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HL: Halbleiterphysik
HL 25: Quantenpunkte (optische Eigenschaften)
HL 25.9: Vortrag
Mittwoch, 29. März 2000, 18:00–18:15, H15
Excitons, Biexcitons, and Dephasing in GaAs T-shaped quantum wires — •Wolfgang Langbein1, Hannes Gislason2, and Jørn M. Hvam3 — 1Lehrstuhl für Experimentelle Physik EIIb, Universität Dortmund, 44227 Dortmund — 2Farœse Telecom, P.O. Box 27, FO-110 Torshavn, Farœ islands. — 3Research Center COM, DTU Bldg. 349, 2800 Lyngby, Denmark
The binding energy of excitons and biexcitons and the exciton dephasing in T-shaped GaAs quantum wires is investigated by transient four-wave mixing. The T-shaped structure is fabricated by cleaved-edge overgrowth and its geometry is engineered to optimize the one-dimensional confinement. In this wire of 6.6×24 nm2 size we find a one-dimensional confinement of more than 20 meV, and an inhomogeneous broadening of only 3.4 meV. The measured exciton binding energy of 12 meV is in good agreement with numerical calculations. The biexciton binding energy of 2.0 meV is less than in comparable quantum well structures due to the different confinement of electron and hole in the T-shaped wire. A dispersion of the homogeneous linewidth within the inhomogeneous broadening due to phonon-assisted relaxation is observed. An exciton acoustic-phonon scattering coefficient of 6.1±0.5 µeV/K is found, which is larger than in comparable quantum-well structures.