Spin accumulation in degenerate semiconductors near modified Schottky contact with ferromagnets : Spin injection and extraction

We study spin transport in forward and reverse biased junctions between a ferromagnetic metal and a degenerate semiconductor with a $\ensuremath{\delta}$-doped layer near the interface at relatively low temperatures. We show that spin polarization of electrons in the semiconductor, ${P}_{n}$, near the interface increases both with the forward and reverse current and reaches saturation at certain relatively large current while the spin injection coefficient, $\ensuremath{\Gamma}$, 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.