Molecular Beam Epitaxy

20Ferromagnet/Semiconductor Heterostructures and Nanostructures Grown by Molecular Beam Epitaxy

Masaaki Tanaka

Center for Spintronics Research Network (CSRN), The University of Tokyo, 7‐3‐1 Hongo, Bunkyo, Tokyo, 113‐8656, Japan

Department of Electrical Engineering and Information Systems, The University of Tokyo, 7‐3‐1 Hongo, Bunkyo, Tokyo, 113‐8656, Japan

Institute for Nano Quantum Information Electronics, The University of Tokyo, 7‐3‐1 Hongo, Bunkyo, Tokyo, 113‐8656, Japan

20.1 Introduction

Introducing magnetic or spin‐related functions into semiconductor materials and optical/electronic devices is a new challenge for researchers in the field of solid‐state physics and electronic engineering [1,2]. For building “semiconductor spintronics,” one of the most important issues is the development of ferromagnet/semiconductor hybrid structures, in which we can use the spin degree of freedom. Since magnetic materials are usually dissimilar to semiconductors, integration of magnetic or spin‐related functions with semiconductor electronics has been considered difficult. However, advanced fabrication technologies, especially molecular beam epitaxy (MBE), offer new opportunities to explore in this direction, because they have made it possible to fabricate epitaxial hybrid structures having properties of both semiconductors and magnetic materials. Among them are ferromagnet/semiconductor heterostructures [3–6], ferromagnetic alloy semiconductors [7–10], and ferromagnet/semiconductor hybrid nanocluster ...