Effect of growth interruption in 1.55 <i>μ</i>m InAs/InAlGaAs quantum dots on InP grown by molecular beam epitaxy

Jung, Daehwan; Ironside, Daniel J.; Bank, Seth R.; Gossard, A. C.; Bowers, John E.

doi:10.1063/1.5031772

Cited by 13 publications

(18 citation statements)

References 29 publications

(32 reference statements)

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“…Moreover a detailed comparison with a particular experiment 54 should include a comprehensive knowledge of nanostructure's morphology, which is often near impossible to obtain. 17,18,21,57 Nevertheless one can speculate here that obtained results strongly suggest that is is unlikely for [110] elongated quantum dashes to achieve a very small fine structure splitting unless other phenomena such as alloying due to annealing or composition intermixing are included into the consideration 27,38 or external fields are applied. 32 Otherwise growers should aim for non-elongated 13 or weakly [110] elongated nanostructures, where small elongation along [110] axis 64 should lead to the reduced fine structure splitting, by minimizing the anisotropic contribution due to strain.…”

Section: Excitonic Fine Structure: Bright and Dark Excitonsmentioning

confidence: 78%

“…[9][10][11] The realm of InAs/InP nanostructures is rich and varies from more conventional cylindrical self-assembled, 12,13 and nanowire quantum dots [14][15][16] to rather unconventional semiconductor nanostructures with characteristic large in-plane elongation, known as quantum dashes. [17][18][19][20][21][22][23][24][25][26][27] Quantum dashes have demonstrated their potential for utilization in e.g. lasers and amplifiers 19,20,28 or single photon emitters.…”

Section: Introductionmentioning

confidence: 99%

“…Further, often the experiment is pestered by uncertainties due to inhomogeneous broadening in the ensemble studies 54 or unavoidable alloy randomness effects originating from the specifics of the epitaxial growth, 54,55 in particular growth on mixed composition substrates (e.g. InGaAlAs 27,56 ). A detailed knowledge (chemical composition, intermixing, actual dimensions) of nanostructure's morphology, is often very much complicated, if not impossible to obtain.…”

Section: Introductionmentioning

confidence: 99%

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From quantum dots to quantum dashes: Excitonic spectra of highly elongated InAs/InP nanostructures

Zieliński

2019

Phys. Rev. B

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A transition from a cylindrical quantum dot to a highly elongated quantum dash is theoretically studied here with an atomistic approach combining empirical tight binding for single particle states and configuration interaction method for excitonic properties. Large nanostructure shape anisotropy leads to a peculiar trend of the bright exciton splitting, which at certain point is quenched with further shape elongation, contradicting predictions of simplified models. Moreover strong shape elongation promotes pronounced optical activity of the dark exciton, that can reach substantial 1% fraction of the bright exciton intensity without application of any external fields. An atomistic calculation is augmented with a elementary phenomenological model expressed in terms of lighthole exciton add-mixture increasing with the shape deformation. Finally, exctionic complexes X − , X + , and XX are studied as well and the correlations due to presence of higher excited states are identified as a key-factor affecting excitonic binding energies and the fine structure.

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Section: Excitonic Fine Structure: Bright and Dark Excitonsmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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From quantum dots to quantum dashes: Excitonic spectra of highly elongated InAs/InP nanostructures

Zieliński

2019

Phys. Rev. B

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“… 7 , 11 , 17 , 18 This is particularly important for InAs/InP nanostructures, which are promising candidates for quantum emitters at 1.3 or telecommunication relevant wavelengths 19 – 22 . Notably, InAs/InP nanostructures can be fabricated in various ways, including self-assembled and nanowire quantum dots 23 – 27 of quasi-cylindrical shapes, as well as strongly elongated dots 28 – 42 , sometimes referred to as quantum dashes. Similarly to cylindrically-shaped dot systems, quantum dashes have the potential for applications 30 , 31 , 43 – 45 combined with considerable tuning capabilities 46 , 47 .…”

Section: Introductionmentioning

confidence: 99%

Vanishing fine structure splitting in highly asymmetric InAs/InP quantum dots without wetting layer

