Exciton dynamics in a GaAs quantum well

Eccleston, Richard; Strobel, R.; Rühle, W. W.; Kühl, J.; Feuerbacher, B. F.; Ploog, K.

doi:10.1103/physrevb.44.1395

Cited by 60 publications

(32 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This effect has been observed for excitons in GaAs QWs. 13 For n > 50x10 15 cm -3 this initial drop is absent since the carrier temperature is above T L and, therefore, the depletion does not occur. The main point we can extract from all the above discussions is that a critical temperature T c = 49 K can be identified, which sets a boundary in the spectral ( carriers cool down to T L through carrier-phonon interaction and it takes some time to reach the highest occupation of the lowest energy states, resulting in a delay for the PL to reach its maximum.…”

Section: (B)mentioning

confidence: 99%

“…The main point we can extract from all the above discussions is that a critical temperature T c = 49 K can be identified, which sets a boundary in the spectral ( carriers cool down to T L through carrier-phonon interaction and it takes some time to reach the highest occupation of the lowest energy states, resulting in a delay for the PL to reach its maximum. 13 As the excitation density is raised, the initial carrier temperature is higher and the cooling takes longer, leading to an increase of t r . 22,43,44 Only at the highest excitation densities, in the region where all the curves tend to approach a common value of t r ≈ 100 ps, the rise time is essentially characterized by electron-hole recombination for any lattice temperature, due to the effective carrier screening as already discussed above.…”

Section: (B)mentioning

confidence: 99%

“…The excitation density dependence of t r is strongly influenced by the sample characteristics and the specific excitation conditions of each experiment. 9 Thus, the literature provides a wide spectrum of experimental data with rise times increasing 10 or decreasing 7,8,[11][12][13] when raising the excitation density. On the other hand, in bulk III-V samples, these time-resolved studies are scarce [14][15][16][17] and ascertain that the free-exciton PL rise time is strongly influenced by trapping in localization centers.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Interplay of exciton and electron-hole plasma recombination on the photoluminescence dynamics in bulk GaAs

et al. 2006

View full text Add to dashboard Cite

We present a systematic study of the exciton/electron-hole plasma photoluminescence dynamics in bulk GaAs for various lattice temperatures and excitation densities. The competition between the exciton and electron-hole pair recombination dominates the onset of the luminescence. We show that the metal-to-insulator transition, induced by temperature and/or excitation density, can be directly monitored by the carrier dynamics and the time-resolved spectral characteristics of the light emission. The dependence on carrier density of the photoluminescence rise time is strongly modified around a lattice temperature of 49 K, corresponding to the exciton binding energy (4.2 meV). In a similar way, the rise-time dependence on lattice temperature undergoes a relatively abrupt change at an excitation density of 120-180x10 15 cm -3 , which is about five times greater than the calculated Mott density in GaAs taking into account many body corrections.

show abstract

Section: (B)mentioning

confidence: 99%

Section: (B)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Interplay of exciton and electron-hole plasma recombination on the photoluminescence dynamics in bulk GaAs

et al. 2006

View full text Add to dashboard Cite

show abstract

“…1 For a long time, photoluminescence (PL) at the spectral position of the 1s exciton resonance has been considered as evidence for the existence of excitons. The rise of the 1s PL after nonresonant excitation of a semiconductor was interpreted as buildup of an excitonic population [1,2,3,4,5,6], and the PL decay was used to describe exciton recombination [7,8]. However, recently a microscopic theory predicted that PL at the 1s resonance can also originate from correlated plasma emission [9].…”

mentioning

confidence: 99%

Excitonic Photoluminescence in Semiconductor Quantum Wells: Plasma versus Excitons

