Optical detection of folded mini-zone-edge coherent acoustic modes in a doped GaAs/AlAs superlattice

Beardsley, R.; Akimov, A. V.; Glavin, B. A.; Maryam, W.; Henini, M.; Kent, A. J.

doi:10.1103/physrevb.82.041302

Cited by 7 publications

(12 citation statements)

References 18 publications

(29 reference statements)

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“…The acoustic-mode coherent vibration of the lattice causes modulation of the reflection, with a frequency determined by the phonon energy. [43][44][45][46][47][48][49][50][51][52][53][54][55][56] The frequency corresponds to an energy of 0.14 meV. Unlike in other materials where many periods of oscillation are usually observed, [43][44][45][46][47][48][49][50][51][52][53][54][55][56] only one to two periods are observed here.…”

Section: Coherent Acoustic Phononsmentioning

confidence: 52%

Spatially resolved femtosecond pump-probe study of topological insulator Bi2Se3

et al. 2011

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Carrier and phonon dynamics in Bi 2 Se 3 crystals are studied by a spatially resolved ultrafast pump-probe technique. Pronounced oscillations in differential reflection are observed with two distinct frequencies and are attributed to coherent optical and acoustic phonons, respectively. The rising time of the signal indicates that the thermalization and energy relaxation of hot carriers are both sub-ps in this material. We found that the thermalization and relaxation time decreases with the carrier density. The expansion of the differential reflection profile allows us to estimate an ambipolar carrier diffusion coefficient on the order of 500 cm 2 /s. A long-term slow expansion of the profile shows a thermal diffusion coefficient of 1.2 cm 2 /s.

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Section: Coherent Acoustic Phononsmentioning

confidence: 52%

Spatially resolved femtosecond pump-probe study of topological insulator Bi2Se3

et al. 2011

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“…This gradual transition from real to virtual excitation has strong consequences regarding the selectivity of the optically generated coherent phonons. 13,[23][24][25] This conceptually explains the abrupt sign change of the electronic contribution to DR=R observed between 150 K and 100 K [see Fig. 3(a)], and the change in the acoustic components in Fig.…”

Section: -3mentioning

confidence: 68%

“…1(c)], are completely absent at low temperatures, and appear abruptly when increasing Tտ150 K. This appearance is attributed to a symmetry breakdown related to the resonance effects together with the effects of the doping of some of the constituting layers, which make these modes active. 25 As an example, the spectral amplitude of one of the BZE-modes, the one at 242 GHz, is shown additionally in Fig. 4(d) (empty stars).…”

Section: -3mentioning

confidence: 99%

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Investigation of coherent acoustic phonons in terahertz quantum cascade laser structures using femtosecond pump-probe spectroscopy

Bruchhausen¹,

Lloyd‐Hughes²,

Hettich³

et al. 2012

Journal of Applied Physics

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The dynamics of acoustic vibrations in terahertz quantum cascade laser structures (THz-QCLs) is studied by means of femtosecond pump-probe spectroscopy. The phonon modes are characterized by the folding of the acoustic dispersion into an effective reduced Brillouin zone. An accurate identification of this dispersion allows the sample structure and periodicity to be determined with high precision on the order of 0.1%. By temperature tuning the energy of the electronic levels of the system and performing wavelength dependent measurements, we are able to study the impulsive resonant generation and detection of coherent acoustic phonon modes. These results are supported by simulations of the electronic system that well explain the experimental observations. The effects of interface (IF) roughness on coherent acoustic phonon spectra are clearly observed for equal nominal THz-QCL structures but with different interface qualities.

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“…Our measured decay rates for a variety of transitions, and those previously measured for P and As [4,15], seem to scale simply with the phonon density of states, consistent with direct phonon relaxation to the ground state. In addition, these decay rates lead us to speculate that engineering the phonon density of states in nanostructures [21] offers the possibility of making the excited-state lifetimes much longer, with a maximum then determined by the radiative lifetime which is theoretically in the ns-s range.…”

Section: Introductionmentioning

confidence: 97%

Time-Resolved Dynamics of Shallow Acceptor Transitions in Silicon

et al. 2013

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Shallow group-V donors in silicon may be thought of as hydrogenlike, and shallow acceptors are similarly described by effective-mass theory with similar energy scales, which implies that donor and acceptor excitations should be just as long-lived. Yet, spectral widths of acceptors are considerably wider. We have measured the orbital dynamics of acceptors in silicon using time-domain spectroscopy with a free-electron laser. Both the population and coherence lifetimes for acceptors in natural silicon are substantially longer-e.g. approximately 60 ps for boron-than implied by the spectral linewidths; our experiments also establish the recombination time for ionized acceptors to be, at approximately 500 ps, nearly an order of magnitude longer. We show that there are no extra sources of decoherence introduced by the host crystal, other than the population relaxation. In this sense, the crystal acts as an atom trap, and, by introducing quantum coherent control of acceptors to that previously established for donors, we open the way to optically controllable nanoscale p-n devices.

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Optical detection of folded mini-zone-edge coherent acoustic modes in a doped GaAs/AlAs superlattice

Cited by 7 publications

References 18 publications

Spatially resolved femtosecond pump-probe study of topological insulator Bi2Se3

Spatially resolved femtosecond pump-probe study of topological insulator Bi2Se3

Investigation of coherent acoustic phonons in terahertz quantum cascade laser structures using femtosecond pump-probe spectroscopy

Time-Resolved Dynamics of Shallow Acceptor Transitions in Silicon

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