Dresden 2011 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 44: Poster Session I
HL 44.50: Poster
Dienstag, 15. März 2011, 18:00–21:00, P3
Band Anticrossing in ZnSexTe1−x and ZnSxTe1−x Alloys — Tobias Bertram1, •Christian Karcher1, 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
The goal of this research is to understand the band forming in ZnSeTe and ZnSTe semiconductors. The Band Anticrossing Model (BAC) was already succesfully applied to explain the band formation in GaNAs. One can compare the chemical properties of ZnSeTe and ZnSTe with those of GaNAs. The key difference being while the electronegativity of Nitrate is almost double that of Arsenic, Tellurium’s is only slightly smaller than that of Selenium or Sulphur. Similar to GaNAs the localized Se and S states lie above the ZnTe conduction band. The BAC predicts a repulsion of the localized impurity states and the ZnTe conduction band, causing it to split into a so-called E−- and E+-band. The higher Se or S contents in the ZnTe host, the stronger the repulsion of the E−-band, leading to a shrinking of the bandgap energy. This behaviour can also be fitted by introducing a bowing parameter into the Virtual Crystal Approximation. ZnTe incorporated with varying contents of Se and S is characterized by various optical methods. Photoluminescence, photoreflectance and absorption spectroscopy measurements are used to fully determine both the emission and absorption characteristics of the system and by that help to gain further insight into the way the bands are formed.