Fine structure of neutral and charged excitons in self-assembled In(Ga)As/(Al)GaAs quantum dots

Bayer, М.; Ortner, G.; Stern, O.; Kuther, A.; Gorbunov, A. V.; Forchel, A.; Hawrylak, Paweł; Fafard, S.; Hinzer, Karin; Reinecke, T. L.; Walck, Scott N.; Reithmaier, J.P.; Klopf, F.; Schäfer, F. P.

doi:10.1103/physrevb.65.195315

Cited by 1,071 publications

(1,154 citation statements)

References 101 publications

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“…2). In the case of both excitonic complexes the zero-field emission contains two lines split by the energy related to the anisotropic part of the exchange interaction between the electron and the heavy hole 10 . Such emission lines can be seen separately in two perpendicular linear polarizations of the detection.…”

Section: B Anisotropic Exchange Splitting Of X and Xxmentioning

confidence: 99%

Comparison of magneto-optical properties of various excitonic complexes in CdTe and CdSe self-assembled quantum dots

Kobak

Smoleński

Goryca

et al. 2016

J. Phys.: Condens. Matter

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We present a comparative study of two self-assembled quantum dot (QD) systems based on II-VI compounds: CdTe/ZnTe and CdSe/ZnSe. Using magneto-optical techniques we investigated a large population of individual QDs. The systematic photoluminescence studies of emission lines related to the recombination of neutral exciton X, biexciton XX, and singly charged excitons (X + , X − ) allowed us to determine average parameters describing CdTe QDs (CdSe QDs): X-XX transition energy difference 12 meV (24 meV); fine-structure splitting δ1 = 0.14 meV (δ1 = 0.47 meV); g-factor g = 2.12 (g = 1.71); diamagnetic shift γ = 2.5 µeV/T 2 (γ = 1.3 µeV/T 2 ). We find also statistically significant correlations between various parameters describing internal structure of excitonic complexes.

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Section: B Anisotropic Exchange Splitting Of X and Xxmentioning

confidence: 99%

Comparison of magneto-optical properties of various excitonic complexes in CdTe and CdSe self-assembled quantum dots

Kobak

Smoleński

Goryca

et al. 2016

J. Phys.: Condens. Matter

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“…This polarization behavior is characteristic for an AEI-induced FSS of the bright neutral exciton states. 14 As illustrated in Fig.2(c), without AEI the two bright states of the neutral excitons are two-fold degenerate with the eigenstates of |+1 and |-1 that are  σ and  σ active, respectively. The electron spin is preserved in these hh exciton states, namely, electron spin-down in |+1 and electron spinup in |-1.…”

Section: Resultsmentioning

confidence: 97%

“…It has now been well established that an anisotropic exchange interaction (AEI) can split the doublet of the bright neutral exciton states into two spinmixed, linearly polarized |H and |V exciton states, commonly referred to as a fine-structuresplitting (FSS). 14 In highly strained self-assembled InAs/(Al)GaAs QDs, FSS has been shown to be in the range of 40-1000 µeV 15 . This strong variation in FSS was suggested to be governed by effects of strain-and shape-induced wave function asymmetry of the excitons.…”

mentioning

confidence: 99%

Exciton Fine-Structure Splitting in Self-Assembled Lateral InAs/GaAs Quantum-Dot Molecular Structures

