Direct Evidence for a Bottleneck of Exciton-Polariton Relaxation in CdS

Heim, U.; Wiesner, P.

doi:10.1103/physrevlett.30.1205

Cited by 70 publications

(15 citation statements)

References 11 publications

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“…This result is in good qualitative agreement with estimations made on the basis of inequality (28). As can be seen from Fig.…”

Section: Spectroscopic Manifestation Of Free Exciton Lifetimesupporting

confidence: 91%

“…The model taking into account the peculiarities of polariton relaxation is quite reasonable and was confirnied by recent studies of polariton relaxation in CdS crystals [28]. However, it is quite possible that the results of Goto and Ueta can be explained on the basis of a more general assumption, namely supposing the absence of equilibrium between all points of the exciton band, as was proposed by Gross et al [29] for the interpretation of free exciton emission spectra in CdS crystals.…”

Section: Excitation Spectra Of Free Exciton Emissionmentioning

confidence: 91%

“…Therefore, the existence of hot exciton structure in the excitation spectrum provides us with the possibility to make some conclusions about the duration of exciton lifetime, since the values z, and zo are usually known from theoretical estimations, a t least with an accuracy up to an order of magnitude. At liquid helium temperatures za is usually of order s, whereas z, is shorter than s. As follows, condition ( 2 8 ) is satisfied at free exciton lifetimes of order za> ~n > zo 3 (28) 10-9 to 10-10 s. In real crystals the free exciton lifetime is determined mainly by the nonradiative decay and can considerably differ for various samples. This difference is demonstrated for CdS samples [ 161 in Pig.…”

Section: Spectroscopic Manifestation Of Free Exciton Lifetimementioning

confidence: 98%

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Hot excitons in semiconductors

Permogorov

1975

Physica Status Solidi (b)

213

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“…This result is in good qualitative agreement with estimations made on the basis of inequality (28). As can be seen from Fig.…”

Section: Spectroscopic Manifestation Of Free Exciton Lifetimesupporting

confidence: 91%

Section: Excitation Spectra Of Free Exciton Emissionmentioning

confidence: 91%

Section: Spectroscopic Manifestation Of Free Exciton Lifetimementioning

confidence: 98%

See 1 more Smart Citation

Hot excitons in semiconductors

Permogorov

1975

Physica Status Solidi (b)

213

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“…This is due to the low density of exciton states available at low wave vectors and to the reduction of the exciton/acoustic phonon scattering rate for high phonon wave vectors. 54 It should be noted that compared with an infinite crystal, the absence of dispersion along the confinement axis for excitons in our 200 nm thick GaN layer further hinders acoustic-phonon-assisted relaxation due to additional reduction in the density of available final states.…”

Section: Exciton Center-of-mass Quantizationmentioning

confidence: 99%

Intrinsic dynamics of weakly and strongly confined excitons in nonpolar nitride-based heterostructures

et al. 2011

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Both weakly and strongly confined excitons are studied by time-resolved photoluminescence in a nonpolar nitride-based heterostructure grown by molecular beam epitaxy on the a-facet of a bulk GaN crystal, with an ultralow dislocation density of 2 × 10 5 cm −2 . Strong confinement is obtained in a 4 nm thick Al 0.06 Ga 0.94 N/GaN quantum well (QW), whereas weakly confined exciton-polaritons are observed in a 200 nm thick GaN epilayer. Thanks to the low dislocation density, the effective lifetime of strongly confined excitons increases between 10 and 150 K, proving the domination of radiative recombination processes. Above 150 K the QW emission lifetime diminishes, whereas the decay time of excitons in the barriers increases, until both barrier and QW exciton populations become fully thermalized at 300 K. We conclude that the radiative efficiency of our GaN QW at 300 K is limited by nonradiative recombinations in the barriers. The increase of exciton-polariton coherence lengths caused by low dislocation densities allows us to observe and model the quantized emission modes in the 200 nm nonpolar GaN layer. Finally, the low-temperature phonon-assisted relaxation mechanisms of such center-of-mass quantized exciton-polaritons are described.

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“…As regards devices, although resonant luminescence was shown experimentally [56] and theoretically [57] to decay very fast, the nonresonant decay was shown to decay much slower. This was theoretically shown [29] to be due to the existence of a relaxation bottleneck for polaritons, arising from the diminishing DOS when the dispersion curve becomes photon-like in the resonant region, as for bulk excitonic polaritons [58]. As this would be the excitation situation encountered in electrical injection for devices, hopes of a new family of LED faded, although there might be some possibilities based on hybrid organic -inorganic microcavities by associating the good electrical injection properties of semiconductor materials with the ultrafast energy relaxation properties of organic ones [59].…”

Section: Featurementioning

confidence: 96%