Dresden 2011 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 63: II-VI-Compounds
HL 63.1: Talk
Wednesday, March 16, 2011, 15:45–16:00, POT 151
Band gap bowing of binary alloys: Experimental results compared to theoretical tight-binding supercell calculations for CdxZn1−xSe — •Daniel Mourad1, Gerd Czycholl1, Carsten Kruse2, Sebastian Klembt2, Reiner Retzlaff2, Detlef Hommel2, Mariuca Gartner3, and Mihai Anastasescu3 — 1Institut für Theoretische Physik, Universität Bremen — 2Institut für Festkörperphysik, Universität Bremen — 3Institute für Physikalische Chemie "Ilie Murgulescu", Rumänische Akademie
Compound semiconductor alloys of the type AxB1−xC find widespread applications as their electronic bulk band gap varies continuously with x, and therefore a tayloring of the energy gap is possible by variation of the concentration. We model the electronic properties of such semiconductor alloys by a multiband sp3 tight-binding model on a finite ensemble of supercells and determine the band gap of the alloy. This treatment allows for an intrinsic reproduction of band bowing effects as a function of the concentration x and is exact in the alloy-induced disorder. In the present talk, we concentrate on bulk CdxZn1−xSe as a well-defined model system and give a careful analysis on the proper choice of the basis set and supercell size, as well as on the necessary number of realizations. The results are compared to experimental results obtained from ellipsometric measurements of CdxZn1−xSe layers prepared by molecular beam epitaxy (MBE) and photoluminescence (PL) measurements on CdxZn1−xSe nanowires reported in the literature.