Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

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

HL 56.6: Vortrag

Freitag, 31. März 2006, 12:15–12:30, POT 51

Influence of Indium-free sublayers on the formation of self-assembled quantum dots on InP (001) substrates — •Roland Enzmann, Susanne Dachs, Ralf Meyer, and Markus-Christian Amann — Walter Schottky Institut, Am Coulombwall 3, 85748 Garching

The deposition of InAs quantum dots on a lattice-matched AlGaInAs matrix material on (001) InP substrate leads to a prolate configuration known as "quantum dashes" oriented along the [1-10] direction. This effect is possibly caused by the indium atoms located in the uppermost layer of the matrix material of which the quantum dots are deposited. This layer is in the following called sublayer. To avoid this direction-dependent growth we investigate the influence of indium-free sublayers to grow self-assembled quantum dots on InP (001) substrates. To this end, we first prepared InAs quantum dots on a GaAs sublayer with 0,55nm thickness. In this way a reduction of the asymmetry has already been obtained. Since indium is known to segregate, thicker indium free sublayers might be instrumental to avoid "quantum dashes". Because of the heavy strain, a GaAs sublayer has to be very thin. Thicker sublayers can be achieved by the substitution of GaAs by GaAsSb, which principally can be grown lattice matched to InP. Accordingly, a further reduction of the asymmetry can be expected for InAs-GaAsSb-AlGaInAs quantum dots.