Size-dependent line broadening in the emission spectra of single GaAs quantum dots: Impact of surface charge on spectral diffusion

Ha, Neul; Mano, Takaaki; Chou, Ying Lin; Wu, Yu Nien; Cheng, Shun‐Jen; Bocquel, Juanita; Koenraad, P. M.; Ohtake, Akihiro; Sakuma, Yoshiki; Sakoda, Kazuaki; Kuroda, Takashi

doi:10.1103/physrevb.92.075306

Cited by 38 publications

(50 citation statements)

References 42 publications

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“…The polarization state of the input light is adjusted to maximize the detection efficiency. Note that we attach a high-index hemispherical lens (n = 2) to the sample surface to increase the light collection efficiency 19 . Thanks to the efficient setup together with the bright sample we achieve a maximum count rate as high as ∼50 kHz under saturation conditions.…”

Section: Arxiv:200107329v1 [Cond-matmes-hall] 21 Jan 2020mentioning

confidence: 99%

Single photon emission from droplet epitaxial quantum dots in the standard telecom window around a wavelength of 1.55 μm

Ha¹,

Mano²,

Dubos³

et al. 2020

Appl. Phys. Express

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We study the luminescence dynamics of telecom wavelength InAs quantum dots grown on InP(111)A by droplet epitaxy. The use of the ternary alloy InAlGaAs as a barrier material leads to photon emission in the 1.55 µm telecom C-band. The luminescence decay is well described in terms of the theoretical interband transition strength without the impact of nonradiative recombination. The intensity autocorrelation function shows clear anti-bunching photon statistics. The results suggest that our quantum dots are useful for constructing a practical source of single photons and quantum entangled photon pairs. This is the version of the article before peer review, as submitted to Applied Physics Express. The final published version will be available as an Open Access article from the journal's site.A source of single photons and quantum entangled photon pairs is a key device in vast quantum technologies. Semiconductor quantum dots are expected to serve as photon sources that can be operated very efficiently and deterministically. Numerous efforts have already been made to develop a practical quantum dot photon source. However, photon emission in the standard telecom band, particularly around a wavelength of 1.55 µm, which is the maximum transmission window of silica optical fibers, is a material challenge. Careful growth optimization is required to achieve a 1.55 µm emission 1-10 . Nevertheless, the well-known quantum dot growth based on the Stranski-Krastanow mode leads to an asymmetric dot shape, which is not favorable for entangled pair generation.The problem is ideally solved by using droplet epitaxy, which offers considerable freedom regarding the choice of materials and substrates 11 . The application of a C 3v symmetric (111)A surface to the growth substrate results in the creation of almost perfectly symmetric quantum dots, which can work in both the visible wavelength region 12,13 and the infrared telecom wavelength region 14,15 . Recently, the emission wavelength has been extended beyond 1.5 µm for InAs dots embedded in InAlGaAs on InP(111)A 16 . However, the previous samples were not sufficiently optimized: the dot density was too high for a single quantum dot to be isolated using standard micro optics. Moreover, the dot size distribution is relatively large so that careful dot selection is required to find a dot that emits at 1.55 µm.Here, we extend the droplet epitaxy scheme to achieve a purely 1.55 µm photon emission. We introduce the high temperature crystallization protocol, which has recently been applied to the GaAs material system 17,18 , to the InAs/InP material system in order to improve the a) Electronic mail: ha.neul@nims.go.jp b) Electronic mail: kuroda.takashi@nims.go.jp FIG. 1. (Color online) (b) The luminescence spectra of a large ensemble of InAs quantum dots in In0.52Al0.12Ga0.36As /InP(111)A at 12 K at different excitation powers. (b) The luminescence spectra of a single isolated InAs dot with a cw excitation of 40 nW. We focus on this dot in our time-resolved study. The inset shows an atomic fo...

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Section: Arxiv:200107329v1 [Cond-matmes-hall] 21 Jan 2020mentioning

confidence: 99%

Single photon emission from droplet epitaxial quantum dots in the standard telecom window around a wavelength of 1.55 μm

Ha¹,

Mano²,

Dubos³

et al. 2020

Appl. Phys. Express

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“…The emission linewidths of III-nitride QDs are often limited by fast spectral diffusion (occurring on nanosecond time scales [38][39][40][41], and in this case, the narrower linewidths of the further confined samples can possibly be explained by a smaller volume of the surrounding material, which is statistically likely to contain a smaller number of charge trap sites. 27,42 The emission from the sample is stable and exhibits only a small degree of spectral wandering as can be seen in Figure 3B, which presents 600 seconds of continuous data acquisition (600 spectra acquired with 1-second integration time per spectrum). We note that similar measurements performed on the annealed nanowire heterostructures (without the final growth step) exhibit large discrete spectral jumps in the millielectron-volt range, most likely due to strong interactions between charges confined in the InGaN nanostructures and charge fluctuations on the nanowire surface.…”

