Fine structure of bright and dark excitons in asymmetric droplet epitaxy GaAs/AlGaAs quantum dots

Abstract

We have calculated the exciton fine structure splittings (FSS) of asymmetric GaAs/AlGaAs quantum dots (QDs) obtained after Al droplet epitaxy and subsequent nanoholes formation followed by annealing and GaAs filling of nanoholes. We used a k • p model and considered the heavy-hole and light-hole mixing to calculate the electron-hole exchange interaction (EI). The two components, long-range (LR) and short-range (SR) of the EI, were deduced. The exciton fine structure is organized, as usual in zinc-blende compounds, into two groups of states: bright (optically active) and dark states. The bright-dark and bright-bright splittings contain LR and SR contributions, the LR part representing 5 to 68% of the total bright-dark splitting and 69 to 76% of the total bright-bright splitting for sizes experimentally explored. In QDs having C 2v symmetry, LR and SR contributions to dark-dark splitting have to be calculated at the second order of perturbation theory. A good agreement between the theory and experiment is obtained for QDs with different degrees of asymmetry, from QD having an isotropic shape to QD with a very anisotropic shape.

Dielectric effects, crystal field, and shape anisotropy tuning of the exciton fine structure of halide perovskite nanocrystals

“…In zinc-blende compounds, the EFS is organized into two doublets, a brightdoublet and dark-doublet. Both LR and SR interactions play a role to the dark-bright and bright-bright splittings with disparate orders of magnitude [94]. In halide perovskite semiconductors, only one single dark state exists, but three bright states contribute to the EFS.…”

Controlled Growth Mechanism of Ring-like In(Ga)As Quantum Dot Pairs on GaAs Ring-Ring-Disk Nanostructures Templates

“…The use of DE technology can obtain highly symmetrical quantum dots [26]. In addition, it was confirmed that the controlled growth of quantum dots can be achieved by changing experimental parameters during the growth process of QD, which hugely further expands its development in optoelectronic devices [27][28][29][30][31][32][33]. Although DE method has been proved to be very successful in the controlled growth of QD, there is still some works worth to do.…”