Ultrafast Dynamics of Optically-Induced Charge and Spin Currents in Semiconductors

Meier, Torsten; Duc, Huynh Thanh; Vu, Quang Tuyen; Pasenow, B.; Hübner, Jens; Chatteryee, Sangam; Rühle, W. W.; Haug, H.; Koch, S. W.

doi:10.1007/978-3-540-38235-5_15

Cited by 4 publications

(3 citation statements)

References 26 publications

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“…This process works in centrosymmetric and noncentrosymmetric materials. For semiconductor nanostructures, a microscopic theory has been developed that provides a detailed description of the ultrafast dynamics of the optical excitations and the photocurrents including many-body effects and scattering processes [26][27][28]. This approach is based on the semiconductor Bloch equations [29] which are extended by the electric field induced intraband acceleration [26,30].…”

Section: Resultsmentioning

confidence: 99%

Generation and time‐resolved detection of coherently controlled electric currents at surfaces

Güdde

Rohleder

Meier

et al. 2009

Phys. Status Solidi (c)

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We demonstrate a technique for the generation and detection of electron currents at surfaces on a femtosecond time scale with a contact‐free experimental setup based on a combination of coherent control and photoemission spectroscopy. We have applied this technique for electrons excited into image‐potential states on a Cu(100) surface that form a free‐electron‐like band in the direction parallel to the surface. The photogeneration of currents is described by optical Bloch equations for a multiband model. By incorporating field‐induced interband and intersubband transitions together with intraband accelerations into the model, the observed phase dependence of the population and of the current can be reproduced. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Resultsmentioning

confidence: 99%

Generation and time‐resolved detection of coherently controlled electric currents at surfaces

Güdde

Rohleder

Meier

et al. 2009

Phys. Status Solidi (c)

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“…21,23,24 This approach is based on the semiconductor Bloch equations 25 which are extended by the electric field induced intraband acceleration. 20,23 This theory, however, cannot be directly applied for the description of photoexcited electron currents at metal surfaces where the electronic structure as well as the decay processes of excited electrons are different compared to bulk semiconductors.…”

Section: Modeling Of the Coherent Excitationmentioning

confidence: 99%

Ultrafast coherent control of electric currents at metal surfaces

et al. 2010

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We report the development of an experimental technique to measure the dynamics of electrical currents on the femtosecond timescale. The technique combines methods of coherent control with time-and angle-resolved photoelectron spectroscopy. Direct snapshots of the momentum distribution of the excited electrons as function of time are then determined by photoelectron spectroscopy. In this way we gain information on the generation and decay of ultrashort current pulses in unprecedented detail. In particular, this technique allows the observation of elastic electron scattering in terms of an incoherent population dynamics in momentum space. We have applied this optical current generation and detection scheme to electrons in so-called image-potential states which represent a prototype of two-dimensional electronic surface states. Electrons in these states are bound perpendicular to the metal surface by the Coulombic image potential whereas they can move almost freely parallel to the surface. For the (n=1) image-potential state of Cu(100) we find a decay time of 10 fs due to electron scattering with steps and surface defects.

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“…For semiconductor nanostructures, a microscopic theory has been developed that provides a detailed description of the ultrafast dynamics of the optical generation and the decay of photocurrents including many-body effects and scattering processes [23][24][25]. This approach is based on the semiconductor Bloch equations [26] that are extended by the electric field induced intraband acceleration [22,24].…”

Section: Modeling Of the Coherent Excitationmentioning

confidence: 99%

Coherently Controlled Electrical Currents at Surfaces

Güdde

Rohleder

Meier

et al. 2010

Dynamics at Solid State Surfaces and Interfaces

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During the last decade, great progress has been made by investigating electron transport through single molecules, metallic point contacts, or chains of single atoms by using scanning tunneling microscopy or break junctions [1,2]. Many of these works have focused on the coherent regime where inelastic scattering of the electrons due to vibronic or electronic excitation within the junction can be neglected. In this regime, nanoscale wires show no ohmic behavior and a quantization of the conductance has been observed as can be described by the Landauer theory [3]. While these experiments observe electron transport on the atomic scale, information about the dynamics of electron transport on the timescale of the relevant scattering mechanisms is scarce. The microscopic understanding of the mechanisms of electron transport, however, is not only of great interest for the development of new small-scale electronic devices, the connection of the electric conductivity s of a material with the microscopic scattering processes of individual charge carriers is also a fundamental issue, central to solid state physics [4]. This question goes back to Paul Drude [5] who has connected the electric conductivity s of a metal to an empirical scattering time t of free electrons that are accelerated in an external electric field, resulting in the well known Drude formula s ¼ e 2 n e t=m e , where e, m e , and n e are the electron charge, mass and density, respectively. Even if this model is oversimplified as it does not consider the quantum nature and the many-body aspects of electronelectron interaction, it gives the correct order of magnitude for the timescale of electron scattering processes. For Cu at room temperature, for example, it gives a scattering time of 27 fs [4], which shows that usual conductivity measurements cannot resolve the individual scattering events because available electronic equipment can neither produce trigger signals nor detect transients that are shorter than tens of picoseconds.Recently, we have introduced a new experimental technique that is capable of accessing the dynamics of electrical currents on the femtosecond timescale [6]. This contact-free technique combines the pure optical generation of electric

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Ultrafast Dynamics of Optically-Induced Charge and Spin Currents in Semiconductors

Cited by 4 publications

References 26 publications

Generation and time‐resolved detection of coherently controlled electric currents at surfaces

Generation and time‐resolved detection of coherently controlled electric currents at surfaces

Ultrafast coherent control of electric currents at metal surfaces

Coherently Controlled Electrical Currents at Surfaces

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