Transient photoconductivity in GaAs as measured by time-resolved terahertz spectroscopy
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- 15 December 2000
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 62 (23), 15764-15777
- https://doi.org/10.1103/physrevb.62.15764
Abstract
The onset and decay of photoconductivity in bulk GaAs has been measured with 200-fs temporal resolution using time-resolved THz spectroscopy. A low carrier density with less than 100-meV kinetic energy was generated via photoexcitation. The conductivity was monitored in a noncontact fashion through absorption of THz (far-infrared) pulses of several hundred femtosecond duration. The complex-valued conductivity rises nonmonotonically, and displays nearly Drude-like behavior within 3 ps. The electron mobilities obtained from fitting the data to a modified Drude model at room temperature with and at 70 K with are in good agreement with literature values. There are, however, deviations from Drude-like behavior at the shortest delay times. It is shown that a scalar value for the conductivity will not suffice, and that it is necessary to determine the time-resolved, frequency-dependent conductivity. From 0 to 3 ps a shift to higher mobilities is observed as the electrons relax in the valley due to LO-phonon-assisted intravalley absorption. At long delay times (5–900 ps), the carrier density decreases due to bulk and surface recombination. The time constant for the bulk recombination is 2.1 ns, and the surface recombination velocity is
Keywords
This publication has 63 references indexed in Scilit:
- Probing ultrafast carrier and phonon dynamics in semiconductorsJournal of Applied Physics, 1998
- Femtosecond Carrier Dynamics in GaAs Far from EquilibriumPhysical Review Letters, 1996
- Ultrafast Spectroscopy of Semiconductors and Semiconductor NanostructuresPublished by Springer Science and Business Media LLC ,1996
- Subpicosecond thermalization and relaxation of highly photoexcited electrons and holes in intrinsic andp-type GaAs and InPPhysical Review B, 1993
- Femtosecond tunable nonlinear absorption spectroscopy inAsPhysical Review B, 1993
- Coulomb enhancement of above-band-gap pump-continuum probe spectroscopyPhysical Review B, 1993
- Picosecond electro-optic sampling of electron-hole vertical transport in surface space charge fieldsChemical Physics Letters, 1989
- Femtosecond intervalley scattering in GaAsApplied Physics Letters, 1988
- Ultrafast relaxation dynamics of photoexcited carriers in GaAs and related compoundsJournal of the Optical Society of America B, 1985
- Femtosecond Orientational Relaxation of Photoexcited Carriers in GaAsPhysical Review Letters, 1984