Initial stages of growth of iron on silicon for spin injection through Schottky barrier

Abstract

The characterization of ferromagnet‐semiconductor interfaces with monolayer (ML) depth resolution is an important issue in the development of spin injection devices. In this article, highly resolved depth distributions of Fe have been measured during the initial stages of growth of Fe on Si (100) at room temperature by in situ high‐resolution Rutherford backscattering spectrometry. Extensive in‐diffusion of Fe has been observed even for the coverage of 0.0325 ML of Fe. At this coverage the Si crystal structure is apparently still conserved. Every second Si layer is depleted of Fe, thus giving rise to compositional oscillations of Fe. At higher coverages strong interdiffusion occurs resulting in the formation of silicides at the interface. Even at 9.2 ML of Fe coverage, no pure Fe layers were observed.

Tunnel Contacts for Spin Injection into Silicon: The Si-Co Interface with and without a MgO Tunnel Barrier—A Study by High-Resolution Rutherford Backscattering

“…This is similar to the model for the diffusion microstructure of Ni in Si (100) by Chang and Erskine [28] and the distribution of metal atoms in metal alloys like Cu 3 Au [29] close to the surface. A similar behaviour is also observed for the growth of Fe on Si (100) at very low coverage at room temperature [30]. Again such a configuration is stabilized by the minimization of the Gibbs-free energy, consisting of atomic binding, strain and surface energies, and the entropy of mixing.…”