Regensburg 2007 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 25: Quantum dots and wires: Optical properties II
HL 25.7: Vortrag
Dienstag, 27. März 2007, 15:45–16:00, H17
Influence of In0.15Ga0.85As capping layers on the valence and conduction band structure of InAs quantum dots — •Mirja Richter1,2, Dirk Reuter1, Jean-Yves Duboz2, and Andreas D. Wieck1 — 1Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum — 2Centre de Recherche sur l’Hétéro-Epitaxie et ses Applications, CNRS, Sophia-Antipolis, F-06560 Valbonne
We have prepared self-assembled InAs quantum dots (QDs) capped by GaAs and In0.15Ga0.85As, respectively, by molecular beam epitaxy. The In0.15Ga0.85As cap layer shifts the ground state photoluminescence (PL) emission from 1261 nm to 1319 nm, which might be useful for telecommunication purposes. The QDs were embedded into n- or p-type capacitance-voltage (C(V)) structures to investigate the conduction and valance band states, respectively. The red-shift of the interband transitions due to the In0.15Ga0.85As layer observed in PL is compared to the shift of the corresponding energy levels obtained from C(V) measurements. The shifts of the ground states obtained from C(V) spectroscopy sum up to 42 meV, which is in good agreement with 43 meV observed in PL measurements. A small difference could be caused by a change in the exciton binding energy. From the 42 meV overall red-shift, 83 % originate from the conduction and only 17 % from the valence band. This is probably due to the smaller effective mass in the conduction band, so that here changes in the confinement potential result in larger changes in the energy levels.