Exotic transport regime in GaAs: absence of intervalley scattering leading to quasi-ballistic, real-space THz oscillations
Monte Carlo simulations show that electrons do perform coherent, real-space THz oscillations in suitably designed space charge potentials, if the kinetic energy is restricted (by the choice of the potential depth) below threshold for intervalley scattering. Oscillations have been detected by femtosecond pump and probe spectroscopy and electro-optic sampling in V-shaped as well as in parabolic potentials. A complete calculation of the observed optical signal is in good agreement with the experimental findings.