et al. 2004

View full text Add to dashboard Cite

Time-resolved photoluminescence spectra after nonresonant excitation show a distinct 1s resonance, independent of the existence of bound excitons. A microscopic analysis identifies excitonic and electron-hole plasma contributions. For low temperatures and low densities the excitonic emission is extremely sensitive to even minute optically active exciton populations making it possible to extract a phase diagram for incoherent excitonic populations. 1 For a long time, photoluminescence (PL) at the spectral position of the 1s exciton resonance has been considered as evidence for the existence of excitons. The rise of the 1s PL after nonresonant excitation of a semiconductor was interpreted as buildup of an excitonic population [1,2,3,4,5,6], and the PL decay was used to describe exciton recombination [7,8]. However, recently a microscopic theory predicted that PL at the 1s resonance can also originate from correlated plasma emission [9]. Accordingly, PL at the spectral position of the 1s resonance would not prove the existence of excitons, and previous interpretations may be in question. Indeed, in nonresonantly excited time resolved PL measurements the 1s resonance is developed on a sub-ps timescale at 100 K [10], much faster than any expected exciton formation time.Information about exciton formation can be gained by performing THz experiments [11].However, currently the THz results are inconclusive: Kaindl et al. [12] observed the buildup of the induced absorption corresponding to the excitonic 1s to 2p transition showing excitonic populations with formation times on a rather slow timescale of 100's of ps to ns. They claim to observe a nearly completely excitonic system 1 ns after excitation, while Chari et al. [13] only plasma contributions. Also, THz absorption is sensitive to both dark and bright excitons, and cannot answer if and how excitonic populations influence the PL.Here we address the following questions. Is the 1s PL ever dominated by plasma emission?If so, is it always dominated by plasma emission, i.e. what can we learn about excitonic populations from the 1s PL and nonlinear absorption?After ps continuum excitation, time resolved PL and corresponding probe absorption measurements are performed under identical conditions on a ns timescale. The sample (DBR42) consists of 20 MBE-grown 8 nm In 0.06 Ga 0.94 As quantum wells with 130 nm GaAs barriers; both sides are anti-reflection coated. This indium concentration places the 1s exciton resonance at 1.471 eV at 4 K, avoiding absorption in the bulk GaAs substrate that leads to impurity emission at 1.492 eV from unintentional carbon in the substrate. The results, checked on several other samples including a sample grown in a different MBE system, are insensitive to exciton linewidths or to interfacial or alloy disorder. Single-quantum-well data were noisier but exhibited a similar behavior, excluding significant radiative coupling effects.We excite nonresonantly 13.2 meV above the 1s resonance, into the heavy-hole continuum but below the light-h...

show abstract

“…A large number of studies have focused on the dynamics of exciton formation and relaxation [1][2][3][4][5][6][7][8][9][10][11][12]. It is generally accepted that the relaxation process following the optical creation of an electron-hole pair in the continuum may be separated into two steps [3]: first, in a time of the order of tens of picoseconds, the electron-hole pair relaxes its energy and forms an exciton with high kinetic energy.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Processes in Semiconductor Structures

Viña

1999

Acta Phys. Pol. A

View full text Add to dashboard Cite

We review the dynamics of some of the more relevant optical processes in semiconductor quantum wells. We concentrate on the linear regime and study the time evolution of the light emission, using time-resolved photoluminescence spectroscopy. In intrinsic materials, excitonic effects determine their optical properties. Here we describe the formation and recombination of excitons, and the dependence of these processes on lattice temperature, exciton density, and energy of the excitation light pulses. We also describe the dynamics of the exciton's spin by optical orientation experiments. We discuss the principal mechanisms responsible for the spin flip of the excitons and clarify the role of the exciton localization. Finally, we will show that exciton-exciton interaction produces a breaking of the spin degeneracy in two-dimensional semiconductors. In doped quantum wells, we show that the two spin components of an optically created two-dimensional electron gas are well described by the Fermi-Dirac distributions with a common temperature but different chemical potentials. The rate of the spin depolarization of the electron gas is found to be independent of the mean electron kinetic energy but accelerated by thermal spreading of the carriers.

show abstract

Exciton dynamics in a GaAs quantum well

Cited by 60 publications

References 11 publications

Interplay of exciton and electron-hole plasma recombination on the photoluminescence dynamics in bulk GaAs

Interplay of exciton and electron-hole plasma recombination on the photoluminescence dynamics in bulk GaAs

Excitonic Photoluminescence in Semiconductor Quantum Wells: Plasma versus Excitons

Ultrafast Processes in Semiconductor Structures

Contact Info

Product

Resources

About