Dynamic characteristics of the exciton and the biexciton in a single InGaN quantum dot

Amloy, Supaluck; Moskalenko, E. S.; Eriksson, Martin; Karlsson, K. F.; Chen, Y. T.; Chen, K. H.; Hsu, Hsu Cheng; Hsiao, Ching‐Lien; Chen, L. C.; Holtz, Per-Olof

doi:10.1063/1.4742343

Cited by 19 publications

(15 citation statements)

References 32 publications

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“…The biexciton emission is different from exciton emission by its binding energy, which is typically negative in InGaN QDs due to the repulsive exciton-exciton Coulomb interaction between the two excitons [11,[19][20][21][22][23][24][25][26]. This effectively leads to a lowering of the potential barrier for a biexciton by its binding energy, which can be extracted from the overall spectral linewidth, as explained in Sec.…”

Section: Principles Of Carrier Dynamicsmentioning

confidence: 99%

“…Then we will use this model to explain the peculiar g (2) 0 -τ correlation of multiple QDs with the same diameter at 10 K in Sec. VII C and T -dependence of g In our QDs [11], as well as in many other InGaN/GaN QDs [19][20][21][22][23][24][25][26], the biexciton emission typically has higher energy than the exciton emission, i.e. the biexciton has a negative binding energy −B XX .…”

Section: Biexciton Dynamics and Single-qd G (2) Propertiesmentioning

confidence: 99%

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Carrier dynamics in site- and structure-controlled InGaN/GaN quantum dots

et al. 2014

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We report on the carrier dynamics in InGaN/GaN dot-in-nanowire quantum dots revealed by systematic mapping between optical properties and structural parameters of the quantum dots. Such a study is made possible by using quantum dots with precisely controlled locations and sizes. We show that the carrier dynamics is governed by two competing mechanisms: 1) excitons are protected from surface recombination by a potential barrier formed due to strain-relaxation at the sidewall surface; 2) excitons can overcome the potential barrier by tunnelling and thermal activation. This carrier dynamics model successfully explains the following surprising experimental findings on individual quantum dots. Firstly, there exist strong statistical correlations among multiple optical properties of many individual quantum dots, despite variations of these properties resulting from inevitable structural variations among the quantum dots. Secondly, the antibunching property of quantum dot emission exhibits abnormal ladle-shaped dependence on the decay time and temperature. Our results can guide the way toward nitride-based high temperature singlephoton emitters and nano-photonic devices.

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Section: Principles Of Carrier Dynamicsmentioning

confidence: 99%

Section: Biexciton Dynamics and Single-qd G (2) Propertiesmentioning

confidence: 99%

Carrier dynamics in site- and structure-controlled InGaN/GaN quantum dots

et al. 2014

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“…Hence we assign peak X to the single exciton emission, and peak XX to the biexciton-to-exciton transition. 22,23 The large negative binding energies of XX (> 10 meV) are commonly observed in III-N QDs [24][25][26][27][28][29][30][31] . It is due to the residual strain, even in dots with such small sizes, which enhances the repulsive excitonexciton Coulomb interaction 26 .…”

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confidence: 99%

How much better are InGaN/GaN nanodisks than quantum wells—Oscillator strength enhancement and changes in optical properties

