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4 Acta Physica Polonica A

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Optical Study of ZnTe-Based 2D and 0D Photonic Structures Containing CdTe/ZnTe Quantum Dots

100%

Jakubczyk T. , Kazimierczuk T. , Golnik A. , Bienias P. , Pacuski W. , Kruse C. , Hommel D. , Kłopotowski Ł. , Wojtowicz T. , Gaj J.

Acta Physica Polonica A

2009

tom 116

nr 5

888-889

We report on an optical study of ZnTe-based microcavity and micropillars. Angle-resolved reflectivity studies confirm a high quality of the investigated structure by setting the lower bound on the quality factor Q ≥ 1000, determined from normal-incidence reflection spectra. In a microphotoluminescence study, micropillar modes are observed at temperatures of the order of tens of kelvins. For structures grown by a complex growth procedure at two different MBE facilities, an enhancement of photoluminescence in the cavity mode is observed.

Deep Levels Induced by CdTe/ZnTe Quantum Dots

100%

Zielony E. , Placzek-Popko E. , Roznicka A. , Gumienny Z. , Szatkowski J. , Dyba P. , Pacuski W. , Kruse C. , Hommel D. , Guziewicz M.

nr 5

630-632

The electrical properties of the CdTe/ZnTe quantum dot system have been analyzed to identify deep-level defects related with the presence of quantum dots. The capacitance-voltage (C-V) and deep level transient spectroscopy measurements were used to investigate the samples. A reference ZnTe sample (without dots) was also studied for comparison. Both samples were grown by molecular beam epitaxy technique on the n-type GaAs substrate. The quantum dots were formed by a Zn-induced reorganization of a thin CdTe layer. The presence of quantum dot formation was confirmed by micro-photoluminescence measurements. The deep level transient spectra for both samples are complex. In order to characterize individual contributions to the deep level transient spectra the latter have been simulated by separated Gaussian components [1]. The results of the deep level transient spectroscopy measurements yield the conclusion that the same defects are present in both materials but there is an increased concentration of the defects in the quantum dot structures. No deep level associated directly with the quantum dot confinement has been identified.

Optical Properties of CdTe QDs Formed Using Zn Induced Reorganization

100%

Kobak J. , Pacuski W. , Jakubczyk T. , Kazimierczuk T. , Golnik A. , Frank K. , Rosenauer A. , Kruse C. , Hommel D. , Gaj J.

nr 5

627-629

In this paper we present optical studies of CdTe quantum dots formed using Zn-induced reorganization. The pattern of quantum dot photoluminescence lines is found to be similar to typical results reported for quantum dots grown with other techniques, although the positively charged exciton line is relatively more pronounced. Also the energy spacing between biexciton and exciton lines is found to be larger than in typical results. Zn-induced reorganization results in quantum dots density higher by an order of magnitude than in Te-induced quantum dots.

Relationship between Sample Morphology and Carrier Diffusion Length in GaN Thin Films

80%

Godlewski M. , Goldys E. , Phillips M. , Böttcher T. , Figge S. , Hommel D. , Czernecki R. , Prystawko P. , Leszczynski M. , Perlin P. , Wisniewski P. , Suski T. , Bockowski M. , Grzegory I. , Porowski S.

nr 4-5

627-632

Scanning and spot-mode cathodoluminescence investigations of homo- and hetero-epitaxial GaN films indicate a surprisingly small influence of their microstructure on overall intensity of a light emission. This we explain by a correlation between structural quality of these films and diffusion length of free carriers and excitons. Diffusion length increases with improving structural quality of the samples, which, in turn, enhances the rate of nonradiative recombination on structural defects, such as dislocations.