Dresden 2011 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 71: Quantum Dots: Optical Properties
HL 71.2: Vortrag
Donnerstag, 17. März 2011, 10:30–10:45, POT 251
Dynamic control of charge carrier injection into individual quantum dots and quantum posts by surface acoustic waves — •Florian J. R. Schülein1, Stefan Völk1, Florian Knall1, Dirk Reuter2, Andreas D. Wieck2, Tuan A. Truong3, Heejung Kim3, Pierre M. Petroff3, Achim Wixforth1, and Hubert J. Krenner1 — 1Lehrstuhl für Experimentalphysik I, 86159 Augsburg, Germany — 2Lehrstuhl für Angewandte Festkörperphysik, 44780 Bochum, Germany — 3Materials Department, University of California, Santa Barbara, CA 93106, United States
We present a detailed study of the surface acoustic wave (SAW) power dependence on the carrier injection into and recombination in self-assembled quantum posts (QPs) and quantum dots (QDs). The matrix quantum well of QPs is a wide (∼23nm) confinement potential, in contrast to the wetting layer of QDs. Thus, the energy levels of the thin (∼ 1−2nm) wetting layer is modulated by monolayer fluctuations giving rise to charge carrier traps and very low overall mobility. For both systems we observe a clear switching between different states (X0 and X+/−) with increasing SAW power. This switching is symmetric in SAW power for QPs and shows a broad hysteresis for QDs. This can be explained by SAW driven ionization of traps within the wetting layer during the up-sweep of the SAW power. With a laser excitation scheme for which the phase of the SAW is locked to the excitation laser, we are able to resolve the full phase information of this dynamically driven carrier injection.