  We develop a theory of spin-dependent phenomena in the streaming regime
characterized by ballistic acceleration of electrons in the moderate electric
field until they achieve the optical phonon energy and abruptly emit the
phonons. It is shown that the Dyakonov-Perel spin relaxation is drastically
modified in this regime, the current-induced spin orientation remarkably
increases, reaches a high value ~2% in the electric field ~1kV/cm and falls
with the further increase in the field. The spin polarization enhancement is
caused by squeezing of the electron momentum distribution in the direction of
drift. We also predict field-induced oscillatory dynamics of spin polarization
of the photocarriers excited into the conduction band by a short
circularly-polarized optical pulse.
