Growth of epitaxial ferromagnetic thin films on semiconductor substrates and their applications

外延生长技术的最新进展使制备各种由不同材料组成的新型人工薄膜和异质结(HS)成为可能。其中，稳定的外延铁磁/半导体HS为基础和应用研究提供了前所未有的机会，为材料设计增加了新的自由度。我们对这种新型异质结的外延生长和物理性质进行了一系列的研究，重点研究了铁磁性化合物/半导体系统。在这里，我们同时使用硅和砷化镓作为半导体闪锌矿。利用分子束外延技术，在GaAs(001)和(111)B以及Si(001)和(111)衬底上成功地生长了外延铁磁薄膜。我们原来的模板方法被发现是非常有效的在这种异质外延中获得高质量的外延薄膜，并控制铁磁性薄膜的磁各向异性。此外，我们还利用分子束外延技术在GaAs(111)B和S(111)衬底上成功地生长了MnS/GaAs/MnAs铁磁-半导体三层异质结。这些新的高速超导材料有望应用于磁性非挥发存储器件和/或与衬底Si和/或III-V半导体电子/光路耦合的磁场传感器。

Recent progressf epitxial growth technology has made it possible to prepare a variety of new artificial thin films and heterostructures (HS's) consisting of dissimilar materials. Among them, stable epitaxial ferromagnet/semiconductor HS's offer unprecedented opportunities for basic and applied research, adding a new degree of freedom inmaterials design. We have performed a series of studies on epitaxial growth and physical properties of such novel dissimilar heterostructures with focus on ferromagnetic compound/semiconductor systems. Here we used both Si and GaAs as semiconductor saubstrates. We have successfully grown epitaxial ferromagnetic MnAs thin films on GaAs (001) and (111) B,and on Si (001) and (111) substrates, by using molecular beam epitaxy (MBE). Our original template approaches are found to be very effective to obtain high-quality epitaxial films in such heteroepitaxy of dissimilar materials, and also to control magnetic anisotropy of the ferromagnetic films. Furthermore, we have successfully grown MnAs/GaAs/MnAs ferromagnet-semiconductor trilayr heterostructures on GaAs (111) B and S (111) substrates by MBE.These new HSs are promising for future applications to magnetic nonvolitile memory devices and/or magnetic field sensors coupled with underlying Si and/or III-V semiconducror electronic/optical circuitry.