An analytical model describing the dynamics of photoelectrons excited by femtosecond optical pulses in an AlGaAs/GaAs p-i-n diode is presented. A change in the reverse bias causes a change in the terahertz generation mechanism. The waveform of the photocurrent (amplitude, duration, maximum position) depends significantly on both the reverse bias and the level of optical excitation, as well as on the energy of the laser radiation quantum. At sufficiently high values of the internal electric field strength, terahertz generation in a heterostructure p-i-n diode is caused by the acceleration of electrons over several hundred femtoseconds to a velocity significantly exceeding the saturation velocity ("velocity overshoot"), followed by a sharp drop associated with the transition of electrons from the central valley to the side valleys. Keywords: terahertz electromagnetic radiation, p-i-n diode, femtosecond laser excitation, photoelectron dynamics.

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Дата начала обработки статистических данных - 27 января 2016 г.