ACTA

Optical Orientation of Trions in Charge-Tunable InAs/GaAs Quantum Dots

S. Laurent^a, B. Eble^a, O. Krebs^a, A. Lemaître^a, B. Urbaszek^b, X. Marie^b, T. Amand^b and P. Voisin^a
^aLaboratoire de Photonique et Nanostructures-CNRS Route de Nozay, 91460 Marcoussis, France
^bLaboratoire de Magnétisme, Nanophysique et Optoélectronique, INSA 135 Avenue de Rangueil, 31077 Toulouse Cedex, France

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We report on optical orientation of excitons and trions (singly charged exciton) in individual charge-tunable self-assembled InAs/GaAs quantum dots. When the number of electrons varies from 0 to 2, the trion photoluminescence under quasi-resonant excitation gets progressively polarized from zero to ≈ 100%. We discuss this behavior as the e±cient quenching of exciton spin quantum beats in anisotropic quantum dots due to the trion formation. This result indicates a long hole-spin relaxation time larger than the radiative lifetime, confirmed by time-resolved photoluminescence measurements carried out on a quantum dots ensemble.

DOI: 10.12693/APhysPolA.106.185
PACS numbers: 71.70.-d, 72.25.Fe, 73.21.La, 78.47.+p