Strongly bias-dependent spin injection from Fe into n-type GaAs

We report electrical spin injection into an n-doped GaAs (N-d=1x10(18) cm(-3)) region from an Fe thin film grown by molecular beam epitaxy. The spins are injected through an n-Al0.1Ga0.9As Schottky barrier on a spin light emitting diode. Spin injection is detected optically via carrier recombination in the layer immediately adjacent to the Schottky barrier, allowing the spin transport to be studied through this important region of interest. A pronounced dependence of injected spin polarization upon applied bias voltage reveals that efficient spin injection occurs across a range of similar to 1 V, dropping off sharply to zero at all temperatures. At bias voltages higher than that at which the maximum spin injection occurs, the Schottky barrier resistance is lowered, accompanied by hot electron spin transport in the semiconductor.