Radiative recombination processes in wide-band-gap II–VI quantum wells: the interplay between excitons and free carriers

Cingolani, R.; Calcagnile, Lucio; Coli, G.; Rinaldi, R.; Lomoscolo, M.; DiDio, M.; Franciosi, A.; Vanzetti, L.; LaRocca, G. C.; Campi, D.

doi:10.1364/josab.13.001268

Cited by 75 publications

(51 citation statements)

References 11 publications

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“…The model shows that upon temperature reduction, the exciton population starts to increase, becoming dominant below 120 K (see Fig. 4b) 13 .…”

Section: Resultsmentioning

confidence: 97%

“…Under thermodynamic equilibrium, there is a coexistence of free charges and excitons, and an interchange between the two species. The fraction of free charges (n FC ) vs. excitons (n exc ) is not only determined by the binding energy, which determines how long electron-hole pairs remain bound, but also by the excitation density (n), which influences how often electrons and holes meet to form excitons 13,14 .…”

Section: Resultsmentioning

confidence: 99%

“…Consequently, we can safely assume that the binding energy is independent of excitation density 23,25 . Within such an approximation, we can apply the law of mass action for Wannier-Mott excitons, as described by the Saha-Langmuir equation 13,14 . The fraction of free charges over the total density of excitation, x, for a 3D semiconductor can be expressed as 13 :…”

Section: Resultsmentioning

confidence: 99%

“…Subsequently, we use this value in the Saha equation, which governs ionization processes 13,14 , to estimate the equilibrium branching ratio between free charges and bound excitons as a function of temperature and charge density. We find that at equilibrium, following photoexcitation, there is a predominant fraction, near unity, of free charges in the PV operating regime.…”

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confidence: 99%

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Excitons versus free charges in organo-lead tri-halide perovskites

et al. 2014

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Excitonic solar cells, within which bound electron-hole pairs have a central role in energy harvesting, have represented a hot field of research over the last two decades due to the compelling prospect of low-cost solar energy. However, in such cells, exciton dissociation and charge collection occur with significant losses in energy, essentially due to poor charge screening. Organic-inorganic perovskites show promise for overcoming such limitations. Here, we use optical spectroscopy to estimate the exciton binding energy in the mixed-halide crystal to be in the range of 50 meV. We show that such a value is consistent with almost full ionization of the exciton population under photovoltaic cell operating conditions. However, increasing the total photoexcitation density, excitonic species become dominant, widening the perspective of this material for a host of optoelectronic applications.

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“…The model shows that upon temperature reduction, the exciton population starts to increase, becoming dominant below 120 K (see Fig. 4b) 13 .…”

Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Excitons versus free charges in organo-lead tri-halide perovskites

et al. 2014

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“…In simplest terms, the experiment gauges the excitonic strength of the e-h pair system against the predictable Landau quantization of the conduction and valence band edge states in a free electron-hole plasma (in one-electron approximation). In their study of optically pumped ZnCdSe lasers at cryogenic temperatures, Cingolani and co-workers earlier showed that, with sufficiently large electronic confinement (typically provided in QWs with the Cd-concentration x > 0.20), the quasi-2D system remains excitonic while supplying gain near the n = 1 HH resonance [23]. In these experiments, evidence for a Landau-type shift, dominated by the free electron contribution the confinement was relatively [16], one obtains an e-h pair density of 1.9 x 10 12 cm -2 in the ZnCdSe single QW.…”

Section: Optical Gain In Wide Gap Diode Lasers At Room Temperaturementioning

confidence: 99%

Physics of Stimulated Emission in Blue Semiconductor Lasers

Nurmikko

1999

Acta Phys. Pol. A

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Optically-Pumped Lasing of Doped ZnSe Epitaxial Layers Grown by Metal-Organic Vapour-Phase Epitaxy

Yablonskii¹,

Gurskii²,

Луценко³

et al. 1997

phys. stat. sol. (a)

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Laser action in undoped, nitrogen and chlorine doped ZnSe epitaxial layer has been achieved and investigated at pulse optical excitation by N2 laser radiation with a frequency of 1000 Hz from liquid nitrogen temperature up to near room temperature at 270 K. The highest value of ZnSe laser energy and power were E = 5×10−8 J and P = 5 W at Iexc = 800 kW/cm2. The laser line positions in doped samples ZnSe:Cl λ = 450.7 nm) and ZnSe:N λ = 451.2, 451.5, 452.0 and 455.5 nm at different excitation intensities) are shifted to the high wavelength side compared to undoped ZnSe λ = 449.8 nm). It was shown that doping ZnSe with both acceptor or donor impurities as well as using a ZnMgSSe barrier layer between the ZnSe layer and the substrate is favourable to increase PL efficiency and to decrease the laser threshold. The lowest threshold value (130 to 150 kW/cm2) was achieved in ZnSe:N grown with hydrogen carrier gas. The results obtained from measurements of the laser line positions as well as from the evaluation of the nonequilibrium carrier concentration proves that the ZnSe lasing mechanism under excitation by the N2 laser radiation is the recombination in an EHP. We found that under high excitation intensity a degradation of the excited region of the ZnSe takes place causing a decrease of the emission intensity. Under lower excitation power the PL intensity enhances during the course of irradiation.

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Radiative recombination processes in wide-band-gap II–VI quantum wells: the interplay between excitons and free carriers

Cited by 75 publications

References 11 publications

Excitons versus free charges in organo-lead tri-halide perovskites

Excitons versus free charges in organo-lead tri-halide perovskites

Physics of Stimulated Emission in Blue Semiconductor Lasers

Optically-Pumped Lasing of Doped ZnSe Epitaxial Layers Grown by Metal-Organic Vapour-Phase Epitaxy

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