  We study spin transport in forward and reverse biased junctions between a
ferromagnetic metal and a degenerate semiconductor with a delta-doped layer
near the interface at relatively low temperatures. We show that spin
polarization of electrons in the semiconductor, Pn, near the interface
increases both with the forward and reverse current and reaches saturation at
certain relatively large current while the spin injection coefficient, Gamma,
increases with reverse current and decreases with the forward current. We
analyze the condition for efficient spin polarization of electrons in
degenerate semiconductor near interface with ferromagnet. We compare the
accumulation of spin polarized electrons in degenerate semiconductors at low
temperatures with that in nondegenerate semiconductors at relatively high, room
temperatures.
