Anomalous anticrossing of neutral exciton states in GaAs/AlGaAs quantum dots

Abstract

International audienceWe study the effects of heavy hole-light hole (HH-LH) mixing on fine-structure and polarization properties of neutral excitons ( X-0) confined in single GaAs/AlGaAs quantum dots (QDs) under the application of anisotropic biaxial stress. In the large HH-LH mixing regime, these properties are substantially different from the usually observed properties in the case of small or no mixing. By varying the applied stress, the mixing in the initially strain-free QDs changes from similar to 0 to similar to 70% and an anomalous anticrossing of the X-0 bright states is observed. The latter is attributed to stress-induced rotation of the in-plane principal axis of the QD confinement potential. We show that the analysis of free-excitonic emission of bulk GaAs surrounding the QDs not only allows estimation of the stress and mixing in the QDs, but also provides the quantum-confinement-induced HH-LH splitting of the as-grown QDs

Flatland Nanophotonics: A Study of Quantum-Confined Excitons in 2D Materials

“…External perturbations like strain, electric field and magnetic field or sometimes a combination of different knobs are used to erase the FSS [130,131]. FSS is also observed for the case of the quantum emitters in WSe 2 .…”

Mechanically encoded single-photon sources: Stress-controlled excitonic fine structures of droplet epitaxial quantum dots

“…Figure 3 by Refs. [8,31,32]. Another obvious observation is that the optical polarization axes of the QD under the misaligned uniaxial stresses are no longer aligned to either the x-or the y-axes, but directed in between and accompanied with significant changes of the magnitudes of the FSS and DOP.…”

“…[31] To highlight the VBM effect, Fig. 2 (b) presents the emission spectra of the same stressed QD that are calculated regardless of the VBM (by artificially setting S k = S ǫ = 0 and…”

Advanced Technologies for Quantum Photonic Devices Based on Epitaxial Quantum Dots

“…demonstrated that, out of an InAs QD population that emitted with polarization preferentially aligned with the [1–10] GaAs crystal axis, 30% demonstrated the emission of polarization‐entangled photons upon application of strain parallel or perpendicular to [1–10] . Likewise, GaAs QDs have an anisotropy axis that is preferably aligned along the [110] crystal direction, however with considerably less variability than InAs dots—a favorable characteristic for obtaining large numbers of dots with negligible FSS …”