Influence of confinement on biexciton binding in semiconductor quantum dot ensembles measured with two-dimensional spectroscopy

Moody, Galan; Singh, Rohan; Li, Hebin; Акимов, И. А.; Bayer, М.; Reuter, D.; Wieck, A. D.; Bracker, Allan S.; Gammon, D.; Cundiff, Steven T.

doi:10.1103/physrevb.87.041304

Cited by 64 publications

(76 citation statements)

References 34 publications

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“…For other QDs, like InAs Stranski-Krastanov, the binding energy is usually slightly smaller. For InAs QDs in the strong confinement regime, the XX binding energy was found to be independent of the emission energy, while it increases for weakly confined GaAs natural QDs [33]. Fig.…”

Section: A Power-dependent Microphotoluminescencementioning

confidence: 99%

Exciton footprint of self-assembled AlGaAs quantum dots in core-shell nanowires

et al. 2014

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Quantum-dot-in-nanowire systems constitute building blocks for advanced photonics and sensing applications. The electronic symmetry of the emitters impacts their function capabilities. Here we study the fine structure of gallium-rich quantum dots nested in the shell of GaAs-Al 0.51 Ga 0.49 As core-shell nanowires. We used optical spectroscopy to resolve the splitting resulting from the exchange terms and extract the main parameters of the emitters. Our results indicate that the quantum dots can host neutral as well as charged excitonic complexes and that the excitons exhibit a slightly elongated footprint, with the main axis tilted with respect to the long axis of the host nanowire. GaAs-Al x Ga 1−x As emitters in a nanowire are particularly promising for overcoming the limitations set by strain in other systems, with the benefit of being integrated in a versatile photonic structure.

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Section: A Power-dependent Microphotoluminescencementioning

confidence: 99%

Exciton footprint of self-assembled AlGaAs quantum dots in core-shell nanowires

et al. 2014

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“…Since the lower transitions (|0 ↔ |1 and |0 ↔ |2 ) are excited by the optical field to first order in perturbation theory, while the upper transitions (|1 ↔ |3 and |2 ↔ |3 ) contribute to third order only if the lower transitions have been excited, the electronic and optical properties of the upper transitions dictate the interaction strength [30]. Specifically, we consider excitation-induced shift (EIS) and excitation-induced dephasing (EID) effects, which have been used to explain coherent exciton coupling in semiconductor quantum wells [31,32] and quantum dots [33,34]. EIS and EID correspond to the real and imaginary part of the renormalization energy when interaction effects are considered, thus both effects must appear simultaneously, in principle.…”

Section: Fig 2 (Color Online) (A) Two-dimensional Spectrum Featurinmentioning

confidence: 99%

Coherent Electronic Coupling in Atomically ThinMoSe2

et al. 2014

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We report the first direct spectroscopic evidence for coherent electronic coupling between excitons and trions in atomically thin transition metal dichalcogenides, specifically monolayer MoSe2. Signatures of coupling appear as isolated cross-peaks in two-color pump-probe spectra, and the lineshape of the peaks reveals that the coupling originates from many-body interactions. Excellent agreement between the experiment and density matrix calculations suggests the formation of a correlated exciton-trion state due to their coupling. PACS numbers: 73.20.Mf,78.47.jg Atomically thin transition metal dichalcogenides (TMDs) have emerged as an interesting class of twodimensional materials due to their unique optical properties. For example, some materials (e.g. MoS 2 ) exhibit a crossover from an indirect-to-direct gap semiconductor as the material thickness is reduced to one atomic layer [1], consequently enhancing the photoluminescence efficiency [2]. Valley-specific optical selection rules [3][4][5] dictated by time reversal and spatial inversion symmetries in monolayer structures have been observed, and such selection rules have been electrically controlled in bilayers [6]. These attributes make TMDs particularly intriguing for tunable and flexible valleytronic and photonic devices [7].A striking feature in the linear optical spectra of atomically thin TMDs is the presence of pronounced exciton resonances (Coulomb-bound electron-hole pairs), even at room temperature. The large binding energy of excitons, estimated to be hundreds of meV [8,9], as well as tightlybound trions (an exciton bound with an extra electron or hole) [10,11] arises from reduced dielectric screening in the thickness direction of the film [12]. It is reasonable to speculate that enhanced Coulomb interactions responsible for the large exciton and trion binding energies should also lead to strong coherent coupling among these quasiparticles. The presence or absence of coupling between excitonic states in conventional semiconductors is known to significantly influence energy transfer [13], photon emission statistics [14], and quantum-logic operations [15] in quantum wells, wires, and dots. It is particularly imperative to understand the properties of these intrinsically many-body states in TMDs as they are inevitably present in all optical devices such as photovoltaics [16,17], detectors [18], and modulators [19,20].The existence and manifestation of electronic coupling is challenging to study experimentally since nonlinear spectroscopy techniques are required. Previous experiments thus far have provided limited information on the effects of phase-space filling, exciton-carrier broadening effects [21,22], inter-excitonic scattering [23], valley relaxation dynamics [24], and biexciton formation [25] in TMDs.In this Letter, we provide clear evidence for coherent exciton-trion interactions in monolayer MoSe 2 using twocolor ultrafast pump-probe spectroscopy. In a high quality sample with spectrally well-resolved exciton and trion resonances, spectrosc...

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“…A particular example is ultrafast coherent control of exciton complexes confined in semiconductor nanostructures [1] which may be used for manipulating quantum states [2][3][4] or even storing quantum information [5,6]. For an inhomogeneous ensemble of twolevel systems (TLS) such as quantum dots (QDs) the information retrieval induces echoes for the recovered signal [7][8][9]. To be of practical use, the echo formation time needs to be determined with high accuracy.…”

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Photon echo transients from an inhomogeneous ensemble of semiconductor quantum dots

et al. 2016

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An ensemble of quantum dot excitons may be used for coherent information manipulation. Due to the ensemble inhomogeneity any optical information retrieval occurs in form of a photon echo.We show that the inhomogeneity can lead to a significant deviation from the conventional echo timing sequence. Variation of the area of the initial rotation pulse, which generates excitons in a dot sub-ensemble only, reveals this complex picture of photon echo formation. We observe a retarded echo for π/2 pulses, while for 3π/2 the echo is advanced in time as evidenced through monitoring the Rabi oscillations in the time-resolved photon echo amplitude from (In,Ga)As/GaAs self-assembled quantum dot structures and confirmed by detailed calculations.

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Influence of confinement on biexciton binding in semiconductor quantum dot ensembles measured with two-dimensional spectroscopy

Cited by 64 publications

References 34 publications

Exciton footprint of self-assembled AlGaAs quantum dots in core-shell nanowires

Exciton footprint of self-assembled AlGaAs quantum dots in core-shell nanowires

Coherent Electronic Coupling in Atomically ThinMoSe2

Photon echo transients from an inhomogeneous ensemble of semiconductor quantum dots

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