Epitaxial growth of magnetic semiconductor EuO on silicon by molecular beam epitaxy.

Functional oxides demonstrate a wide range of magnetic, optical and transport properties. Their integration with silicon promises significant advances in electronics. An important key in enabling brand-new oxide technologies is the utilization of silicon/oxide epitaxy, thus making quality of the interface a critical issue. The progress depends on our ability to avoid formation of impurity phases at the interface and to tackle structural mismatch of the oxide and Si. We design a novel chemical protection of Si (001) surface on the submonolayer scale based on the surface metal silicide with the (1×5) reconstruction. This new technique is applied to the long-standing problem of integration of a ferromagnetic semiconductor with Si. Direct epitaxial growth of EuO on Si without any buffer layer, so far inaccessible, is achieved by molecular beam epitaxy. The nucleation step, comprising first 10 monolayers of EuO, is followed by a distillation-controlled growth. An alternative to standard capping procedures for EuO, based on controlled formation of an amorphous Eu2O3 layer, is devised. Crystal perfection of the films is established ex situ by x-ray diffraction and Rutherford backscattering. Magnetic properties of the EuO films match those of the bulk. [ABSTRACT FROM AUTHOR]