Using Optically Pumped Thz Pulse Detection Technology In Semiconductor Ultrafast Carrier Dynamics

In this thesis, the ultrafast carrier dynamics of n-Si , p-Si and SI-GaAs have been investigated by the optical-pump terahertz-probe spectroscopy (OPTP). The n-Si and p-Si are also investigated by the terahertz time-domain spectroscopy (THz-TDS). The reflective index, relative permittivity, complex conductivity and dielectric loss of n-Si and p-Si are calculated in the range of 0.5~2.0 THz, and the results indicate that two samples both have good dielectric properties and can be used to work in the THz range. In the OPTP experiment, it's found that the terahertz transmission which is relevant to photoconductivity of sample decreased with the increased pump power in the same sample. If a electric field is applied to the GaAs surface in plane when the sample is excited by a 800nm fs laser pulse, the carrier intervalley scattering occurs in SI-GaAs. And the terahertz transmission could be modulated by the applied electric field when the semi-insulating GaAs (SI-GaAs) is under photoexcited state. Finally, we extract the photo-generated carrier density, effective carrier mobility and collision time from the Drude-Smith model which fits well to the experimental data.