Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 9: Poster I
HL 9.44: Poster
Montag, 27. März 2006, 15:15–17:45, P3
Phonon properties in Zn1−xMnxSe bulk epilayers and thickness effect on the shape of reststrahlen band — •K. C. Agarwal, B. Daniel, D. Kälblein, C. Klingshirn, and M. Hetterich — Institut für Angewandte Physik and Center for Functional Nanostructures (CFN), Universität Karlsruhe, D-76131 Karlsruhe, Germany
Recently, diluted magnetic semiconducts (DMS) like Zn1−xMnxSe attract a lot of attention due to their potential for the realization of spin devices. In this contribution, we present the results of our temperature dependent far infrared (FIR) investigations performed on MBE grown Zn1−xMnxSe epilayers. Our results reveal the phonon properties of this mixed crystal alloy. For the Zn1−xMnxSe samples with low Mn contents (x = 0, 8 %), the anharmonic interactions are small resulting in equal values of the transverse optical (TO)- and longitudinal optical (LO)-broadenings (γ). However, for the samples with larger Mn contents a significant difference between LO and TO broadenings is found. In addition to the known ZnSe-like and MnSe-like phonon resonances, we observe a weak feature below the MnSe-like phonon band. The frequency of this feature shows a temperature and Mn dependent shift. We suggest that this feature observed in our measurements is a “weak-mode”, which has its origin in the disorder resulting from the Mn incorporation in the samples. Additionally, the shape of the reststrahlen band is found to change significantly with layer thickness. This effect is studied in some detail for pure ZnSe epilayers by comparing our experimental data with theoretical simulations.