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1

Carriers Diffusion in GaAs/AlAs Type II Quantum Well

100%

Lesiak A., Chwalisz B., Wysmołek A., Potemski M., Stępniewski R., Thierry-Mieg V.

Acta Physica Polonica A

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2005

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vol. 108

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issue 5

755-760

EN

The micro-photoluminescence of GaAs/AlAs type II double quantum well structure is presented. The specific band alignment of the investigated system allows obtaining high concentration of long lived carriers. This enables us to study diffusion of carriers and/or indirect excitons. It was found that the carrier flow does not follow the classical diffusion equation and is driven by the potential modification due to the presence of photo created carriers.

2

Emission from Mesoscopic-Size Islands Formed in a GaAs/AlAs Double Layer Structure

100%

Wysmołek A., Chwalisz B., Potemski M., Stępniewski R., Babiński A., Raymond S., Thierry-Mieg V.

Acta Physica Polonica A

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2004

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vol. 106

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issue 3

367-381

EN

The nature of sharp emission lines which are present in macro-luminescence experiments on a type-II GaAs/AlAs double quantum well structure is discussed. The experiments, which also include micro-lumines- cence measurements, allowed us to conclude that the sharp emission lines observed originate from lateral GaAlAs islands of a fewμm in diameter. They serve as efficient type-I recombination centers for indirect excitons and/or carriers which diffuse in the GaAs/AlAs QW structure and strongly affect the emission processes observed in macro-luminescence experiments. These traps can easily be filled with electron-hole pairs, giving rise to the formation of neutral excitons as well as more complex excitonic molecules. Magneto-luminescence spectra from single islands resemble those observed for natural quantum dots formed in narrow GaAs quantum wells.

3

Spatially Resolved Micro-Luminescence from GaN/AlGaN Quantum Dots

84%

Chwalisz B., Wysmołek A., Bożek R., Stępniewski R., Pakuła K., Kossacki P., Golnik A., Baranowski J.

Acta Physica Polonica A

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2004

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vol. 105

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issue 6

517-521

EN

We report on the optical experiments performed on low density GaN/AlGaN quantum dots grown on sapphire substrate using SiN during the growth process. The existence of quantum dots in the investigated structures was confirmed by atomic force microscopy. Although macro-luminescence of the investigated structures consist of broad emission lines the micro-photoluminescence experiments performed with the spatial resolution of 0.25 μm revealed sharp emission lines from the individual quantum dot in the energy range of 3.20-3.55 eV. It is shown that the magnetic fields up to 7 T do not influence significantly the electronic states of the dots.

4

Localization Effects in GaN/AlGaN Quantum Well - Photoluminescence Studies

68%

Chwalisz B., Wysmołek A., Bożek R., Korona K., Stępniewski R., Knap W., Pakuła K., Baranowski J., Grandjean N., Massies J., Prystawko P., Grzegory I.

Acta Physica Polonica A

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2003

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vol. 103

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issue 6

573-578

EN

Exciton localization in GaN/AlGaN quantum well structures is studied by photoluminescence. An anomalous temperature behavior of the photoluminescence from the quantum well is observed. With increasing temperature the energy position of the excitonic emission line first decreases up to 20 K, then increases, reaching a maximum around 90 K, and then decreases again in the higher temperature range. The observed behavior is discussed in terms of localization at the interface potential fluctuations. It is argued that the temperature activated migration and subsequent release of the excitons from traps that occurs between 20 K and 90 K are responsible for the observed S-like shape of the energy dependence. The obtained results allow a direct characterization of the energy fluctuations present in GaN/AlGaN quantum wells grown by different techniques.

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4 Acta Physica Polonica A

1 2005

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4 Chwalisz B.

4 Stępniewski R.

4 Wysmołek A.

2 Baranowski J.

2 Bożek R.

2 Pakuła K.

2 Potemski M.

2 Thierry-Mieg V.

1 Babiński A.

1 Golnik A.

1 Grandjean N.

1 Grzegory I.

1 Knap W.

1 Korona K.

1 Kossacki P.

1 Lesiak A.

1 Massies J.

1 Prystawko P.

1 Raymond S.

Carriers Diffusion in GaAs/AlAs Type II Quantum Well

Emission from Mesoscopic-Size Islands Formed in a GaAs/AlAs Double Layer Structure

Spatially Resolved Micro-Luminescence from GaN/AlGaN Quantum Dots

Localization Effects in GaN/AlGaN Quantum Well - Photoluminescence Studies