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Title: Epitaxial polymorphism of La{sub 2}O{sub 3} on Si(111) studied by in situ x-ray diffraction

The phase formation of La{sub 2}O{sub 3} epitaxial films during growth on Si(111) is investigated by synchrotron-based in situ grazing incidence x-ray diffraction and high resolution transmission electron microscopy. We find that first a 2–4 nm thick cubic bixbyite La{sub 2}O{sub 3} layer grows at the interface to Si(111) substrate, followed by a hexagonal La{sub 2}O{sub 3} film. Hence, to keep a cubic on cubic heteroepitaxy and to achieve high quality epitaxial nanostructures or multi-layers, the thickness of the interfacial La{sub 2}O{sub 3} layer has to be restricted to 2 nm. The larger formation energy of the cubic phase can only partially be compensated by the biaxial strain in the epitaxial film based on density functional perturbation theory. Hence, the stabilization of the cubic phase is not due to bulk strain but could be related to a lower surface or interface free energy, or to kinetic effects.
Authors:
; ; ; ; ; ;  [1]
  1. Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5–7, 10117 Berlin (Germany)
Publication Date:
OSTI Identifier:
22311067
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 2; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRYSTAL GROWTH; DENSITY FUNCTIONAL METHOD; FILMS; FORMATION HEAT; INTERFACES; LANTHANUM OXIDES; LAYERS; NANOSTRUCTURES; PERTURBATION THEORY; RESOLUTION; SILICON; STABILIZATION; STRAINS; SUBSTRATES; SURFACES; SYNCHROTRON RADIATION; THICKNESS; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION