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Optical Properties of Diluted Magnetic Semiconductor Quantum Structures

100%

Dobrowolska M., Luo H., Furdyna J. K.

Conduction and valence band edges in diluted magnetic semiconductors undergo enormous Zeeman shifts when a magnetic field is applied, reaching values in excess of 100 meV at low temperatures. These Zeeman shifts can thus have profound consequences on the properties of DMS/non-DMS heterostructures, since they provide the opportunity of tuning their band alignment by varying an applied field. This leads to a variety of entirely new effects, and also provides a powerful tool for probing the effect of band alignment on the properties of semiconductor heterostructures in general. We illustrate this with several examples. First, using the ZnSe/ZnMnSe system, we discuss the creation of a spatial spin modulation (spin superlattice). Second, we use the drastic differences in the Zeeman splitting occurring in different layers of a DMS/non-DMS superlattice in order to pinpoint the localization in space of the specific electronic states involved in optical transitions. We illustrate this by investigating the localization of above-barrier states in type-I ZnSe/ZnMnSe superlattices, and of spatially-direct (type-I) excitons which occur in ZnTe/CdMnSe and ZnMnTe/CdSe type-II super-lattices. Finally, we exploit Zeeman tuning to demonstrate the confinement effects which occur in a single quantum barrier.

Investigation of Strain in II-VI Semiconductor Superlattices Using Electron Paramagnetic Resonance of Mn^{++}

76%

Furdyna J. K., Qazzaz M., Yang G., Montes L., Xin S. H., Luo H.

Acta Physica Polonica A

1995

vol. 88

issue 4

607-618

We explore the possibility of using electron paramagnetic resonance (EPR) of Mn^{++} for measuring uniaxial strain in II-VI superlattices. This work is motivated by the fact that the EPR spectrum of Mn^{++} is very strongly affected by crystalline fields. Changes in a crystalline field which arise from strain are thus automatically expected to have a profound effect on the EPR spectrum. Consistent with this expectation, we have observed giant crystal field splittings of Mn^{++} EPR lines in ZnTe/MnTe, CdTe/MnTe, and ZnTe/MnSe superlattices. The EPR spectra observed in these systems are ascribed to isolated Mn^{++} ions diffused into the ZnTe or the CdTe layers from the respective MnTe or MnSe layers. In addition to providing precise information oii the magnitude and the sign of strain produced by lattice mismatch between the superlattice constituents, we show that the EPR spectrum also provides a direct measure of strain fluctuations in the layered medium.

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2 Acta Physica Polonica A

2 1995

2 Furdyna J. K.

2 Luo H.

1 Dobrowolska M.

1 Montes L.

1 Qazzaz M.

1 Xin S. H.

1 Yang G.

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Optical Properties of Diluted Magnetic Semiconductor Quantum Structures

Investigation of Strain in II-VI Semiconductor Superlattices Using Electron Paramagnetic Resonance of Mn^{++}