Zieliński

2020

Sci Rep

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Contrary to simplified theoretical models, atomistic calculations presented here reveal that sufficiently large in-plane shape elongation of quantum dots can not only decrease, but even reverse the splitting of the two lowest optically active excitonic states. Such a surprising cancellation of bright-exciton splitting occurs for shape-anisotropic nanostructures with realistic elongation ratios, yet without a wetting layer, which plays here a vital role. However, this non-trivial effect due to shapeelongation is strongly diminished by alloy randomness resulting from intermixing of InAs quantumdot material with the surrounding InP matrix. Alloying randomizes, and to some degree flattens the shape dependence of fine-structure splitting giving a practical justification for the application of simplified theories. Finally, we find that the dark-exciton spectra are rather weakly affected by alloying and are dominated by the effects of lateral elongation. Quantum dots 1,2 are man-made semiconductor nanostructures that come in a wide variety of types 3-5 , and are extensively studied with interest driven by both basic scientific curiosity as well as promising applications in quantum information 6 , computing 7,8 , and cryptography 9. Apart from the elementary excitations, electrons and holes, quantum dots can confine interacting electron-hole pairs, namely excitons. 10 An emission cascade from a two exciton (biexciton) state, through two indistinguishable exciton states should lead to the emission of polarization entangled photon pairs. 9,11-13 However, in realistic quantum dots the intermediate exciton state is often split by the electron-hole exchange interaction 14-16 hindering the efficiency of the entanglement generation. This energetic difference between the two bright exciton states, known as the fine-structure splitting or the bright exciton splitting (BES) is typically (10-100 µeV) much larger than the emission linewidth (∼ 1 µeV). Tailoring the BES in nanostructures is thus essential due to its relevance for photon entanglement generation. 7,11,17,18 This is particularly important for InAs/InP nanostructures, which are promising candidates for quantum emitters at 1.3 or 1.55 µm telecommunication relevant wavelengths 19-22. Notably, InAs/InP nanostructures can be fabricated in various ways, including self-assembled and nanowire quantum dots 23-27 of quasi-cylindrical shapes, as well as strongly elongated dots 28-42 , sometimes referred to as quantum dashes. Similarly to cylindrically-shaped dot systems, quantum dashes have the potential for applications 30,31,43-45 combined with considerable tuning capabilities 46,47. The manipulation of the BES aimed towards generation of entangled photon pairs is a vital and broad research area with significant efforts have been made utilizing post-growth annealing 48,49 , spectral filtering 9 , sample selection 50,51 , growth of highly symmetric structures 24,26,52-54 , and the application of external electric 55,56 , magnetic 18,57,58 , and strain fields 59-61. With respect t...

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“…In this Letter, we demonstrate high-performance InAs QDash microring lasers in the 1.55 μm telecom window under continuous electrical injection. The InAs QDashes employed in these lasers undergo a growth interruption process to ripen InAs nanostructures, which enhanced their optical properties . A WGM ring cavity with vertical etched profile and smooth sidewall surface was fabricated, allowing strong lateral optical confinement and low scattering losses.…”

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confidence: 99%

Low-Threshold Continuous-Wave Operation of Electrically Pumped 1.55 μm InAs Quantum Dash Microring Lasers

et al. 2018

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Densely integrated devices on a single chip enable both complex functionality and economy of scale. With a small footprint, microcavities with self-assembled InAs quantum dashes (QDashes) use minimal real estate cost while offering full photonic functionality. Here, the first roomtemperature-continuous-wave (CW) operation of electrically pumped InAs QDash microring lasers in the 1.55 μm telecom window is reported. CW lasing up to 55 °C has been achieved with a low threshold current density of 528 A/cm 2 . The ring laser has only a few unique modes with an extinction ratio over 26 dB for the primary mode. The reduced carrier diffusion length of the QDash active region suppresses the sidewall surface recombination. Feasibility of device miniaturization was demonstrated, with the lowest threshold being 3.5 mA. Since microring cavities do not require feedback mirrors, their compact size and resulting low thresholds make them the ideal candidate for an on-chip light source in optical datacom interconnects.

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Effect of growth interruption in 1.55 μm InAs/InAlGaAs quantum dots on InP grown by molecular beam epitaxy

Cited by 13 publications

References 29 publications

From quantum dots to quantum dashes: Excitonic spectra of highly elongated InAs/InP nanostructures

From quantum dots to quantum dashes: Excitonic spectra of highly elongated InAs/InP nanostructures

Vanishing fine structure splitting in highly asymmetric InAs/InP quantum dots without wetting layer

Low-Threshold Continuous-Wave Operation of Electrically Pumped 1.55 μm InAs Quantum Dash Microring Lasers

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