Evidence of strong Auger recombination in semiconductor-doped glasses

Rougemont, F. de; Frey, R.; Roussignol, Philippe; Ricard, D.; Flytzanis, C.

doi:10.1063/1.97746

Cited by 63 publications

(14 citation statements)

References 13 publications

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“…The decay of the transients measured with a pump intensity of 0.32 mJ/cm 2 clearly becomes slower at longer delay times. This behavior might suggest a strongly density-dependent recombination mechanism, such as Auger recombination [34][35][36]. However, plotting (1/Ac~) z as a function of time delay [36] does not give a straight line, indicating that the decay is not dominated by an Auger term.…”

Section: Time Dependencementioning

confidence: 83%

Ultrafast dynamics of carrier-induced absorption changes in highly-excited CdSe nanocrystals

et al. 1996

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Abstract. We use femtosecond time-resolved transmission spectroscopy to study the density and time dependence of transient absorption changes of CdSe nanocrystals. Our data show pronounced absorption saturation up to complete bleaching of the lowest optical transition. At high carrier density the nonlinear spectra show several peaks that can be related to the two lowest quantized electron states. Thetime dependence of the carrier-induced absorption changes indicates an ultrafast relaxation process within the strongly broadened absorption lines. 78.47.+p; 73.20.Dx; 71.35.+z In recent years, there has been a strong interest in lowdimensional semiconductor structures such as quantum wells, quantum wires, and quantum dots. The electronic states in these artificial materials are strongly influenced by size quantization effects, which occur when the dimensions of the structures become comparable to or smaller than the exciton Bohr radius aB. Then, the electronic and optical properties of the structures become determined by their geometry. Thus, the controlled fabrication of low-dimensional semiconductor structures may allow to obtain materials with predefined properties. PACS:In addition, size quantization has been shown to lead to a significant enhancement of excitonic effects and to strongly enhanced optical nonlinearities in two-dimensional quantum wells, where the carriers are confined in only one dimension [1]. It can be expected that a confinement of carriers in two or three dimensions will lead to a further enhancement of the optical nonlinearities. Therefore, semiconductor quantum dots appear as a promising new material for nonlinear optical applications. It has been found that semiconductor crystallites with radii on the order of a few nanometer, denoted as nanocrystals (NCs), can be rather easily produced in semiconductor-doped glasses (which are commercially available as color-glass filters) or in organic solution [2][3][4]. The linear absorption of such samples generally shows a correlation with the average NC size, as the lowest absorption feature shifts towards higher energies with decreasing size [3,[5][6][7][8][9][10][11]. While this clear sign of size quantization is easily observed, the absorption spectra of semiconductordoped glasses usually fail to show sharp exciton peaks (in contrast with two-dimensional quantum wells) or even wellseparated absorption lines that reflect the expected discrete energy spectrum of a "zero-dimensional" structure. It is commonly accepted that the presence of discrete electronic states is masked in the linear absorption by strong homogeneous and inhomogeneous broadening. The nanocrystals may vary in size, geometry, and chemical composition. These variations cause a strong inhomogeneous broadening of the optical transitions. Variations of the NC size are typically on the order of 25% [12]. This value may be reduced to a few percent by sophisticated preparation techniques, but even then the size distribution has a significant influence on the optical properties [4,10,1...

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Section: Time Dependencementioning

confidence: 83%

Ultrafast dynamics of carrier-induced absorption changes in highly-excited CdSe nanocrystals

et al. 1996

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“…However, a decrease in the free-carrier decay time within the fast picosecond regime has also been observed with increasing intensity : Yao et al [39] At high excitation intensities and sufficiently high temperatures, Auger recombination, where the electron-hole recombination energy is transferred to a free electron or hole instead of being emitted as a photon, can also reduce the decay lifetime (dN/dtocN 3 where N is the free-carrier density) . Several groups have claimed to observe a reduction in the free-carrier recombination lifetime induced by Auger recombination in doped glasses [26,47,48] . However, Auger recombination has been found to be negligible in large-gap semiconductors where E g >0 .…”