Section: Figure 3 Photoluminescence (Pl) Andmentioning

confidence: 96%

Single‐photon emission from a further confined InGaN/GaN quantum disc via reverse‐reaction growth

Sun

Wang

Sheng

et al. 2019

Quantum Engineering

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We demonstrate high-purity single-photon emission from a high-quality and further confined InGaN (indium gallium nitride) quantum disc in a GaN (gallium nitride) nanowire fabricated by an unconventional and versatile reverse-reaction fabrication method. This further confined structure exhibits single-photon emission with a g (2) (0) value of 0.11 at 8 K with a sub-nanosecond radiative lifetime. The formation of the further confined structure using this versatile reverse-reaction fabrication approach overcomes many limitations in conventional self-assembled III-nitride nanowires and, thus, exhibits a strong potential application as a high-purity single-photon source. KEYWORDSInGaN, molecular beam epitaxy, nanowires, quantum dots, reverse-reaction growth, self-assembled, single-photon emission Quantum Engineering. 2019;1:e20.wileyonlinelibrary.com/journal/que2

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“…A top barrier thickness above 100 nm is crucial for suppressing spectral diffusion from fluctuating surface charges. 40 We report that the majority of the neutral exciton lines have a linewidth below the resolution of the experimental setup (40 µeV).…”

mentioning

confidence: 92%

“…We expect that the QD morphology will be maintained after capping as well, showing sharp interfaces. 39,40 A direct assessment of the optical quality and the investigation of the electronic structure of these nanostructures required an in-depth analysis through single dot PL. Figure 2(a) shows a typical emission spectrum of our QDs under above-barrier excitation.…”

mentioning

confidence: 99%

High-Yield Fabrication of Entangled Photon Emitters for Hybrid Quantum Networking Using High-Temperature Droplet Epitaxy

et al. 2017

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Several semiconductor quantum dot technologies have been investigated for the generation of entangled photon pairs. Among the others, droplet epitaxy enables control of the shape, size, density, and emission wavelength of the quantum emitters. However, the fraction of entanglement-ready quantum dots that can be fabricated with this method is still limited to values around 5%, and matching the energy of the entangled photons to atomic transitionsa promising route towards quantum networking -remains an outstanding challenge.Here, we overcome these hurdles by introducing a modified approach to droplet epitaxy on a high symmetry (111)A substrate, where the fundamental crystallization step is performed at a significantly higher temperature as compared to previous reports. Our method improves drastically the yield of entanglement-ready photon sources near the emission wavelength of interest, which can be as high as 95% thanks to the low values of fine structure splitting and radiative lifetime, together with the reduced exciton dephasing offered by the choice of GaAs/AlGaAs materials. The quantum dots are designed to emit in the operating spectral region of Rb-based slow-light media, providing a viable technology for quantum repeater stations.Keywords: Quantum dots, entanglement, droplet epitaxy, fine structure splitting, rubidium, resonant two-photon excitation Under the ongoing effort to develop practical quantum technologies, the search for a suitable entangled photon source is an active research direction, as it plays a role in key quantum communication protocols and some approaches to quantum computation. 1,2 Above all, it is a fundamental requirement for the realization of repeaters capable to transfer quantum entanglement over long distances.Epitaxial quantum dots (QDs) are a promising alternative to parametric down-converters, given their ability to generate photons ondemand with high efficiency and their compatibility with semiconductor foundries. 3,4 In order to use QD entanglement resources in reallife technologies, two main roadblocks have to be overcome. The first is related to the difficulty of consistently finding emitters capable 1 arXiv:1710.03483v1 [cond-mat.mes-hall]

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Size-dependent line broadening in the emission spectra of single GaAs quantum dots: Impact of surface charge on spectral diffusion

Cited by 38 publications

References 42 publications

Single photon emission from droplet epitaxial quantum dots in the standard telecom window around a wavelength of 1.55 μm

Single photon emission from droplet epitaxial quantum dots in the standard telecom window around a wavelength of 1.55 μm

Single‐photon emission from a further confined InGaN/GaN quantum disc via reverse‐reaction growth

High-Yield Fabrication of Entangled Photon Emitters for Hybrid Quantum Networking Using High-Temperature Droplet Epitaxy

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