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

100%

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

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.

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

84%

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

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.

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

84%

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

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.

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3 Acta Physica Polonica A

1 2008

1 2005

1 1998

3 Astakhov G.

3 Ossau W.

1 Bass U.

1 Brunner K.

1 Forchel A.

1 Geurts J.

1 Heinrich J.

1 Höfling S.

1 Karczewski G.

1 Kiessling T.

1 Kochereshko V.

1 Kosobukin V.

1 Kossut J.

1 Landwehr G.

1 Mahapatra S.

1 Molenkamp L.

1 Quast J.

1 Schumacher C.

1 Wojtowicz T.

1 Yakovlev D.

Search results

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

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

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