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

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 View the MathML source. A zero field polarization of the heavy-hole excitons is found, which compensates at View the MathML source. 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.