Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 92: Poster Session: II-VI Semiconductors & ZnO and related Materials

HL 92.1: Poster

Donnerstag, 29. März 2012, 16:00–19:00, Poster D

Optical spectroscopy of MBE grown ZnSe_xTe_1−x and ZnS_xTe_1−x layers — •Tobias Bertram¹, Christian Karcher¹, Carsten Kruska¹, Henning Klaer², Sebastian Klembt², Carsten Kruse², Detlef Hommel², and Wolfram Heimbrodt¹ — ¹Department of Physics and Material Sciences Centre, Philipps University of Marburg, Germany — ²Institute of Solid State Physics, University of Bremen, Germany

This study aims to produce a comprehensive understanding of the band formation processes in ZnSe_xTe_1−x and ZnS_xTe_1−x semiconductor alloys. These solid solutions are known to feature large bowing parameters which cannot be explained solely by disorder as demonstrated in other II-VI systems, e.g. ZnSe_xS_1−x. This behaviour has previously been observed in II(N, VI) alloys, where it stemmed from the high differences in electronegativity and size between the substitutional N and the replaced ion. Such conditions create a strong interaction between the localized electronic states and the band structure of the host. This can be described by the band anticrossing (BAC) model, which results in a respective formation of two subbands E₋ and E₊. To evaluate the applicability of this model to mixed II-VI semiconductors, e.g. the case of Se or S impurities in the ZnTe host, high quality layers grown by molecular beam epitaxy were studied using photoluminescence, photo- and electromodulated reflectance and absorption spectroscopy. These measurements reveal the emission and absorption characteristics of the systems between room temperature and 10 K.

The relevance of the BAC model will be discussed in detail.