observe huge intensity fluctuations at the boundary of laser-thinned region. Similar effects were found at the edges of a WS₂ bilayer flake, which has not been subjected to laser-thinning. The origin of the observed time evolution of the photoluminescence response is discussed in terms of potential fluctuations resulting from light-induced changes of the charge state of defects.
8
Content available remote

The Effect of Substrate on Vibrational Properties of Single-Layer MoS₂

76%
Gołasa K., Molas M., Nogajewski K., Grzeszczyk M., Zinkiewicz M., Potemski M., Babiński A.
Acta Physica Polonica A
|
2016
|
vol. 130
|
issue 5
1172-1175
EN
We report on the Raman scattering from single-layer molybdenum disulfide (MoS₂) deposited on various substrates: Si/SiO₂, hexagonal boron nitride (h-BN), sapphire, as well as suspended. Room temperature Raman scattering spectra are investigated under both resonant (632.8 nm) and non-resonant (514.5 nm) excitations. A rather weak influence of the substrate on the Raman scattering signal is observed. The most pronounced, although still small, is the effect of h-BN, which manifests itself in the change of energy positions of the E' and A'₁ Raman modes of single-layer MoS₂. We interpret this modification as originating from van der Waals interaction between the MoS₂ and h-BN layers.
9
Content available remote

Properties of Excitons in Quantum Dots with a Weak Confinement

52%
Gołasa K., Molas M., Goryca M., Kazimierczuk T., Smoleński T., Koperski M., Golnik A., Kossacki P., Potemski M., Wasilewski Z., Babiński A.
Acta Physica Polonica A
|
2013
|
vol. 124
|
issue 5
781-784
EN
Statistical properties of neutral excitons, biexcitons and trions confined to natural quantum dots formed in the InAs/GaAs wetting layer are reported. The correlation of the trion binding energy and the biexciton binding energy was found. Magnetospectroscopic measurements of the excitons revealed also the correlation of excitonic effective g^* factor of an exciton with the biexciton binding energy. The qualitative picture of the effect of quantum confinement on the observed correlations is presented.
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.