Polarization-resolved electro-absorption in InAs/GaAs quantum dots in waveguide structures—modeling of size, shape and In-content

• Published in: Physica. E, Low-dimensional systems & nanostructures Vol. 17; pp. 554 - 556
• Main Authors: Wolst, Oliver, Kahl, Matthias, Schardt, Michael, Malzer, Stefan, Döhler, Gottfried H
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2003
• Subjects: Electro-absorption; Polarization; Self-assembled quantum dots; Polarization; Self-assembled quantum dots; Electro-absorption
• ISSN: 1386-9477; 1873-1759
• DOI: 10.1016/S1386-9477(02)00868-8

Integrating InAs self-assembled quantum dots into p–i–n (and n–i–p) waveguide structures allows for polarization resolved electro-absorption measurements of quantum dot single excitonic transitions. In this geometry, the field dependence of three electron heavy-hole and three electron light-hole transitions has been investigated. The light-hole ground state exciton is separated from the heavy-hole ground state transition by 160 meV . A zero field polarization of the heavy-hole excitons is found, which compensates at −75 kV/cm . The light hole excitons, however, do not indicate any dipole moment. In contrast to the heavy-hole transitions they show a strongly pronounced field dependence. Modeling these extensive results, the parameter space with respect to shape, size and In-content of the quantum dot turns out to be very narrow. As a key issue, the light-/heavy-hole splitting is strongly influenced by the biaxial strain, which in turn depends on the width/height ratio of the dot. The best agreement with the experimental data has been achieved by assuming a lens-shaped dot with a trumpet-shaped In-distribution.