Search results

1

Large Filling-Factor-Dependent Spin Splitting in Magnetooptic Kerr Effect in GaAs/AlGaAs Multiple Quantum Wells

100%

Dudziak E., Bozym J., Pruchnik D., Wasilewski Z.

Acta Physica Polonica A

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1998

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vol. 94

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issue 2

291-296

EN

Magnetooptic Kerr effect in GaAs/Al_{0.312}Ga_{0.688}As multiple quantum wells was investigated in the integer quantum Hall regime. The measurements have been performed in magnetic fields up to 14.5 T, at the temperature of 1.8 K. Experimental data indicate the discontinuous behavior of the magnetooptic Kerr effect spectrum as a function of the filling factor. For odd filling factor values ν=3 and 5 we observe the large spin splitting. The effects cannot be explained in the one-particle model.

2

Faraday Rotation in Multiple Quantum Wells of GaAs/AlGaAs

100%

Dudziak E., Bożym J., Pruchnik D., Wasilewski Z.

Acta Physica Polonica A

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1996

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vol. 90

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issue 5

1022-1026

EN

We report on the results of first measurements of the Faraday rotation of modulated n-doped multiple quantum wells of GaAs/Al_{x}Ga_{1-x}As (x = 0.312). The measurements have been performed in the magnetic fields up to 13 T at the temperature of 2 K, in the spectral region of interband transitions. A rich structure of magneto-excitons has been found in the measured spectra. Faraday rotation (phase) measurements are proposed as an alternative method to photoluminescence excitation for investigations of magneto-excitons in quantum wells. The dependence of the measured Faraday rotation on magnetic field and hypothetical connections with quantum Hall effect are also discussed.

3

Dynamics of Excitation Transfer Inside InAs/GaAs Quantum Dot System

100%

Korona K., Babiński A., Raymond S., Wasilewski Z.

Acta Physica Polonica A

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2006

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vol. 110

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issue 2

219-224

EN

We present time-resolved photoluminescence investigations of InAs/GaAs structures containing quantum dots with the ground state at 1.43 eV. State filling effect and a Pauli blocking effect were clearly observed. These effects significantly influenced dynamics of excitation transfer from upper to lower state inside a dot leading to non-exponential dynamics. Numerical model based on nonlinear rate equations was proposed. The model described well the experimental data providing values of: lifetime of the ground state 0.53±0.03 ns, lifetime of excited state (when the ground state is full) 1.1±0.2 ns, and internal relaxation time (when the ground state is empty) 0.07±0.01 ns.

4

Localization of Excitons in the Wetting Layer Accompanying Self-Assembled InAs/GaAs Quantum Dots

88%

Babinski A., Raymond S., Wasilewski Z., Lapointe J., Potemski A.

Acta Physica Polonica A

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2004

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vol. 105

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issue 6

547-552

EN

A wetting layer is a narrow, highly strained quantum well, which accompanies quantum dots grown in Stranski-Krastanow mode. Its importance for a full description of the quantum dots properties has recently been pointed out. It has been shown for example that excitons can be localized by potential fluctuations in the wetting layer. This is equivalent to the formation of "natural" quantum dots in the WL. Excitonic emission from the single dots formed in the wetting layer accompanying the InAs/GaAs self-assembled quantum dots has been investigated in a high magnetic field (up to 23 T). Quadruplet splitting of the investigated emission line has been observed. The attribution of the emission line to the recombination of negatively charged exciton is discussed.

5

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

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2011

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vol. 119

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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

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

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2012

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vol. 122

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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

Neutral and Charged Excitons Localized in the InAs/GaAs Wetting Layer

64%

Babiński A., Czyż M., Golnik A., Borysiuk J., Kret S., Raymond S., Lapointe J., Wasilewski Z.

Acta Physica Polonica A

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2008

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vol. 114

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issue 5

1055-1060

EN

It has recently been shown that potential fluctuations in a wetting layer, which accompanies InAs/GaAs quantum dots can localize excitons. Neutral excitons and biexcitons and charged excitons were identified. In this communication we report on studies of properties of the excitons over wide temperature range (T < 70 K). The micro-photoluminescence measurements enable investigation of excitons localized in a single potential fluctuation. Temperature-induced broadening of the neutral exciton as well as a quenching of the charged exciton at temperatures higher than 50 K are observed and discussed.

8

Breakdown of the Quantum Hall Effect

64%

Maude D., Rigal L., Desrat W., Potemski M., Portal J., Eaves L., Wasilewski Z., Toropov A., Hill G.

Acta Physica Polonica A

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2001

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vol. 100

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issue 2

213-226

EN

The breakdown of the dissipationless conductance in the integer and fractional quantum Hall effect regime is reviewed. The temperature dependence of the critical current and of the critical magnetic field at breakdown bears a striking resemblance to the phase diagram of the phenomenological two-fluid Gorter-Casimir model for superconductivity. In addition, a remarkably simple scaling law exists between different filling factors.

9

Terahertz Detection of Quantum Cascade Laser Emission by Plasma Waves in Field Effect Transistors

52%

Teppe F., Consejo C., Torres J., Chenaud B., Solignac P., Fathololoumi S., Wasilewski Z., Zholudev M., Dyakonova N., Coquillat D., El Fatimy A., Buzatu P., Chaubet C., Knap W.

Acta Physica Polonica A

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2011

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vol. 120

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issue 5

930-932

EN

We report on the resonant detection of a 3.1 THz radiation produced by a quantum cascade laser using a 250 nm gate length GaAs/AlGaAs field effect transistor at liquid nitrogen temperature. We show that the physical mechanism of the detection is related to the plasma waves excited in the transistor channel. The detection is enhanced by increasing the drain current and driving the transistor into saturation regime. These results clearly show that plasma wave nanometer-size transistors can be used as detectors in all-solid-state terahertz systems where quantum cascade lasers act as sources.

10

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

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2013

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vol. 124

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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.

Refine search results

Large Filling-Factor-Dependent Spin Splitting in Magnetooptic Kerr Effect in GaAs/AlGaAs Multiple Quantum Wells

Faraday Rotation in Multiple Quantum Wells of GaAs/AlGaAs

Dynamics of Excitation Transfer Inside InAs/GaAs Quantum Dot System

Localization of Excitons in the Wetting Layer Accompanying Self-Assembled InAs/GaAs Quantum Dots

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

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

Neutral and Charged Excitons Localized in the InAs/GaAs Wetting Layer

Breakdown of the Quantum Hall Effect

Terahertz Detection of Quantum Cascade Laser Emission by Plasma Waves in Field Effect Transistors

Properties of Excitons in Quantum Dots with a Weak Confinement