Ultrafast high-field carrier transport in GaAs measured by femtosecond pump-terahertz probe spectroscopy

摘要

Femtosecond pump-terahertz probe studies of carrier dynamics in semi-insulating GaAs have been investigated in detail for various pump powers and at electric fields up to 15 kV/cm. The pump-induced attenuation of terahertz transmission reduces obviously at high field, and the carrier relaxation time is also found to be correlated with photoinjected carrier density and electric field. These effects can be fully explained in terms of the carrier intervalley scattering and the surface states filling in GaAs, which may influence the carrier recombination process. Moreover, the carrier screening effect at high pump powers is also discussed.