Growth of Fe nanocrystals on LaAlO3 (001) and epitaxial relationship determination by RHEED and XPS

Abstract

AbstractNon‐volatiles flash memories embedding nanocrystals are promising devices. These memories are made of semiconducting or metallic nanostructures inserted in an insulating matrix. SiO2, traditionally used as an insulator, is gradually replaced by high‐dielectric materials called “high‐k” oxides, to reduce leakage currents. In this context, we used a crystalline lanthanum aluminate (LaAlO3) oxide. The magnetic properties of nanoparticles of Fe can increase the storage capacity in the memories compared to the semiconductor nanostructures as Si or Ge. Memories combining these two materials require complex monolithic structures such as “LaAlO3/Fe/LaAlO3/Si(001)”. In this context we have studied the initial growth of Fe on a solid substrate of LaAlO3 (001). Fe deposits were performed by molecular beam epitaxy (MBE) at different substrate temperatures. Chemical and structural properties were investigated by X‐ray photoelectron spectroscopy (XPS) and reflection high‐energy electron diffraction (RHEED). The temperature dependence study indicates that the growth of Fe on LaAlO3 is epitaxial with a single epitaxial relationship in a tight temperature window around 500 °C. The plane (001) of Fe is parallel with the LaAlO3(001) surface, but the iron unit cell is rotated of 45° around the growth direction compared with the substrate one (<100>Fe // <110>LaAlO3). This configuration minimizes the elastic strain of the Fe which grow with the Volmer‐Weber mode. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)