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Coupling of Quantum Dots with Quantum Wells in a System Based on (Cd,Zn,Mg)Te

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Połczyńska K., Janik E., Kossacki P., Pacuski W.

Acta Physica Polonica A

2017

vol. 132

issue 2

369-371

Coupled low dimensional structures have potential applications in quantum computing and spintronics. Using molecular beam epitaxy we fabricated three kinds of systems of coupled quantum wells and quantum dots with different energy order: wells at higher energy than dots, resonant structures, and dots at higher energy than wells. By analysis of photoluminescence and reflectivity spectra, we conclude that there is a possibility of effective carrier tunneling between structures, which opens possibility of subsequent testing of spin transfer efficiency.

Optimizing the InGaAs/GaAs Quantum Dots for 1.3 μm Emission

100%

Maryński A., Mrowiński P., Ryczko K., Podemski P., Gawarecki K., Musiał A., Misiewicz J., Quandt D., Strittmatter A., Rodt S., Reitzenstein S., Sęk G.

Acta Physica Polonica A

2017

vol. 132

issue 2

386-390

Hereby we present comprehensive experimental and theoretical study on fundamental optical properties and electronic structure of GaAs-based quantum dots grown using metalorganic chemical vapor deposition technique. The substantial redshift of emission, to the second telecommunication window of 1.3 μm, in comparison to standard InGaAs/GaAs quantum dots is obtained via strain engineering utilizing additional capping layer of In_{0.2}Ga_{0.8}As in this context referred to as strain reducing layer. It ensures lowering of the energy of the ground state transition to more application relevant spectral range. Optical properties of the quantum dot structure has been experimentally characterized by means of photoreflectance spectroscopy and power-dependent photoluminescence revealing 3 transitions originating from hybrid states confined in an asymmetric double quantum well formed of the wetting layer and strain reducing layer, as well as higher states of the quantum dots themselves with the first excited state transition separated by 67 meV from the ground state transition. Origin of the observed transitions was confirmed in theoretical modelling using 1-band single-particle approach for the quantum well part, and excitonic quantum dot spectrum obtained within 8 band k·p formalism followed by configuration interaction calculations, respectively. Additionally, photoluminescence excitation spectroscopy measurements allowed to identify a spectral range for efficient quasi-resonant excitation of the investigated quantum dots into the 2D density of states to be in the range of 835-905 nm.

Photochromism and magneto-optic response of ZnO:Mn semiconductor quantum dots fabricated by microemulsion route

100%

Misra N., Roy M., Mohanta D., Baruah K., Choudhury A.

Open Physics

2008

vol. 6

issue 1

109-115

ZnO:Mn semiconductor quantum dots were prepared by solution casting led microemulsion route. Quantum dots of average size ∼2 nm were noticed in transmission electron micrographs. The present work highlights colour change phenomena (photochromic effect) of quantum dots while subjected to photon illumination. The magneto-optic measurements e.g. magnetic field (H) vs angle of rotation (θ) show step like behavior and is ascribed to the quantum confinement effect of diluted magnetic ZnO:Mn nanostructures. Further, underlying mechanism responsible for exhibiting photochromism and magneto-optic effects are also discussed.

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2 Acta Physica Polonica A

1 Open Physics

2 2017

1 2008

1 Baruah K.

1 Choudhury A.

1 Gawarecki K.

1 Janik E.

1 Kossacki P.

1 Maryński A.

1 Misiewicz J.

1 Misra N.

1 Mohanta D.

1 Mrowiński P.

1 Musiał A.

1 Pacuski W.

1 Podemski P.

1 Połczyńska K.

1 Quandt D.

1 Reitzenstein S.

1 Rodt S.

1 Roy M.

1 Ryczko K.

1 Strittmatter A.

1 Sęk G.

Search results

Coupling of Quantum Dots with Quantum Wells in a System Based on (Cd,Zn,Mg)Te

Optimizing the InGaAs/GaAs Quantum Dots for 1.3 μm Emission

Photochromism and magneto-optic response of ZnO:Mn semiconductor quantum dots fabricated by microemulsion route