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Proceedings Paper

Ultrafast dynamics of photoexcited charge and spin currents in semiconductor nanostructures
Author(s): Torsten Meier; Bernhard Pasenow; Huynh Thanh Duc; Quang Tuyen Vu; Hartmut Haug; Stephan W. Koch
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Paper Abstract

Employing the quantum interference among one- and two-photon excitations induced by ultrashort two-color laser pulses it is possible to generate charge and spin currents in semiconductors and semiconductor nanostructures on femtosecond time scales. Here, it is reviewed how the excitation process and the dynamics of such photocurrents can be described on the basis of a microscopic many-body theory. Numerical solutions of the semiconductor Bloch equations (SBE) provide a detailed description of the time-dependent material excitations. Applied to the case of photocurrents, numerical solutions of the SBE for a two-band model including many-body correlations on the second-Born Markov level predict an enhanced damping of the spin current relative to that of the charge current. Interesting effects are obtained when the scattering processes are computed beyond the Markovian limit. Whereas the overall decay of the currents is basically correctly described already within the Markov approximation, quantum-kinetic calculations show that memory effects may lead to additional oscillatory signatures in the current transients. When transitions to coupled heavy- and light-hole valence bands are incorporated into the SBE, additional charge and spin currents, which are not described by the two-band model, appear.

Paper Details

Date Published: 8 February 2007
PDF: 14 pages
Proc. SPIE 6471, Ultrafast Phenomena in Semiconductors and Nanostructure Materials XI and Semiconductor Photodetectors IV, 647108 (8 February 2007);
Show Author Affiliations
Torsten Meier, Philipps Univ. (Germany)
Bernhard Pasenow, Philipps Univ. (Germany)
Huynh Thanh Duc, Philipps Univ. (Germany)
Ho Chi Minh City Institute of Physics (Vietnam)
Quang Tuyen Vu, Philipps Univ. (Germany)
Univ. of Natural Sciences (Vietnam)
Hartmut Haug, Johann Wolfgang Goethe-Univ. Frankfurt (Germany)
Stephan W. Koch, Philipps Univ. (Germany)

Published in SPIE Proceedings Vol. 6471:
Ultrafast Phenomena in Semiconductors and Nanostructure Materials XI and Semiconductor Photodetectors IV
Marshall J. Cohen; Kong-Thon Tsen; Joseph P. Estrera; Jin-Joo Song, Editor(s)

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