Power-dependent spin amplification in (In, Ga)As/GaAs quantum well via Pauli blocking by tunnel-coupled quantum dot ensembles

Chen, Shula; Kiba, Takayuki; Yang, Xiaojie; Takayama, Junichi; Murayama, Akihiro

doi:10.1063/1.4945740

Cited by 9 publications

(7 citation statements)

References 27 publications

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“…PL spectra from the ground state (GS) are measured using a conventional CCD detector; the spectral peak energies are indicated by the black arrows in the figures. The weak but sharp PL spectral peak observed at the higher-energy region originates from the QW [20][21][22]. A thicker QW sample exhibits a higher QW-PL intensity, accompanied by a shift of the PL peak toward lower energies and higher CPD.…”

Section: Resultsmentioning

confidence: 96%

“…The QD-QW-coupled structures are grown by molecular beam epitaxy; the details are described in previous studies [20][21][22]. Briefly, 400-nm-thick GaAs buffers are grown on GaAs (001) substrates at 580°C.…”

Section: Methodsmentioning

confidence: 99%

“…We reveal that the electron wavefunctions localized in each QD can be laterally coupled when the two-dimensional-(2D)-QW potential is close to a thin tunneling barrier. This tunnel-coupled QD-QW hybrid nanosystem is of significance as electron spins are laterally transferred among QDs through spin-conserving tunneling, which can be precisely controlled only by a simple structural parameter, the QW thickness t. We had already established the crystal growth of such a tunnel-coupled QD-QW structure [20,21]. Our previous studies using the QD-QW structures revealed an efficient and ultrafast spin injection from the QW into QDs with injection time constants smaller than 10 ps and spin-conservation rates higher than 90%.…”

Section: Introductionmentioning

confidence: 99%

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Persistent High Polarization of Excited Spin Ensembles During Light Emission in Semiconductor Quantum-Dot-Well Hybrid Nanosystems

et al. 2018

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We demonstrate persistent high degrees of spin polarization (SPD) up to 70% during light emission in (In 1-x Ga x)As quantum-dot-well (QD-QW) hybrid nanosystems, where QD excited states are laterally tunnel coupled through the adjacent two-dimensional QW potential depending on the QW thickness. Spinpolarized electrons are photo-excited by using circularly polarized light pulses. The decay time of spin relaxation, obtained by that of the SPD, is 70 times larger than the photoluminescence decay time. The temporally constant SPD is sustained by a selective transfer of minority spins among QDs after flipping from the majority spins, which is promoted by a moderate state filling of lower-energy spin sublevels in surrounding QDs. The spin transfer times are deduced as functions of the QW thickness and excited-spin density. These results can provide a precise control of lateral interdot spin-transfer dynamics and resultant suppression of spin relaxation in QD ensembles.

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Section: Resultsmentioning

confidence: 96%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Persistent High Polarization of Excited Spin Ensembles During Light Emission in Semiconductor Quantum-Dot-Well Hybrid Nanosystems

et al. 2018

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“…The carriers were first captured in the 2D QW and then injected into the QDs via thermally stable spin‐conserved tunneling. [ 29,30 ] The excitation laser power was less than 400 µW (corresponding to the excitation power density of ≈100 W cm −2 ) to suppress the state‐filling effect in the QDs, [ 37 ] which could affect the spin polarization properties. For temperature‐dependent PL measurements, the samples were kept in a liquid helium cooled cryostat.…”

Section: Methodsmentioning

confidence: 99%

Efficient Room‐Temperature Voltage Control of Picosecond Optical Spin Orientation Using a III‐V Semiconductor Nanostructure

Park

Hiura

Takayama

et al. 2022

Adv Elect Materials

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Manipulation of the optical spin orientation in semiconductors is a key technology for realizing spin‐based photoelectric information processing. Application of magnetic field is a simple method to control the spin polarization degree through Zeeman splitting. However, this effect can only be achieved at cryogenic temperatures and in a strong magnetic field. Here, room‐temperature voltage control of optical polarization in the range of 3–15%, corresponding to a 12–60% change in relative spin polarization is demonstrated. For this, a III‐V semiconductor quantum dot tunnel coupled with a quantum well spin reservoir is used. The spin‐flip scattering rate within quantum dots is electric‐field‐controlled in the time domain of several tens of picoseconds. This is achieved by precise control of the tunnel injection efficiency of electrons and holes via coupled potential modification. The findings will pave the way for the generation of ultrafast spin‐modulated optical signals by the electric field effect.

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“…Based on our PL and PLE results, we believe that our hybrid nanostructure is in the strong coupling regime, where the electron wave-function or the electron probability density is smeared out from both the QW and the QD confining potentials to penetrate into each other. As a result, a very fast carrier tunneling time from the QW into the QDs is experimentally observed [39][40].…”

Section: Herementioning

confidence: 99%

Carrier dynamics in hybrid nanostructure with electronic coupling from an InGaAs quantum well to InAs quantum dots

Wang

Sheng

Yuan

et al. 2018

Journal of Luminescence

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Carrier dynamics including carrier relaxation and tunneling within a coupled InAs quantum dot (QD)-In 0.15 Ga 0.85 As quantum well (QW) hybrid nanostructure are investigated using photoluminescence (PL) spectroscopy. This coupled hybrid nanostructure shows a single PL peak from the QD emission at low excitation intensity and a band filling behavior is observed as the excitation intensity increases, suggesting that there exists a channel to capture carriers from the QW to the QDs. Time resolved PL (TRPL) measurements extract a carrier tunneling time of 103.7ps, which is only one third of the theoretical prediction. A double-channel resonant carrier tunneling mechanism from the QW to the wetting layer and to the fifth excited state of the QDs and then carrier relaxation into lower discrete QD energy states is proposed to explain this fast 2 carrier tunneling. The double-channel resonant carrier tunneling mechanism is qualitatively supported through the analysis of the excitation-dependent PL spectra as well as the PL excitation spectra. These results enrich our understanding of carrier dynamics in coupled QD and QW hybrid structures.

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Power-dependent spin amplification in (In, Ga)As/GaAs quantum well via Pauli blocking by tunnel-coupled quantum dot ensembles

Abstract: Articles you may be interested in

Cited by 9 publications

References 27 publications

Persistent High Polarization of Excited Spin Ensembles During Light Emission in Semiconductor Quantum-Dot-Well Hybrid Nanosystems

Persistent High Polarization of Excited Spin Ensembles During Light Emission in Semiconductor Quantum-Dot-Well Hybrid Nanosystems

Efficient Room‐Temperature Voltage Control of Picosecond Optical Spin Orientation Using a III‐V Semiconductor Nanostructure

Carrier dynamics in hybrid nanostructure with electronic coupling from an InGaAs quantum well to InAs quantum dots

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