Dimensional crossover of free exciton diffusion in etched GaAs wire structures

Bieker, S.; Stühler, R.; Kießling, T.; Ossau, W.; Molenkamp, L. W.

doi:10.1063/1.4931369

Cited by 3 publications

(3 citation statements)

References 17 publications

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“…The low-density tails of the reservoir distribution extend several tens of micrometres away from the hot spot. This indicates that the transport of the reservoir particles, which have a large excitonic component, exceeds the transport length of bare excitons (∼ 1 − 2µm [40][41][42] ) by an order of magnitude. These results are consistent with the recently reported extended transport of bottleneck polaritons 25 .…”

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confidence: 99%

“…where n(x, y,t) is the density of the diffusing carriers at position (x, y) and time t, D represents the diffusion coefficient (diffusivity) for the carrier density, τ denotes the lifetime of the carriers, and g(x, y,t) stands for the local rate of generation of the carriers. An analytical solution for 2D stationary distribution of carriers created by a point source g(x, y) = δ (x − ξ )δ (y − η) is given by 32 : where K 0 is the zeroth-order modified Bessel function of the second kind and the effective diffusion length is defined as…”

mentioning

confidence: 99%

“…In order to fit this distribution function to the spatial distribution of the carrier density in the experiment, one has to convolve Eq. ( 2) with the laser profile on the sample, which acts as an initial source of the carrier density 32 . In our analysis, we assume that at low exciton-polariton densities the main contribution to the effective potential originates from the reservoir density, thus E eff (x) ∝ n R (x) 19 .…”

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confidence: 99%

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Spatial distribution of an optically induced excitonic reservoir below exciton-polariton condensation threshold

Boozarjmehr¹,

Steger²,

West³

et al. 2019

Preprint

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Spatial distribution of an optically induced excitonic reservoir below exciton-polariton condensation threshold

Boozarjmehr¹,

Steger²,

West³

et al. 2019

Preprint

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Lateral carrier diffusion in InGaAs/GaAs coupled quantum dot-quantum well system

Pieczarka

Syperek

Biegańska

et al. 2017

Applied Physics Letters

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The lateral carrier diffusion process is investigated in coupled InGaAs/GaAs quantum dot-quantum well (QD-QW) structures by means of spatially resolved photoluminescence spectroscopy at low temperature. Under non-resonant photo-excitation above the GaAs bandgap, the lateral carrier transport reflected in the distorted electron-hole pair emission profiles is found to be mainly governed by high energy carriers created within the 3D density of states of GaAs. In contrast, for the case of resonant excitation tuned to the QW-like ground state of the QD-QW system, the emission profiles remain unaffected by the excess kinetic energy of carriers and local phonon heating within the pump spot. The lateral diffusion lengths are determined and present certain dependency on the coupling strength between QW and QDs. While for a strongly coupled structure the diffusion length is found to be around 0.8 μm and monotonically increases up to 1.4 μm with the excitation power density, in weakly coupled structures, it is determined to ca. 1.6 μm and remained virtually independent of the pumping power density.

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Carrier diffusion as a measure of carrier/exciton transfer rate in InAs/InGaAsP/InP hybrid quantum dot–quantum well structures emitting at telecom spectral range

Rudno‐Rudziński

Biegańska

Misiewicz

et al. 2018

Applied Physics Letters

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We investigate the diffusion of photo-generated carriers (excitons) in hybrid two dimensional–zero dimensional tunnel injection structures, based on strongly elongated InAs quantum dots (called quantum dashes, QDashes) of various heights, designed for emission at around 1.5 μm, separated by a 3.5 nm wide barrier from an 8 nm wide In0.64Ga0.36As0.78P0.22 quantum well (QW). By measuring the spectrally filtered real space images of the photoluminescence patterns with high resolution, we probe the spatial extent of the emission from QDashes. Deconvolution with the exciting light spot shape allows us to extract the carrier/exciton diffusion lengths. For the non-resonant excitation case, the diffusion length depends strongly on excitation power, pointing at carrier interactions and phonons as its main driving mechanisms. For the case of excitation resonant with absorption in the adjacent QW, the diffusion length does not depend on excitation power for low excitation levels since the generated carriers do not have sufficient excess kinetic energy. It is also found that the diffusion length depends on the quantum-mechanical coupling strength between QW and QDashes, controlled by changing the dash size. It influences the energy difference between the QDash ground state of the system and the quantum well levels, which affects the tunneling rates. When that QW–QDash level separation decreases, the probability of capturing excitons generated in the QW by QDashes increases, which is reflected by the decreased diffusion length from approx. 5 down to 3 μm.

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Dimensional crossover of free exciton diffusion in etched GaAs wire structures

Cited by 3 publications

References 17 publications

Spatial distribution of an optically induced excitonic reservoir below exciton-polariton condensation threshold

Spatial distribution of an optically induced excitonic reservoir below exciton-polariton condensation threshold

Lateral carrier diffusion in InGaAs/GaAs coupled quantum dot-quantum well system

Carrier diffusion as a measure of carrier/exciton transfer rate in InAs/InGaAsP/InP hybrid quantum dot–quantum well structures emitting at telecom spectral range

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