Photoelectric Characteristics of GaAs and LT-GaAs Studied by OPTP Spectroscopy

In this paper, the photoelectric characteristics of intrinsic gallium arsenide (GaAs) and low-temperature grown gallium arsenide (LT-GaAs) have been studied by the optical-pump terahertz-probe (OPTP) spectroscopy. Under the optical excitation with same energy density, GaAs shows higher photoconductivity and longer carrier relaxation time than LT-GaAs. The experimental results show that the carrier relaxation time of the LT-GaAs increases with the increase of excitation energy density. The fitting results of the carrier relaxation process show that the lifetime of photogenerated carrier in LT-GaAs is related to the concentration of internal defects. Finally, the frequency-dependent parameters in these two materials have been fitted by the Drude-Smith model.