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Carrier dynamics of terahertz emission from low-temperature-grown gaas.

Through theoretical modeling, we find that the dynamics of photogenerated carriers play a very important role in shaping the temporal waveform of terahertz (THz) radiation pulses emitted from biased low-temperature (LT-grown GaAs antenna. Our modeling gives successful analyses for the sharp and short, slow and long negative parts of temporal THz waveforms. By including intraband, carrier relaxation effect in the modeled mobility, we find an obvious dependence of the THz conversion efficiency on the material of THz emitter and experimental parameters such as the optical duration, the center wavelength, and the fluence of the laser pulses. Our research also shows that electron-hole and electron-electron collisions in LT-GaAs contribute to the saturation phenomenon with an increase of laser fluence.