Screened Coulomb quantum kinetics for resonant femtosecond spectroscopy in semiconductors

Vu, Q. T.; Bányai, L.; Haug, H.; Camescasse, F. X.; Likforman, J.-P.; Alexandrou, Antigoni

doi:10.1103/physrevb.59.2760

Cited by 27 publications

(19 citation statements)

References 22 publications

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“…Under the present experimental conditions, electron-electron scattering dominates over electron-phonon scattering. For completeness, however, the quantum kinetics of electron-LO-phonon scattering at T 300 K is also accounted for [10,13]. In order not to overburden the numerical calculation, we describe the corresponding spectral functions, which determine the memory kernels of the scattering integrals, by a free-particle Wigner-Weisskopf approximation [14].…”

Section: Photon Echoes From Semiconductor Band-to-band Continuum Tranmentioning

confidence: 99%

Photon Echoes from Semiconductor Band-to-Band Continuum Transitions in the Regime of Coulomb Quantum Kinetics

et al. 1999

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We show that the coherent response of semiconductor band-to-band continuum transitions at room temperature, excited by 11 fs pulses at elevated carrier densities, deviates substantially from that expected for an ideal photon echo. A microscopic non-Markovian quantum kinetic theory of both electron-electron and electron-LO-phonon scattering reproduces these unusual experimental observations qualitatively and, furthermore, the famous scaling of the decay time t with carrier density n eh according to Consider a dense gas of electrons and holes generated at random places in pairs with opposite momentum in coherent quantum states in a semiconductor. It is clear that the particles will move in such a way that they screen their mutual Coulomb interaction. How long does it take that screening is built up and that scattering has destroyed the initially quantum mechanically coherent state? About one decade ago, Shank et al. addressed this fundamental question when they studied the variation of the Coulomb scattering in a dense gas of optically excited crystal electrons and holes [1,2] with density n eh using ഠ10 fs pulses and a photon echo technique. They reported that the decay time t of the photon echo signal at room temperature scales approximately according to t~n 21͞D eh , where D is the dimension of either bulk GaAs ͑D 3͒ or GaAs quantum wells ͑D 2͒. At that time, it was tempting and appealing to interpret this seemingly simple result in terms of the nearest-neighbor scattering of D-dimensional hard spheres in which case it is simple to show that the average time between different collisions scales~n 21͞D eh indeed. Today, a number of important questions are still unanswered. (i) Is it a photon echo? In analogy with a spin echo this would mean that a first short pulse excites the system, a second pulse arrives after time delay t 21 , and the coherent collective response of the system, the photon echo, peaks at yet another time delay t 21 later. Without real-time resolution [1,2], however, one only measures the energy of the echo signal versus t 21 and its decay time t. For a phenomenological dephasing time T 2 it is known that T 2 4t holds for a four-wave mixing (FWM) geometry under these conditions. Not a single experiment, however, has shown directly that the coherent real-time response of semiconductor band-to-band continuum transitions under these conditions is a photon echo indeed. Under quite different conditions (T 4 K, 100 fs pulses, and much lower carrier densities), Ref. [3] showed that the total response is not a photon echo. Only after spectral filtering (behind the sample) of those components of the FWM-signal resonant with the band-to-band continuum, were they able to isolate a contribution which corresponded to an echo. The position of this signal shifted with time delay as expected [4], its width was constant (150 fs) and given by the time resolution of their setup for all conditions. The picosecond response of inhomogeneously broadened excitonic transitions [5] as well as the response of modulation-...

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Section: Photon Echoes From Semiconductor Band-to-band Continuum Tranmentioning

confidence: 99%

Photon Echoes from Semiconductor Band-to-Band Continuum Transitions in the Regime of Coulomb Quantum Kinetics

et al. 1999

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“…15 Indirect evidence for the SO exciton has been seen in pump-continuum-probe experiments in GaAs due to conduction state energy renormalization effects, 16 although a detailed non-Markovian analysis was needed to determine the influence of the SO exciton resonance on the differential transmission spectra. 17 Here we report the observation of a clear signature of the SO exciton in a III-V semiconductor through measurement of its coherent response using spectrally resolved four-wave mixing ͑SR-FWM͒. The SO exciton response was studied in InP since the SO exciton energy in this system ͑1.532 eV at 77 K͒ is readily accessable by our tunable short pulse Ti:sapphire laser.…”

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Coherent response of spin-orbit split-off excitons in InP: Isolation of many-body effects through interference

et al. 2002

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The spin-orbit split-off ͑SO͒ exciton is observed in a III-V semiconductor ͑InP͒ using spectrally resolved four-wave mixing ͑SR-FWM͒ with 1.515 eV, 35 fs pulses at 77 K. Interference between the coherent response of the SO exciton and that of electron-hole pairs in continuum states leads to frequency-and time-dependent signatures that can be directly attributed to excitation-induced dephasing ͑EID͒ of the SO exciton. Many-body effects can therefore be isolated from free induction decay contributions, in contrast to experiments that probe the fundamental exciton. Simulations employing the multiband Boltzmann-Bloch equations including EID effects corroborate our experimental results.

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“…Low-intensity femtosecond experiments [3,4] have been successfully analyzed in terms of the quantum kinetic scattering integrals for the interaction with LO-phonons [3,5], while high-intensity experiments [6,7] can be understood primarily in terms of the quantum kinetics due to the time-dependently screened carrier±carrier interaction [8]. But in general both scattering mechanisms are involved and should be treated together in a consistent manner.…”

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“…the LO-phonons at low densities and the plasmons at high densities) has for small momentum transfer always a larger oscillator strength in comparison with the lower branch. This effective interaction will be used to review the analysis of resonant femtosecond DTS [7] and FWM [6] experiments. In particular recent resonant FWM experiments with coherent control [16] allow to detect weak oscillations of the integrated FWM signal with a period of the mixed phonon±plasmon modes [17].…”

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Coulomb Quantum Kinetics for Semiconductor Femtosecond Spectroscopy

Haug

2000

phys. stat. sol. (b)

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Screened Coulomb quantum kinetics for resonant femtosecond spectroscopy in semiconductors

Cited by 27 publications

References 22 publications

Photon Echoes from Semiconductor Band-to-Band Continuum Transitions in the Regime of Coulomb Quantum Kinetics

Photon Echoes from Semiconductor Band-to-Band Continuum Transitions in the Regime of Coulomb Quantum Kinetics

Coherent response of spin-orbit split-off excitons in InP: Isolation of many-body effects through interference

Coulomb Quantum Kinetics for Semiconductor Femtosecond Spectroscopy

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