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29 April 1999 Carrier dynamics and THz radiation in biased semiconductor structures
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When a biased semiconductor is excited by femtosecond laser pulses, it generated terahertz radiation. The rapid change in the transport photocurrent, due to the ultrafast excitation of the carrier by laser pulses and biased electric fields, generate terahertz electromagnetic pulses. The change in the photocurrent arises from two processes: acceleration of the photogenerated carries under an electric field, and a rapid change in carrier density. These two processes contribute to the generation of the terahertz radiation. Our calculations show that the main part of the terahertz radiation result from the ultrafast change of the carrier density. We consider the terahertz radiation from biased photoconductive antennas pumped by femtosecond laser pulses. The calculations are based on the Drude-Lorentz theory of the carrier transport in semiconductors. Our calculations model includes the interaction between electrons and holes, trapping of carriers in mid-gap states, scattering of carries, and dynamical space-charge effects. Our calculations show that the local electric field will oscillate and induce electromagnetic radiation at high carrier generation density.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Zhi-Sheng Piao, Masahiko Tani, and Kiyomi Sakai "Carrier dynamics and THz radiation in biased semiconductor structures", Proc. SPIE 3617, Terahertz Spectroscopy and Applications, (29 April 1999);

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