Spin transport and spin accumulation signals in Si studied in tunnel junctions with a Fe/Mg ferromagnetic multilayer and an amorphous SiO_xN_y tunnel barrier

摘要

We studied the spin accumulation signals in phosphorus-doped n(+)-Si (8 x 10(19) cm(-3)) by measuring the spin transport in three-terminal vertical devices with Fe(3 nm)/Mg(0 and 1 nm)/SiOxNy (1 nm)/ n(+)-Si(001) tunnel junctions, where the amorphous SiOxNy layer was formed by oxnitridation of the Si substrate with radio frequency plasma. Obvious spin accumulation signals were observed at 4-300 K in the spin extraction geometry when the thickness of the Mg insertion layer was 1 nm. We found that by inserting a thin (1 nm) Mg layer, intermixing of Fe and SiOxNy is suppressed, leading to the appearance of the spin accumulation signals, and this result is consistent with the dead layer model recently proposed by our group [S. Sato et a/., Appl. Phys. Lett. 107, 032407 (2015)]. We obtained relatively high spin polarization (P-s) of electrons tunneling through the junction and long spin lifetime (tau(s)): P-s = 16% and tau(s) = 5.6ns at 4K and P-s = 7.5% and tau(s) = 2.7 ns at 300K. Tunnel junctions with an amorphous SiOxNy tunnel barrier are very promising for Si-based spintronic devices, since they can be formed by the method compatible with the silicon complementary metal-oxide-semiconductor technology. Published by AIP Publishing.