In-plane radiative recombination channel of a dark exciton in self-assembled quantum dots

Smoleński, T.; Kazimierczuk, T.; Goryca, M.; Jakubczyk, Tomasz; Kłopotowski, Ł.; Cywiński, Łukasz; Wojnar, P.; Golnik, A.; Kossacki, P.

doi:10.1103/physrevb.86.241305

Cited by 46 publications

(45 citation statements)

References 27 publications

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“…This prediction of a z-polarized component is indeed confirmed by the experimental results displayed in figures 22(e) and (f), where this z-polarized spectral line is positioned 200 μeV from the single exciton transitionX . 10 We note that the existence of a z-polarized component in the emission spectrum of an exciton was also experimentally observed for asymmetric selfassembled CdTe/ZnTe QDs [51] and theoretically confirmed using a tight-binding model [52].…”

Section: Discussionsupporting

confidence: 62%

Spectral signatures of high-symmetry quantum dots and effects of symmetry breaking

et al. 2015

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High symmetry epitaxial quantum dots (QDs) with three or more symmetry planes provide a very promising route for the generation of entangled photons for quantum information applications. The great challenge to fabricate nanoscopic high symmetry QDs is further complicated by the lack of structural characterization techniques able to resolve small symmetry breaking. In this work, we present an approach for identifying and analyzing the signatures of symmetry breaking in the optical spectra of QDs. Exciton complexes in InGaAs/AlGaAs QDs grown along the [111]B crystalline axis in inverted tetrahedral pyramids are studied by polarization resolved photoluminescence spectroscopy combined with lattice temperature dependence, excitation power dependence and temporal photon correlation measurements. By combining such a systematic experimental approach with a simple theoretical approach based on a point-group symmetry analysis of the polarized emission patterns of each exciton complex, we demonstrate that it is possible to achieve a strict and coherent identification of all the observable spectral patterns of numerous exciton complexes and a quantitative determination of the fine structure splittings of their quantum states. This analysis is found to be particularly powerful for selecting QDs with the highest degree of symmetry (C 3v and D h 3 ) for potential applications of these QDs as polarization entangled photon sources. We exhibit the optical spectra when evolving towards asymmetrical QDs, and show the higher sensitivity of certain exciton complexes to symmetry breaking.

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Section: Discussionsupporting

confidence: 62%

Spectral signatures of high-symmetry quantum dots and effects of symmetry breaking

et al. 2015

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“…In a neutral quantum dot electrons ↑(↓) and heavy holes ⇑(⇓) in a spin up (down) state along the growth axis Oz form either optically forbidden "dark" 16,23,24,40,[42][43][44][45][46][47][48][49][50][51] excitons |⇑↑ (|⇓↓ ) with spin projection +2(−2), or "bright" excitons |⇑↓ (|⇓↑ ) with +1(−1) spin projection. The structure of the exciton eigenstates in the dot is determined by the electron-hole (e − h) exchange interaction 11,42 .…”

Section: Photoluminescence Spectroscopy Of Dark and Bright Excitmentioning

confidence: 99%

Dynamic nuclear polarization in InGaAs/GaAs and GaAs/AlGaAs quantum dots under nonresonant ultralow-power optical excitation

et al. 2013

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Article:Puebla, J., Chekhovich, E.A., Hopkinson, M. orcid.org/0000-0002-8097-6913 et al. (4 more authors) (2013) Dynamic nuclear polarization in InGaAs/GaAs and GaAs/AlGaAs quantum dots under nonresonant ultralow-power optical excitation. Physical Review B, 88 (4 ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. We study experimentally the dependence of dynamic nuclear spin polarization on the power of non-resonant optical excitation in two types of individual neutral semiconductor quantum dots: InGaAs/GaAs and GaAs/AlGaAs. We show that the mechanism of nuclear spin pumping via second order recombination of optically forbidden ("dark") exciton states recently reported in InP/GaInP quantum dots [Phys. Rev. B 83, 125318 (2011)] is relevant for material systems considered in this work. In the InGaAs/GaAs dots this nuclear spin polarization mechanism is particularly pronounced, resulting in Overhauser shifts up to ∼80 µeV achieved at optical excitation power ∼1000 times smaller than the power required to saturate ground state excitons. The Overhauser shifts observed at low-power optical pumping in the interface GaAs/AlGaAs dots are generally found to be smaller (up to ∼40 µeV). Furthermore in GaAs/AlGaAs we observe dot-to-dot variation and even sign reversal of the Overhauser shift which is attributed to dark-bright exciton mixing originating from electron-hole exchange interaction in dots with reduced symmetry. Nuclear spin polarization degrees reported in this work under ultra-low power optical pumping are comparable to those achieved by techniques such as resonant optical pumping or above-gap pumping with high power circularly polarized light. Dynamic nuclear polarization via second-order recombination of "dark" excitons may become a useful tool in single quantum dot applications, where manipulation of the nuclear spin environment or electron spin is required.

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“…As expected, in each case the anisotropic electron-hole exchange interaction led to splitting of the emission line into two components of orthogonal linear polarizations. Possible deviation from the orthogonality of these linear polarizations is introduced by the valence band mixing [17][18][19] , which for the QD in Fig. 1 was found to be smaller than 3%.…”

Section: Polarization-resolved Photoluminescence Of Cdte/znte Qdsmentioning

confidence: 99%

Optical study of electron-electron exchange interaction in CdTe/ZnTe quantum dots

et al. 2013

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We present an experimental study of electron-electron exchange interaction in self-assembled CdTe/ZnTe quantum dots based on the photoluminescence measurements. The character and strength of this interaction are obtained by simultaneous observation of various recombination channels of a doubly negatively charged exciton X 2− , including previously unrecognized emission lines related to the electron-singlet configuration in the final state. A typical value of the electron singlettriplet splitting, which corresponds to the exchange integral of electron-electron interaction, has been determined as 20.4 meV with a spread of 1.4 meV across the wide population of quantum dots. We also evidence an unexpected decrease of energy difference between the singlet and triplet states under a magnetic field in Faraday geometry.

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In-plane radiative recombination channel of a dark exciton in self-assembled quantum dots

Cited by 46 publications

References 27 publications

Spectral signatures of high-symmetry quantum dots and effects of symmetry breaking

Spectral signatures of high-symmetry quantum dots and effects of symmetry breaking

Dynamic nuclear polarization in InGaAs/GaAs and GaAs/AlGaAs quantum dots under nonresonant ultralow-power optical excitation

Optical study of electron-electron exchange interaction in CdTe/ZnTe quantum dots

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