One-dimensional exciton diffusion in GaAs quantum wires

Nagamune, Y.; Watabe, H.; Sogawa, F.; Arakawa, Y.

doi:10.1063/1.114484

Cited by 42 publications

(25 citation statements)

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“…[5], which is in agreement with the result presented here, there are, to the best of our knowledge, no ambipolar diffusion lengths reported for particle-seeded III-V NWs. However, we note that Nagamune et al [4] reported one of the longest exciton diffusion lengths, up to 2-4 mm, for GaAs wires. Their wires were quantum wires grown on V-grooves.…”

Section: Discussionmentioning

confidence: 95%

“…Using a Schottky contact and an electron beam, the diffusion of minority carriers in doped nanowires can be studied [3]. Local photo-excitation can also be used to study diffusion by photoluminescence imaging as long as the diffusion is longer than the excitation spot [4]. In this case, it is the combined diffusion of electrons and holes, the ambipolar diffusion, that is studied.…”

Section: Introductionmentioning

confidence: 99%

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Diffusion length measurements in axial and radial heterostructured nanowires using cathodoluminescence

Bolinsson

Mergenthaler

Samuelson

et al. 2011

Journal of Crystal Growth

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Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Diffusion length measurements in axial and radial heterostructured nanowires using cathodoluminescence

Bolinsson

Mergenthaler

Samuelson

et al. 2011

Journal of Crystal Growth

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“…One-dimensional exciton diffusion in excess of several microns has been observed in GaAs quantum wires. 18 In our case, exciton diffusion is likely driven by the potential gradient due to the Al distribution seen in Figures 2 and 3. The full width at half maximum (FWHM) of the μPL spectra was 62 meV at 10 K, and 120 meV at 300 K, significantly greater compared to the expected thermal broadening.…”

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confidence: 99%

Self-Directed Growth of AlGaAs Core−Shell Nanowires for Visible Light Applications

et al. 2007

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Be-doped Al 0.37 Ga 0.63 As nanowires (NWs) were grown in a molecular beam epitaxy system on GaAs (111)B substrates. Visible light emission was observed at room temperature in a confocal microscope and by micro-photoluminescence (μPL) measurements. μPL polarization measurements at 10 K, and diffusion measurements of NWs in solution, indicated emission from single NWs. Energy dispersive X-ray spectroscopy indicated a core-shell structure and Al composition gradient along the NW axis, producing a potential minimum for carrier confinement. The core-shell structure formed during growth as a consequence of the different Al and Ga adatom diffusion lengths.

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“…The excitation beam profile was shaped into a ring in real space with the use of two axicons and was projected to the microcavity through an objective lens (NA = 0.4) creating a polariton ring with a mean diameter of ∼ 20 µm on the sample (Supplementary Information, ?? ), which is of the order of the polariton mean free path in planar microcavities and much larger than the exciton diffusion length of the quantum wells of our sample [20,21]. The excitation beam intensity was modulated with an acousto-optic modulator at 1% duty cycle with a frequency of 10 kHz to reduce heating.…”

mentioning

confidence: 99%

Polariton condensation in an optically induced two-dimensional potential

et al. 2013

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We demonstrate experimentally the condensation of exciton-polaritons through optical trapping. The non-resonant pump profile is shaped into a ring and projected to a high quality factor microcavity where it forms a 2D repulsive optical potential originating from the interactions of polaritons with the excitonic reservoir. Increasing the population of particles in the trap eventually leads to the emergence of a confined polariton condensate that is spatially decoupled from the decoherence inducing reservoir, before any build up of coherence on the excitation region. In a reference experiment, where the trapping mechanism is switched off by changing the excitation intensity profile, polariton condensation takes place for excitation densities more than two times higher and the resulting condensate is subject to a much stronger dephasing and depletion processes.Strong coupling of cavity photons and quantum-well excitons gives rise to mixed light-matter bosonic quasiparticles called exciton-polaritons or polaritons [1]. Due to their photonic component, polaritons are several orders of magnitude lighter than atoms, which makes their condensation attainable at higher temperatures [2,3]. The manifestations of polariton condensation include polariton lasing [4], long-range spatial coherence [5,6] and stochastic vector polarisation [7]. In an ideal infinite twodimensional cavity the polariton gas is expected to undergo the Berezinsky-Kosterlitz-Thouless (BKT) phase transition [8], while in realistic structures, polaritons can condense in traps induced by random optical disorder [2] or mechanically created potentials [3,9]. Polariton condensation has also been observed in structures of lower dimensionality [10][11][12][13] where the structure itself acts as the trapping potential. Furthermore, the manipulation of polariton condensates by optically generated potentials has been previously shown [14][15][16]. In these works the condensation process was not assisted by the optical potential but used to localize an already formed polariton condensate.Here, we report on the first manifestation of polariton condensation assisted by an optically generated two dimensional potential. This scheme allows for the formation of a polariton condensate spatially separated from the excitation spot. Owing to the efficient trapping in the optical potential we observe a reduced excitation density threshold as well as higher coherence due to the decoupling of the condensate from the exciton reservoir. Polariton condensation prior to the build-up of coherence in the form of photon or polariton lasing [17,18] at the excitation area on the sample, decisively resolves the debate on the phase relation between the excitation laser and polariton condensate.We used a high quality factor GaAs/AlGaAs microcavity containing four separate triplets of 10 nm GaAs quantum wells and has a vacuum Rabi splitting of 9 meV [19], held at ∼ 6.5 K in a cold-finger cryostat and excited non-resonantly at the first reflection minimum above the cavity stop band with a s...

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One-dimensional exciton diffusion in GaAs quantum wires

Cited by 42 publications

References 0 publications

Diffusion length measurements in axial and radial heterostructured nanowires using cathodoluminescence

Diffusion length measurements in axial and radial heterostructured nanowires using cathodoluminescence

Self-Directed Growth of AlGaAs Core−Shell Nanowires for Visible Light Applications

Polariton condensation in an optically induced two-dimensional potential

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