Effect of silicon crystal structure on spin transmission through spin electronic devices

Abstract

Spin injection into and spin transport through silicon spacer layers in iron/silicon/cobalt structures has been investigated. Ultrahigh vacuum evaporated silicon spacers of varying crystal quality from amorphous to epitaxial of thicknesses from 10 to 200 Å were shown to improve their electrical conduction with increasing crystallinity, but no spin dependent transport was observed through the structure. Silicon and iron interdiffusion was also observed at the interfacial region. Device quality silicon was studied using 460 and 540 μm doped silicon wafers of resistivity 0.1 and 1 Ω cm, respectively, polished on both sides, onto which were deposited iron and cobalt layers. Sharp metal-semiconductor interfaces were achieved in this way, but no spin dependent transport, putting an upper limit on the spin diffusion length in device quality silicon wafers.