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HL: Fachverband Halbleiterphysik

HL 31: Poster II

HL 31.49: Poster

Dienstag, 26. Februar 2008, 16:30–19:00, Poster D

Enhanced charge carrier confinement in quantum dots and wires fabricated by cleaved edge overgrowth — •Jörg Ehehalt, Christian Neugirg, Dieter Schuh, and Werner Wegscheider — Universität Regensburg, Germany

The Cleaved Edge Overgrowth technique (CEO) is used to fabricate quantum wires and dots with precisely controlled sizes and positions. These structures are formed by quantum mechanical bound states at the intersection of two or three perpendicular quantum wells.

Confinement energies of up to 54 meV for wires and 10 meV for dots have been reported. However, a larger confinement is needed in oder to study excited states, apply external fields without loosing confinement and for application in room-temperature devices. This can be achieved by asymmetric intersections and tensile strain between materials with different lattice constants.

Using a combination of these techniques, the confinement energy can be significantly improved. The properties of these nanostructures are studied by photoluminescence and photoluminescence excitation spectroscopy and the results compared to theoretical simulations.

These results are also applied to fabricate novel electrically-pumped quantum wire lasers operating at higher temperatures and lower threshold currents. In addition, single and coupled CEO quantum dots with higher confinement energies are promising candidates for research in areas like quantum information processing.