Regensburg 2007 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 48: Quantum dots and wires: preparation and characterization II

HL 48.6: Vortrag

Donnerstag, 29. März 2007, 17:30–17:45, H13

Advances in Quantum Dot Fabrication by Cleaved Edge Overgrowth — •Jörg Ehehalt, Christoph Kamseder, Christian Neugirg, Christian Gerl, Dieter Schuh, and Werner Wegscheider — Universität Regensburg, Germany

Single and coupled quantum dot systems with precisely controlled sizes and positions can be fabricated using the Cleaved Edge Overgrowth (CEO) method. They result from quantum mechanical bound states at the intersection of three perpendicular GaAs quantum wells.

Due to the high degree of growth control, these quantum dots are promising candidates for research in areas like quantum computing or photon correlation. However, most applications have been prevented so far by the relatively low confinement energies in these quantum dots of up to 10 meV. This value needs to be significantly increased in order to study excited states, apply external fields without loosing confinement and increase storage times of charge carriers.

Using techniques formerly applied to CEO-grown quantum wires, such as asymmetrical structures and strained layers, the confinement energies can be substantially improved. The properties of these structures are studied by photoluminescence and photoluminescence excitation spectroscopy and compared to theoretical simulations.

These structures are now to be used to generate and detect spin-polarized charges in the quantum dots and study the properties of quantum dot molecules made by arrays of quantum dots. The results can also be applied to fabricate novel quantum wire lasers working at higher temperatures and lower threshold currents.