Transient carrier and field dynamics in quantum-well parallel transport: From the ballistic to the quasi-equilibrium regime

Sha, Wei E. I.; Rhee, June-Koo Kevin; Norris, T. B.; Schaff, William J.

doi:10.1109/3.159551

Cited by 47 publications

(26 citation statements)

References 42 publications

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“…resolving studies on electron propagation in condensed matter employed laser-based spectroscopic techniques to reveal ballistic currents and drift motion of charge carriers [6][7][8][9] .…”

mentioning

confidence: 99%

Direct observation of electron propagation and dielectric screening on the atomic length scale

Neppl

Ernstorfer

Cavalieri

et al. 2015

Nature

165

148

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The propagation and transport of electrons in crystals is a fundamental process pertaining to the functioning of most electronic devices. Microscopic theories describe this phenomenon as being based on the motion of Bloch wave packets. These wave packets are superpositions of individual Bloch states with the group velocity determined by the dispersion of the electronic band structure near the central wavevector in momentum space. This concept has been verified experimentally in artificial superlattices by the observation of Bloch oscillations—periodic oscillations of electrons in real and momentum space. Here we present a direct observation of electron wave packet motion in a real-space and real-time experiment, on length and time scales shorter than the Bloch oscillation amplitude and period. We show that attosecond metrology (1 as = 10^-18 seconds) now enables quantitative insight into weakly disturbed electron wave packet propagation on the atomic length scale without being hampered by scattering effects, which inevitably occur over macroscopic propagation length scales. We use sub-femtosecond (less than 10^-15 seconds) extreme-ultraviolet light pulses to launch photoelectron wave packets inside a tungsten crystal that is covered by magnesium films of varied, well-defined thicknesses of a few ångströms. Probing the moment of arrival of the wave packets at the surface with attosecond precision reveals free-electron-like, ballistic propagation behaviour inside the magnesium adlayer—constituting the semi-classical limit of Bloch wave packet motion. Real-time access to electron transport through atomic layers and interfaces promises unprecedented insight into phenomena that may enable the scaling of electronic and photonic circuits to atomic dimensions. In addition, this experiment allows us to determine the penetration depth of electrical fields at optical frequencies at solid interfaces on the atomic scal

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“…resolving studies on electron propagation in condensed matter employed laser-based spectroscopic techniques to reveal ballistic currents and drift motion of charge carriers [6][7][8][9] .…”

mentioning

confidence: 99%

Direct observation of electron propagation and dielectric screening on the atomic length scale

Neppl

Ernstorfer

Cavalieri

et al. 2015

Nature

165

148

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“…In principle, the saturation at high optical power densities could result either from screening of the bias field due to the space-charge field or due to the radiation field itself. Saturation studies of dipole antennas and related structures have focused on space charge screening, which has led to significant saturation on an ultrafast time scale at carrier densities in the 10 -10 cm range [41], [42]. In our highest power (44 mW) single-pulse experiments, the estimated carrier density is 3 10 cm .…”

Section: Overcoming Saturation Of Terahertz Radiationmentioning

confidence: 94%

“…Saturation has been observed in a number of different transmitter structures [12], [20], [40]- [42]. In principle, the saturation at high optical power densities could result either from screening of the bias field due to the space-charge field or due to the radiation field itself.…”

Section: Overcoming Saturation Of Terahertz Radiationmentioning

confidence: 99%

Terahertz waveform synthesis via optical pulse shaping

Liu

Park

Weiner

1996

IEEE J. Select. Topics Quantum Electron.

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Abstract-We describe the principles of free-space terahertz waveform synthesis by using a programmable optical pulse shaper to drive a photoconducting dipole antenna. We illustrate this technique using several experimental examples, including manipulation of the amplitude and the phase of ultrafast terahertz waveforms as well as generation of ultrafast bit sequences at terahertz frequencies. We present a theory which accurately predicts the shapes of the terahertz waveforms produced in our experiments. In addition to the controllability of terahertz radiation, we have shown that optical pulse shaping can be used to avoid saturation of the terahertz field at highpeak power and increase generation efficiencies for terahertz radiations at selected, narrow-band frequencies.

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“…11,12 Therefore, the dipole charge created by the spatially separating electron and hole clouds cannot exceed this stored charge for times shorter than the RC-time constant of the external circuit. In fact, this is expected to be the case in our experiments.…”

Section: ͓S0003-6951͑97͒02601-6͔mentioning

confidence: 99%

Femtosecond differential transmission measurements on low temperature GaAs metal–semiconductor–metal structures

Keil

Hvam

Tautz

et al. 1997

Applied Physics Letters

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We report on differential transmission measurements on low temperature grown (LT)-GaAs with and without applied electrical fields at different wavelengths. Electrical fields up to 100 kV/cm can be applied via an interdigitated contact structure to our LT GaAs samples which have been removed from the substrate by epitaxial lift off. In the presence of an electric field, both, the absorption bleaching due to phase space filling and field induced absorption changes due to the Franz–Keldysh effect contribute to the transmission changes. We observe an extended carrier lifetime with applied field. The response time of a biased metal–semiconductor–metal detector, therefore, exceeds the carrier life time of the substrate material.

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Transient carrier and field dynamics in quantum-well parallel transport: From the ballistic to the quasi-equilibrium regime

Cited by 47 publications

References 42 publications

Direct observation of electron propagation and dielectric screening on the atomic length scale

Direct observation of electron propagation and dielectric screening on the atomic length scale

Terahertz waveform synthesis via optical pulse shaping

Femtosecond differential transmission measurements on low temperature GaAs metal–semiconductor–metal structures

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