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HL: Halbleiterphysik

HL 56: Quantum dots and wires: Preparation and characterization III

HL 56.2: Vortrag

Freitag, 31. März 2006, 11:15–11:30, POT 51

Strain-enhanced charge carrier confinement in nanostructures fabricated by cleaved edge overgrowth — •Jörg Ehehalt¹, Robert Schuster¹, Christian Gerl¹, Harald Hajak¹, Elisabeth Reinwald¹, Matthias Reinwald¹, Dieter Schuh¹, Werner Wegscheider¹, Max Bichler², and Gerhard Abstreiter² — ¹Universität Regensburg — ²Walter-Schottky-Institut TU München

The Cleaved Edge Overgrowth technique was used to fabricate quantum wires and quantum dot systems with precisely controlled sizes and positions. Conventionally two intersecting GaAs quantum wells lead to the formation of a quantum wire at the T-shaped junction with confinement energies of up to 54 meV.

However, a larger confinement is needed in order to examine excited states and observe quantum effects at higher temperatures. This can be achieved by introducing tensile strain between materials with different lattice constants. Micro-photoluminescence spectroscopy of purely strain-induced quantum wires shows confinement energies of up to 52 meV. By combining conventional T-shaped wires with strain-induced confinement, much larger confinement energies are possible. Simulations predict confinement energies of up to 108 meV.

These results are now to be applied to fabricate quantum wire lasers working at higher temperatures and lower threshold currents as well as quantum dot system, which will be used to study generation, detection and lifetimes of spin-polarized charges.