Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 3: Heterostructures

HL 3.7: Talk

Monday, March 23, 2009, 12:00–12:15, BEY 154

Internal quantum confined Stark effect in embedded IV-VI semiconductor nanodots — •Roman Leitsmann¹, Frank Ortmann¹, Friedhelm Bechstedt¹, Wolfgang Heiss², and Friedrich Schäffler² — ¹European Theoretical Spectroscopy Facility (ETSF) and Institut für Festkörpertheorie und -optik, Friedrich-Schiller Universität Jena, Germany — ²Institut für Halbleiter- und Festkörperphysik, Johannes-Kepler-Universität Linz, Austria

The characterization of nanostructure properties versus dimension is of increasing importance for the nanotechnology. Especially the stoichiometry, geometry, and the electronic states of IV-VI semiconductor nanodots are of special interest [1,2]. We use ab initio methods to calculate structural and electronic properties of PbTe nanodots embedded in a CdTe semiconductor matrix as a function of the dot diameter. The arrangement of polar dot-matrix interfaces induces an electrostatic field, which strongly influences the geometric and electronic properties and reduces the symmetry of the system. In particular, the localization of HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) states at opposite nanodot corners can be explained by an internal quantum confined Stark effect (IQCSE) [3]. Using a parabolic model potential for the electron and hole confinement it can be shown that the IQCSE lead to a strong reduction of the integrated photoluminescence yield at low temperatures.

[1] New J. Phys. 8, 317 (2006) [2] JACS 128, 3516 (2006); JACS 129, 11354 (2007) [3] Phys. Rev. B 78, 205324 (2008)