Eight-band k⋅p calculations of the composition contrast effect on the linear polarization properties of columnar quantum dots

Abstract

Access to the full text of the published version may require a subscription. We present eight-band k · p calculations of the electronic and polarization properties of columnar In z Ga 1−z As quantum dots ͑CQD͒ with high aspect ratio embedded in an In x Ga 1−x As/ GaAs quantum well. Our model accounts for the linear strain effects, linear piezoelectricity, and spin-orbit interaction. We calculate the relative intensities of transverse-magnetic ͑TM͒ and transverse-electric ͑TE͒ linear polarized light emitted from the edge of the semiconductor wafer as a function of the two main factors affecting the heavy hole-light hole valence band mixing and hence, the polarization dependent selection rules for the optical transitions, namely, ͑i͒ the composition contrast z / x between the dot material and the surrounding well and ͑ii͒ the dot aspect ratio. The numerical results show that the former is the main driving parameter for tuning the polarization properties. This is explained by analyzing the biaxial strain in the CQD, based on which it is possible to predict the TM to TE intensity ratio. The conclusions are supported by analytical considerations of the strain in the dots. Finally, we present the compositional and geometrical conditions to achieve polarization independent emission from InGaAs/GaAs CQDs. Rights

Phonon-assisted radiative recombination of excitons confined in strongly anisotropic nanostructures

“…The parameters l y , l z , l x are related to the QDash width D, height H , and length L. In order to get a better insight how the model parameters scale up with the real physical QDash dimensions and for the sake of comparison with the experiment, values for l y , l z , and l x are taken from more realistic wave function calculations using an eight-band k · p model [44,45] and fitting the obtained electron and heavy-hole ground state probability densities with the density corresponding to the wave function from Eq. (1).…”

Exciton spin relaxation in InAs/InGaAlAs/InP(001) quantum dashes emitting near 1.55μm

“…Based on the preliminary discussion of excitonic states, polarization injection might be expected to be equally effective for V and H cases as interband dipole moments of the two bright states are collinear with respective axes. The interband contribution to the dipole moment is commonly regarded as dominant, 22 however, the usually neglected intraband term may become substantial for structures of a large volume. The macroscopic character of this contribution (d intra / hw e jrjw h i, where jw e=h i are the e/h envelope functions), in combination with a significant elongation of QDashes, promotes the V component of d intra approximately to the same extent for both bright states.…”

Single photon emission up to liquid nitrogen temperature from charged excitons confined in GaAs-based epitaxial nanostructures

“…The unique structure of CQDs makes it possible to tailor the built-in strain field and the quantum confinement. 23,24 This in turn can allow manipulating the emitter properties via intentionally forming the light-hole exciton, for instance, enabling the control of the polarization properties, 25,26 engineer the exciton dipole moment 25 crucial for optical Stark effect tuning, 27 or it could lead to the reduction of the exciton fine structure splitting. 28 Consequently, it may be possible to consider a CQD structure not only as a well-controlled single photon emitter with broad range of tunable parameters but also as a potential source of polarization-entangled photon pairs.…”