Zhang

Lee

Teng

et al. 2014

Applied Physics Letters

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We show over 100-fold enhancement of the exciton oscillator strength as the diameter of an InGaN nanodisk in a GaN nanopillar is reduced from a few micrometers to less than 40 nm, corresponding to the quantum dot limit. The enhancement results from significant strain relaxation in nanodisks less than 100 nm in diameter. Meanwhile, the radiative decay rate is only improved by 10 folds due to strong reduction of the local density of photon states in small nanodisks. Further increase in the radiative decay rate can be achieved by engineering the local density of photon states, such as adding a dielectric coating.InGaN/GaN quantum wells (QWs), with a bandgap tunable over the full visible spectral range, play a vital role in high efficiency visible light emitting diodes (LEDs) and laser diodes 1 . InGaN/GaN quantum dots (QDs) also hold the promise as high temperature quantum photonic devices 2,3 . Unfortunately, a large, strain-induced electric field in III-N heterostructures often severely suppresses the oscillator strength of the exciton and, hence, the radiative decay rate and the internal quantum efficiency (IQE). Since strain is relaxed near free surfaces, nanodisks (NDs) in nanowires, which has a large surfaceto-volume ratio, have been widely considered as a promising solution for improving the IQE of InGaN/GaN photonic devices [4][5][6][7][8][9][10][11] . The accompanying improvement in the radiative decay rate is also important for realizing ultrafast singlephoton sources using InGaN/GaN QDs 3,12 .Despite the observation of enhancements in photoluminescence (PL) intensity and decay rate in InGaN/GaN NDs 4,10,13 , the size-dependent behavior of IQE η int and radiative decay rate γ r , mostly affected by the emitter's oscillator strength f os , remains unclear. Experimental studies using top-down nanopillars reported up to ten-fold enhancement in emission intensity only in nanopillars larger than 100 nm in diameter 10 . However, theoretical studies predicted that strain relaxation is most significant only in the region < 20 nm from the sidewall, suggesting significant improvement of IQE could be possible in small disks ∼ 40 nm in size 9 . Furthermore, no comparisons so far have taken into account the influence of external optical efficiencies on the measured PL intensity, such as input laser absorption efficiency η abs , local density of photon states (LDPS) ρ 14,15 and emission collection efficiency η col 16 , which hinders the extraction of η int , γ r as well as f os .In this work, we systematically compare the PL properties of NDs with diameters ranging from 15 nm to 2 µm. We first present two NDs at the two ends of the diameter range, highlighting their fundamentally different spectral responses to the excitation-induced carrier-screening of piezoelectric fields. We then examine how PL energy, decay time and intensity changes continuously with ND diameter reduction, from which we extract the enhancement of f os , γ r , and η int through careful analysis of various external optical efficiencies.The sample w...

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“…Since the energy of the XX emission is 0.8 meV lower than that of the X emission, the biexciton binding energy for the single quantum‐confined structure in N‐polar InGaN/GaN MQW is found to be 0.8 meV. Bardoux et al reported a positive biexciton binding energy of 13 meV in a localization center in single InGaN/GaN quantum disks, whereas a negative biexciton binding energy of −15.8 meV was reported for a single InGaN quantum dot . This discrepancy can be explained by the changes in the internal electric field .…”

Section: Resultsmentioning

confidence: 99%

Biexciton Emission From Single Quantum‐Confined Structures in N‐Polar (000‐1) InGaN/GaN Multiple Quantum Wells

Takamiya

Yagi

Yaguchi

et al. 2017

Physica Status Solidi (b)

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We report on the observation of biexciton luminescence from single quantum‐confined structures in N‐polar InGaN/GaN multiple quantum wells (MQWs) grown on c‐plane sapphire by metalorganic vapor phase epitaxy. Sharp emission lines are observed at different positions of the sample by micro‐photoluminescence (μ‐PL) mapping. The density of sharp emission lines is ≈0.3 μm−2, which is comparable with the inversion domain (ID) density found from transmission electron microscope observation, suggesting that the sharp emission lines originate from single quantum‐confined structures formed by the combination of quantum well and IDs in N‐polar InGaN/GaN MQWs. It is found from the excitation power dependence of the PL intensity of two adjacent sharp lines that the intensity of biexciton luminescence at the lower energy side shows a quadratic dependence on the excitation power while that of exciton luminescence at the higher energy side increased linearly with increasing excitation power. The biexciton binding energy is found to be 0.8 meV.

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Dynamic characteristics of the exciton and the biexciton in a single InGaN quantum dot

Cited by 19 publications

References 32 publications

Carrier dynamics in site- and structure-controlled InGaN/GaN quantum dots

Carrier dynamics in site- and structure-controlled InGaN/GaN quantum dots

How much better are InGaN/GaN nanodisks than quantum wells—Oscillator strength enhancement and changes in optical properties

Biexciton Emission From Single Quantum‐Confined Structures in N‐Polar (000‐1) InGaN/GaN Multiple Quantum Wells

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