Section: 4 Intensity-dependent Decaymentioning

confidence: 99%

Optical Nonlinearities and Ultrafast Carrier Dynamics in Semiconductor Doped Glasses

Williams

Olbright

Fluegel

et al. 1988

Journal of Modern Optics

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The linear and nonlinear optical properties of commercially available CdS.,Se l _ x doped glasses are reviewed and the origin, magnitude, and temporal response of the nonlinearities are discussed . The room-temperature carrier dynamics are analysed using femtosecond interband pump-probe measurements . Our experimental results show the evolution of the carriers into a hot, quasi-thermal plasma distribution via electron-electron and electron-phonon scattering . The quasi-thermal distribution cools to the lattice temperature in about 750 fs filling the states just above the band-edge . This band-filling nonlinearity is seen as the bleaching of the absorption above the bandedge . The carrier recombination lifetime is measured to be =10 ps at higher carrier densities . IntroductionIn this paper, we review the optical nonlinearities of composite semiconductor/ host materials that are composed of a fractional volume percentage of small semiconductor particles embedded in an insulating dielectric host . The semiconductor microcrystallites are smaller in size than an optical wavelength so that the composite material appears optically homogeneous . Examples of such composite materials are silicate glasses doped with semiconductor microcrystallites or semiconductor colloids [50][51][52][53][54][55][56][57][58][59][60] . Since these composite materials are macroscopically isotropic, second-order nonlinearities are usually non-existent, and technical interest focuses on their third-order nonlinearities which are essential for applications in optical signal processing . This paper addresses the dynamics of the bandfilling nonlinearity in commercially available borosilicate glasses doped with CdSxSel _ x microcrystallites of 100 to 1000A .

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confidence: 94%

“…In contrast to the developed understanding of Auger relaxation in bulk materials, its mechanism in colloidal quantum dots (CQDs) is less clear. Following the first observations of fluence-dependent exciton lifetimes in nanocrystal-doped glasses, , this dynamical signature was attributed to the Auger ionization of a trion . The majority of CQDs have displayed R –3 scaling of the Auger rate and a strong similarity between the Auger rates for very different materials of the same particle size. , The scaling has been attributed to the combined effects of the density of states and modified Coulomb couplings for hot carriers, but there has been no theoretical explanation for the similarity of observed Auger rates in vastly different materials.…”

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confidence: 99%

Auger Suppression in n-Type HgSe Colloidal Quantum Dots

Melnychuk

Guyot‐Sionnest

2019

ACS Nano

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Transient infrared photoluminescence upconversion is used to study the exciton dynamics in small-gap HgSe colloidal quantum dots in the 2000−6500 cm −1 (0.25−0.80 eV) range. The intraband mid-infrared photoluminescence decays show absent or greatly reduced Auger relaxation of biexcitons, proposed as a generic feature of weakly n-type quantum dots due to the sparse density of states in the conduction band. The nonradiative relaxation of the intraband carriers is instead consistent with near-field energy transfer to molecular vibrations of the surface ligands. In contrast, the interband near-infrared photoluminescence decays exhibit the typical distinct exciton and biexciton lifetimes with Auger coefficients comparable to other similarly sized quantum dots. Also observed are spectral and dynamical evidence of fine structure in the intraband transitions consistent with spin−orbit splitting of the electron P levels, and the emergence of plasmonic resonances in large particles.

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Evidence of strong Auger recombination in semiconductor-doped glasses

Abstract: Plasmonic coupling effect between two gold nanospheres for efficient second-harmonic generation

Cited by 63 publications

References 13 publications

Ultrafast dynamics of carrier-induced absorption changes in highly-excited CdSe nanocrystals

Ultrafast dynamics of carrier-induced absorption changes in highly-excited CdSe nanocrystals

Optical Nonlinearities and Ultrafast Carrier Dynamics in Semiconductor Doped Glasses

Auger Suppression in n-Type HgSe Colloidal Quantum Dots

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