Spin injection studies on thin film Fe/MgO/Si tunneling devices

We report progress on the injection of spin polarized electrons into 35 nm thick Si films, using Fe/MgO injector/tunnel barrier structures grown by molecular beam epitaxy on SIMOX silicon-on-insulator substrates. The device requires heavy top-surface n-type doping of the Si film to produce a suitable tunnel barrier, accomplished by diffusion from a spin-on phosphorous-doped glass. Measurements indicate a roughly exponential doping profile with 7E20 per cubic cm at the top surface and a 2 nm decay length. Three terminal measurements showed evidence of spin injection similar to reports of Jansen et al. [1], while injection with a thinner MgO barrier shows more complicated behavior. On-going measurements and modeling will be discussed.\\[4pt] [1] R. Jansen et al.; Nature 462; 491 (2009) Funding for this research was provided by the Center for Emergent Materials at the Ohio State University, an NSF MRSEC (Award Number DMR-0820414).