Electrical spin injection into Si(001) through a SiO2 tunnel barrier

We demonstrate spin polarized tunneling from Fe through a SiO2 tunnel barrier into a Si n-i-p heterostructure. Transport measurements indicate that single step tunneling is the dominant transport mechanism. The circular polarization P-circ of the electroluminescence shows that the tunneling spin polarization reflects Fe majority spin. P-circ tracks the Fe magnetization, confirming that the spin-polarized electrons radiatively recombining in the Si originate from the Fe. A rate equation analysis provides a lower bound of 30% for the electron spin polarization in the Si at 5 K. (C) 2009 American Institute of Physics. [doi:10.1063/1.32542280]