Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 44: Poster Session: Quantum Dots and Wires - Transport & Optical Properties
HL 44.21: Poster
Dienstag, 27. März 2012, 09:30–12:30, Poster D
Optical Transitions in Si-Ge-Heterostructures — •Petru Tighineanu1, Inga Anita Fischer2, Jörg Schulze2, and Kurt Busch3 — 1Institut für Theoretische Festkörperphysik, Karlsruhe Institut für Technologie, Karlsruhe, Germany — 2Institut für Halbleitertechnik, Universität Stuttgart, Stuttgart, Germany — 3Institut für Physik, Humboldt-Universität zu Berlin, Berlin, Germany
We investigate optical transitions in low-dimensional Si-Ge-heterostructures such as Ge dots embedded in a Si matrix. The MBE growth of Ge dots on prepatterned Si substrates affords a high degree of control over dot geometry, size homogeneity, and dot positions. Si-Ge intermixing during dot growth can be influenced by the choice of growth temperature. We present results on theoretical predictions for optical transition energies and charge distribution as a function of dot geometry and material composition using a multiband k.p envelope function formalism by taking into account the strain field and spin-orbit coupling. In particular, we show that spatial inhomogeneities in the Ge content of the dot can lead to increased quantum confinement and, therefore, to an effective reduction in dot size. We compare our model predictions with measurements with a view towards functionalizing the structures for Si-Ge optoelectronic applications.