Fabrication of Epitaxial FeO Film on a Si(111) Substrate.

The application of magnetic oxides in spintronics has recently attracted much attention. The epitaxial growth of magnetic oxide on Si could be the first step of new functional spintronics devices with semiconductors. However, epitaxial spinel ferrite films are generally grown on oxide substrates, not on semiconductors. To combine oxide spintronics and semiconductor technology, we fabricated FeO films through epitaxial growth on a Si(111) substrate by inserting a γ-AlO buffer layer. Both of γ-AlO and FeO layer grew epitaxially on Si and the films exhibited the magnetic and electronic properties as same as bulk. Furthermore, we also found the buffer layer dependence of crystal structure of FeO by X-ray diffraction and high-resolution transmission electron microscope. The FeO films on an amorphous-AlO buffer layer grown at room temperature grew uniaxially in the (111) orientation and had a textured structure in the plane. When FeO was deposited on Si(111) directly, the poly-crystal FeO films were obtained due to SiO on Si substrate. The epitaxial FeO layer on Si substrates enable us the integration of highly functional spintoronic devices with Si technology.