Time-resolved direct observation of Auger recombination in semiconductor-doped glasses

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

doi:10.1063/1.98499

Cited by 72 publications

(26 citation statements)

References 11 publications

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“…It is speculated that the heat generated by this multiphonon decay induces local structural changes [90] that can anneal or eliminate the trap states, and create additional `dangling-bond' surface states [91] . Therefore, after extended laser exposure, fewer trap states and more surface states exist, carriers decay through the accumulated surface states before they can decay into the few remaining trap states, quantum efficiency decreases [47], and the slow decay is suppressed . We have observed an increase in the absorption of quantumdot-doped glasses after extended laser exposure .…”

Section: Trapped-carrier Decay Suppressionmentioning

confidence: 98%

“…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%

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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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Section: Trapped-carrier Decay Suppressionmentioning

confidence: 98%

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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“…One of the most important features of QDs is the band‐gap energy shift by their strong quantum confinement effects that has been clarified by the pioneering works in various types of semiconductor nanocrystals . It was also clarified that the quantum confinement effects cause efficient many‐body interaction, e.g., nonradiative Auger recombination . After that, through a lot of progresses in their size and composition control, the band‐gap tuning becomes more and more accurate and extends to the whole visible spectral range .…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10][11] It was also clarified that the quantum confinement effects cause efficient many-body interaction, e.g., nonradiative Auger recombination. [12][13][14] After that, through a lot of progresses in their size and composition control, the band-gap tuning becomes more and more accurate and extends to the whole visible spectral range. [15][16][17] Moreover, QD structures suppressing Auger recombination were investigated.…”

Section: Introductionmentioning

confidence: 99%

Coherent Spectroscopy of Multiple Excitons in Colloidal Nanocrystal Quantum Dots

Tahara

Kanemitsu

2019

ChemNanoMat

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Over three decades of intense research on colloidal semiconductor nanocrystal quantum dots (QDs) have passed, and the multitude of physical effects in QD systems still makes fascinating discoveries even today. In particular, the use of multiple excitons and their coherence is a hot topic to be investigated. We explore the potential of colloidal QDs for next‐generation optoelectronic applications. Here, we summarize our recent studies on the multiple‐exciton harmonic quantum coherence in PbS QDs. The multiple excitonic coherence can be observed with our newly developed system for phase‐locked interference detection of transient absorption signals. We found that multiple excitons exhibit dipole oscillations with integer multiples of the exciton resonance frequency. An important practical feature of this harmonic quantum coherence of multiple excitons is that it assists photoabsorption processes. Therefore, harmonic quantum coherence is a key to realize advanced optoelectronic applications.

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“…However, the decay time of the former is shorter than that of the latter. The difference in the decay times between the transient absorption and the DFWM is considered to be due to photodarkening and Auger effect [10]. Since photon energy of pump light (2.57 eV) is higher than band-gap energy of semiconductor (1.85 eV) in R-68, high density of carriers are generated by one-photon absorption for the transient absorption experiment.…”

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confidence: 99%

Ultrafast dynamics in CdSSe-doped glasses

Miyoshi

Fukuda

Ebina

et al. 2004

Journal of Materials Science

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1There has been considerable interest in nonlinear optical properties of semiconductor-doped glasses, since they have large optical nonlinearity with a fast response time [1]. In recent years attention has been given to below-band-gap nonlinearities of semiconductor-doped glasses [2,3]. Although the value of the optical nonlinearity is rather small, the response time can be very fast. In this letter, we report femtosecond dynamics in semiconductor-doped glasses below the band gap.The samples investigated were commercial CdSSe-doped filter glasses: Asahi R-64, R-66; Hoya R-64, R-66, R-68; Schott RG645, RG665; and Corning 2-58 and 2-64. CdS-doped glass L-42 and undoped glass Y-0 were also investigated for comparison. Thickness of samples was approximately 2.5 mm. The concentration of CdSSe was approximately 0.4 wt% [4]. Sizes of CdSe nanocrystals were around 8 to 30nm [4]. The degenerate four-wave mixing (DFWM) experiments were performed with a Ti:sapphire laser and a regenerative amplifier (Spectra Physics Tsunami and Spitfire; wavelength = 780 nm, pulse duration = 130 fs, peak power density = 0.5 -1 TW/cm 2 , repletion rate = 1 kHz) using a boxcar configuration at 300 K.The laser beam was divided into three parts: two pump beams and a probe beam. All beams were polarized in the same direction. Pump and probe beams were focused by a single lens on the surface of the sample.The peak power density of pump light was approximately 0.2 TW/cm 2 , and that of probe light was 0.03 TW/cm 2 . The time delay between the pump pulses and the probe pulse was adjusted by an optical delay line. Transient absorption in the infrared range was measured using pump and probe technique. Pump and probe pulses were delivered from optical parametric oscillators. The peak power density of pump light was 0.75 TW/cm 2 . Wavelength of pump light was 482 nm, and that of probe light was 3 m. DFWM signal was observed in all glasses investigated. Fig. 1 shows dynamics of DFWM signal for Asahi Y-0, L-42 and R-64. There are two contributions to the DFWM signal. The fast contribution is observed in all glasses investigated. The profile of the fast contribution as a function of the time delay between pump and probe pulses follows closely that of the laser pulse. Note that the fast contribution is observed in glass without semiconductor (Y-0). Since signal intensity of the fast contribution in the undoped glass is the same as those in the doped glasses, the fast contribution is attributable to glass matrix.It is reported that the intensity of nearly degenerate frequency mixing signal in BK7 glass, which does not contain semiconductor, is comparable with those of CdSSe-doped glasses [3]. The nonlinearity of the glass is mainly due to electronic polarization of bound electrons.The slow contribution is observed in glasses with longer cut-off wavelength: R-64, R-66 etc. Fig. 2 shows dynamics of DFWM signal for Asahi R-64 and Hoya R-68. The decay time of the slow contribution 2 is approximately 4 ps for Asahi R-64 and 6 ps for Hoya R-68. Other samples als...

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Time-resolved direct observation of Auger recombination in semiconductor-doped glasses

Abstract: Using time-resolved techniques, absorption recovery, and degenerate four-wave mixing, we directly observe the nonexponential intensity-dependent recombination of free carriers photoexcited in semiconductor-doped glasses. We assign this behavior to Auger recombination.

Cited by 72 publications

References 11 publications

Optical Nonlinearities and Ultrafast Carrier Dynamics in Semiconductor Doped Glasses

Optical Nonlinearities and Ultrafast Carrier Dynamics in Semiconductor Doped Glasses

Coherent Spectroscopy of Multiple Excitons in Colloidal Nanocrystal Quantum Dots

Ultrafast dynamics in CdSSe-doped glasses

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