Complete spin extraction from semiconductors near ferromagnet-semiconductor interfaces

We show that spin polarization of electrons in nonmagnetic semiconductors near specially tailored ferromagnet-semiconductor junctions can achieve 100%. This effect is realized even at moderate spin injection coefficients of the contact when these coefficie nts only weakly depend on the current. The effect of complete spin extraction occurs at relatively strong electric fields and arises from a reduction of spin penetration length due to the drift of electrons from a semiconductor towards the spin-selective tunnel junction.