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Molecular Beam Epitaxy of Wurtzite (Ga,Mn)N Films on Sapphire(0001) Showing the Ferromagnetic Behaviour at Room Temperature

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 Added by Ken-ichi Suga
 Publication date 2001
  fields Physics
and research's language is English
 Authors S.Sonoda




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Wurtzite (Ga,Mn)N films showing ferromagnetic behaviour at room temperature were successfully grown on sapphire(0001) substrates by molecular beam epitaxy using ammonia as nitrogen source. Magnetization measurements were carried out by a superconducting quantum interference device at the temperatures between 1.8K and 300K with magnetic field applied parallel to the film plane up to 7T. The magnetic-field dependence of magnetization of a (Ga,Mn)N film at 300K were ferromagnetic, while a GaN film showed Pauli paramagnetism like behaviour. The Curie temperatures of a (Ga,Mn)N film was estimated as 940K.



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Hexagonal boron nitride (hBN) has been grown on sapphire substrates by ultra-high temperature molecular beam epitaxy (MBE). A wide range of substrate temperatures and boron fluxes have been explored, revealing that high crystalline quality hBN layers are grown at high substrate temperatures, $>$1600$^circ$C, and low boron fluxes, $sim1times10^{-8}$ Torr beam equivalent pressure. emph{In-situ} reflection high energy electron diffraction (RHEED) revealed the growth of hBN layers with $60^circ$ rotational symmetry and the $[11bar20]$ axis of hBN parallel to the $[1bar100]$ axis of the sapphire substrate. Unlike the rough, polycrystalline films previously reported, atomic force microscopy (AFM) and transmission electron microscopy (TEM) characterization of these films demonstrate smooth, layered, few-nanometer hBN films on a nitridated sapphire substrate. This demonstration of high-quality hBN growth by MBE is a step towards its integration into existing epitaxial growth platforms, applications, and technologies.
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