et al. 2015

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Fine-structure splitting (FSS) of excitons in semiconductor nanostructures is a key parameter that has significant implications in photon entanglement and polarization conversion between electron spins and photons, relevant to quantum information technology and spintronics. Here, we investigate exciton FSS in self-organized lateral InAs/GaAs quantum-dot molecular structures (QMSs) including laterally aligned double quantum dots (DQDs), quantum-dot clusters (QCs), and quantum rings (QRs), by employing polarization-resolved microphotoluminescence (μPL) spectroscopy. We find a clear trend in FSS between the studied QMSs depending on their geometric arrangements, from a large FSS in the DQDs to a smaller FSS in the QCs and QRs. This trend is accompanied by a corresponding difference in the optical polarization directions of the excitons between these QMSs, namely, the bright-exciton lines are linearly polarized preferably along or perpendicular to the [11̅0] crystallographic axis in the DQDs that also defines the alignment direction of the two constituting QDs, whereas in the QCs and QRs, the polarization directions are randomly oriented. We attribute the observed trend in the FSS to a significant reduction of the asymmetry in the lateral confinement potential of the excitons in the QRs and QCs as compared with the DQDs, as a result of a compensation between the effects of lateral shape anisotropy and piezoelectric field. Our work demonstrates that FSS strongly depends on the geometric arrangements of the QMSs, which effectively tune the degree of the compensation effects and are capable of reducing FSS even in a strained QD system to a limit similar to strain-free QDs. This approach provides a pathway in obtaining high-symmetry quantum emitters desirable for realizing photon entanglement and spintronic devices based on such nanostructures, utilizing an uninterrupted epitaxial growth procedure without special requirements for lattice-matched materials combinations, specific substrate orientations, and nanolithography

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“…In the former case for structures such as In(Ga)As/GaAs [5], the confinement energies in all three spatial directions typically exceed the electron-hole Coulomb correlation energy (exciton binding energy) of photoexcited electrons and holes by at least an order of magnitude. On the other hand, in the case of lateral fluctuation quantum dots strong confinement exists only along the growth direction, and the confinement in the lateral directions arises from monolayer differences in well width; in the AlGaAs/GaAs system this is typically a few meV, while the quasi-2D exciton binding energy is approximately 10 meV.…”

Section: Introduction/backgroundmentioning

confidence: 99%

Internal Transitions of Charged Excitons in AlGaAs/GaAs Lateral Fluctuation Quantum Dots

et al. 2004

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Low temperature measurements of magneto-photoluminescence and optically detected resonance spectroscopy in magnetic fields up to 10 T were carried out on GaAs/Al 0.3 Ga 0.7 As quantum well samples grown by molecular beam epitaxy with lateral fluctuation quantum dots produced by growth interruption. Monolayer fluctuations of the quantum well width form lateral quantum dots for which confinement energies are less than Coulomb correlation energies. Five different width quantum wells (2.8-14.1 nm) were grown in a single sample, doped in the barriers with Si donors to allow for photoluminescence of both excitons and trions. We report studies of the optically detected resonance spectra associated with the ensemble photoluminescence of all of the wells including observation of bound-to-continuum internal transitions of trions, both singlet and triplet, and electron cyclotron resonance for the wider wells, which also show a clear bound-to-bound triplet transition. The latter is forbidden by magnetic translational invariance, but can be seen in these samples because this symmetry is broken by the lateral fluctuations, whose characteristic dimensions are greater than the trion orbit size. The two narrowest wells show strong broad optically detected resonance signals associated with inhomogeneously broadened internal transitions of the strongly correlated trions in the lateral dots. The optically detected resonance signals peak well below the calculated positions of electron cyclotron resonance. As expected for localized carriers and excitons, there is no free electron cyclotron resonance. We also present preliminary measurements of optically detected resonance spectra from a single dot.

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Fine structure of neutral and charged excitons in self-assembled In(Ga)As/(Al)GaAs quantum dots

Cited by 1,071 publications

References 101 publications

Comparison of magneto-optical properties of various excitonic complexes in CdTe and CdSe self-assembled quantum dots

Comparison of magneto-optical properties of various excitonic complexes in CdTe and CdSe self-assembled quantum dots

Exciton Fine-Structure Splitting in Self-Assembled Lateral InAs/GaAs Quantum-Dot Molecular Structures

Internal Transitions of Charged Excitons in AlGaAs/GaAs Lateral Fluctuation Quantum Dots

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