Biexcitonic molecules survive excitons at the Mott transition

Shahmohammadi, Mehran; Jacopin, Gwenolé; Rossbach, Georg; Levrat, Jacques; Feltin, E.; Carlin, J.-F.; Ganière, Jean‐Daniel; Butté, R.; Grandjean, N.; Deveaud, B.

doi:10.1038/ncomms6251

Cited by 17 publications

(16 citation statements)

References 22 publications

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“…4(b), below 0.95 μJ cm −2 , the FWHM of the PL spectra and the peak energy remain nearly constant around 38 meV and 3.15 eV, respectively, whereas, above 0.95 μJ cm −2 , the FWHM gets wider by 20 meV and the peak energy shifts toward higher energy by 6 meV. The significant spectral broadening and the slight blueshift in the emission energy are the signatures of phase-space filling and provide further evidence of the fact that the initially injected carrier density is close to the Mott density, which is typically observed to occur between 5 × 10 11 and 2 × 10 12 cm −2 for GaN based QWs [20,31]. Since the temperature has a significant impact on the recombination dynamics and on the equilibrium between the exciton gas and the e-h plasma, we performed TRPL experiments at 4 and 300 K under identical conditions.…”

Section: Resultsmentioning

confidence: 99%

“…To analyze the 300 K data, we start from I pl (t = 0, 300 K) and τ r,300 K . The parameters that we have used are: n 0 = 1 × 10 18 cm −3 as obtained from the capacitance-voltage measurements, n Mott = 1 × 10 12 cm −2 as measured in our previous reports [20,31], and τ r,x,4 K = τ eff,4 K ≈ 500 ps. Finally, the unknown average recombination rate of the e-h plasma 1/τ 0 is 2 × 10 5 s −1 , as obtained from the best fit of the radiative lifetime under high injection.…”

Section: Results Of the Modeling And Discussionmentioning

confidence: 99%

“…where E b0 is the exciton binding energy at low carrier density [24] and n Mott is the 2D critical Mott density, which is about 10 12 cm −2 for GaN-based QWs [20,31]. Since we investigate InGaN QWs with a relatively low In content (<10%), we assume that the critical Mott density remains unchanged.…”

Section: Modeling Of Carrier-density-dependent Recombination Dynamentioning

confidence: 99%

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Carrier-density-dependent recombination dynamics of excitons and electron-hole plasma in m -plane InGaN/GaN quantum wells

et al. 2016

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We study the carrier-density-dependent recombination dynamics in m-plane InGaN/GaN multiple quantum wells in the presence of n-type background doping by time-resolved photoluminescence. Based on Fermi's golden rule and Saha's equation, we decompose the radiative recombination channel into an excitonic and an electron-hole pair contribution, and extract the injected carrier-density-dependent bimolecular recombination coefficients. Contrary to the standard electron-hole picture, our results confirm the strong influence of excitons even at room temperature. Indeed, at 300 K, excitons represent up to 63 ± 6% of the photoexcited carriers. In addition, following the Shockley-Read-Hall model, we extract the electron and hole capture rates by deep levels and demonstrate that the increase in the effective lifetime with injected carrier density is due to asymmetric capture rates in presence of an n-type background doping. Thanks to the proper determination of the density-dependent recombination coefficients up to high injection densities, our method provides a way to evaluate the importance of Auger recombination.

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Section: Resultsmentioning

confidence: 99%

Section: Results Of the Modeling And Discussionmentioning

confidence: 99%

Section: Modeling Of Carrier-density-dependent Recombination Dynamentioning

confidence: 99%

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Carrier-density-dependent recombination dynamics of excitons and electron-hole plasma in m -plane InGaN/GaN quantum wells

et al. 2016

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“…Since the excitonic Mott transition occurs in a solidstate environment, which hosts a plethora of physical phenomena, it is essential to rule out alternative mechanisms that could have explained our data. A common practice in literature is to analyze PL spectra on a semilogarithmic scale [16,52]. The signature of EHplasma in direct quantum wells is considered an exponentially decaying high-energy tail of the PL peak.…”

Section: Appendix C: Ruling Out Other Possible Mechanismsmentioning

confidence: 99%

Observation of the exciton Mott transition in the photoluminescence of coupled quantum wells

et al. 2016

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Indirect excitons in coupled quantum wells have long radiative lifetimes and form a cold quasitwo-dimensional population suitable for studying collective quantum effects. Here we report the observation of the exciton Mott transition from an insulating (excitons) to a conducting (ionized electron-hole pairs) phase, which occurs gradually as a function of carrier density and temperature. The transition is inferred from spectral and time-resolved photoluminescence measurements around a carrier density of 2 × 10 10 cm −2 and temperatures of 12-16 K. An externally applied electric field is employed to tune the dynamics of the transition via the quantum-confined Stark effect. Our results provide evidence of a gradual nature of the exciton Mott transition.

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“…b) and the PL peak intensity linearly increased with the excitation fluence. This is an indication of exciton emission, for which emission peak is almost excitation independent inspite of bandgap decrease .…”

Section: Resultsmentioning

confidence: 89%

Excitation‐dependent carrier dynamics in Al‐rich AlGaN layers and multiple quantum wells

Ščajev

Miasojedovas

Jarašiūnas

et al. 2015

Physica Status Solidi (b)

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The combined temporally, spatially and spectrally-resolved optical techniques, namely the photoluminescence, light induced transient grating, and differential reflectivity were used for investigation of excitation-dependent PL efficiency, exciton lifetime, and diffusion coefficient in Si-doped Al-rich multiple quantum wells and epilayers at various temperatures. Novel features of carrier recombination and in-plane diffusion were observed. Low-excitation radiative lifetime of 1-2 ns was found temperature-independent in 80-150 K interval, while it sublinearly decreased with excitation at excess carrier densities above 10 18 cm À3 . The lifetime decrease correlated with the increase of diffusion coefficient, indicating excitation-enhanced delocalization of localized excitons and therefore enhanced capture to nonradiative centers. The droop of photoluminescence efficiency with excitation was the strongest at 80-150 K due to strong delocalisation at low-temperatures, while at higher temperatures the thermal activation prevailed in photoluminescence excitation dependence. The photoluminescence efficiency quenching at T > 200 K provided rather high activation energies of $100 and 160 meV for Al-rich multiple quantum wells and epilayers, correspondingly.

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Biexcitonic molecules survive excitons at the Mott transition

Cited by 17 publications

References 22 publications

Carrier-density-dependent recombination dynamics of excitons and electron-hole plasma in m -plane InGaN/GaN quantum wells

Carrier-density-dependent recombination dynamics of excitons and electron-hole plasma in m -plane InGaN/GaN quantum wells

Observation of the exciton Mott transition in the photoluminescence of coupled quantum wells

Excitation‐dependent carrier dynamics in Al‐rich AlGaN layers and multiple quantum wells

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