35% magnetocurrent with spin transport through Si

Efficient injection of spin-polarized electrons into the conduction band of silicon is limited by the formation of a silicide at the ferromagnetic metal (FM)/silicon interface. In the present work, this "magnetically dead" silicide (where strong spin scattering significantly reduces injected spin polarization) is eliminated by moving the FM in the spin injector from the tunnel junction base anode to the emitter cathode and away from the silicon surface. This results in over an order-of-magnitude increase in spin injection efficiency, from a previously reported magnetocurrent ratio of approximate to 2% to approximate to 35% and an estimated spin polarization in Si from approximate to 1% to at least approximate to 15%. The injector tunnel junction bias dependence of this spin transport signal is also measured, demonstrating the importance of low bias voltage to preserve high injected spin polarization. (c) 2007 American Institute of Physics.