Electrical spin injection into moderately doped silicon enabled by tailored interfaces

Whereas spin injection from a ferromagnet into heavily doped Si is facilitated by tunneling through a narrow depletion region, it is shown here that for moderately doped Si it is crucial to suppress the Schottky barrier. Reducing carrier depletion by exposing the Si surface to a Cs flux prior to Al2O3 tunnel barrier growth, we demonstrate spin injection by tunneling from Fe into Si (confirmed by circular polarized electroluminescence) and achieve electrical detection (via the Hanle effect) of spin accumulation induced at room temperature in Ni80Fe20/Al2O3/Si junctions with 1.5 x 1018 cm(-3) carrier density. Tailored interfaces thus enable spin injection into moderately doped Si.