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HL: Fachverband Halbleiterphysik
HL 32: Quantum dots and wires: preparation and characterization I
HL 32.7: Talk
Wednesday, February 27, 2008, 15:45–16:00, ER 270
Low strain AlGaInAs Quantum Dots for Cavity Quantum Electrodynamic Experiments — •Christian Schneider, Andreas Loeffler, Stephan Reitzenstein, Sven Hoefling, and Alfred Forchel — Universitaet Wuerzburg, Germany
We present a novel kind of quantum dots (QDs) suitable for short-wavelength cavity QED (quantum electrodynamics) applications in the GaAs material system. Using the ability of the AlGaInAs material system to tailor the QD morphology and emission wavelength independently, we realized QDs with enlarged dimensions emitting below 900 nm by solid source MBE growth. Despite adding low amounts of aluminum into the QDs, the QD density could be reduced to 3*10 9cm−2 by enhancing the surface diffusion length of the deposited atoms. The QDs showed elongations along the [0-11] direction of more than 100 nm, widths of 40 nm and heights of less than 5 nm. Low temperature photoluminescence measurements revealed that the QDs emit below 900 nm with an inhomogeneous broadening of 45 meV. Tuning low density QD arrays with enlarged dimension into the emission range below 900 nm, where highly sensible streak cameras and Si APDs have increased efficiencies, makes them promising candidates for cavity QED experiments. In a first approach we embedded a single QD layer in an AlAs/GaAs micropillar cavity with quality factors exceeding 50000 for a 4 µm pillar. By temperature tuning a single QD in resonance with the fundamental mode of the cavity we could measure a clear enhancement of the spontaneous emission rate in a micro PL study.