Complete spin polarization of degenerate electrons in semiconductors near ferromagnetic contacts

We show that spin polarization of electron density in nonmagnetic degenerate semiconductors can achieve 100%. This effect is realized in ferromagnet-semiconductor FM −n + -n junctions even at moderate spin selectivity of the FM − n + contact when the electrons are extracted from the heavily doped n + −semiconductor into the ferromagnet. We derived a general equation relating spin polarization of the current to that of the electron density in nonmagnetic semiconductors. We found that the effect of the complete spin polarization is achieved near n + -n interface when an effective diffusion coefficient goes to zero in this region while the diffusion current remains finite.