Synthesis of epitaxial films of Fe{sub 3}O{sub 4} and {alpha}-Fe{sub 2}O{sub 3} with various low-index orientations by oxygen-plasma-assisted molecular beam epitaxy
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
Epitaxial thin films of pure-phase Fe{sub 3}O{sub 4}(110), Fe{sub 3}O{sub 4}(111), {alpha}-Fe{sub 2}O{sub 3}(11{bar 2}0), and {alpha}-Fe{sub 2}O{sub 3}(1{bar 1}02) have been grown on MgO(110), {alpha}-Al{sub 2}O{sub 3}(0001), {alpha}-Al{sub 2}O{sub 3}(11{bar 2}0), and {alpha}-Al{sub 2}O{sub 3}(1{bar 1}02) substrates, respectively, by molecular beam epitaxy using an elemental Fe source and an electron cyclotron resonance oxygen plasma source. Characterization of the crystal structures, chemical states, and epitaxial relationships was carried out using a variety of techniques, including {ital in situ} reflection high-energy electron diffraction (RHEED), low-energy electron diffraction, x-ray photoelectron spectroscopy/diffraction, and {ital ex situ} x-ray reflectivity and diffraction. Real-time RHEED reveals that Fe{sub 3}O{sub 4} growth on MgO appears in a step-flow fashion, whereas the growth of Fe{sub 3}O{sub 4}(111) on {alpha}-Al{sub 2}O{sub 3}(0001) occurs initially by island formation, and then island coalescence. However, the growth of {alpha}-Fe{sub 2}O{sub 3} on {alpha}-Al{sub 2}O{sub 3} appears to follow an intermediate growth mode. The formation of pure-phase films is controlled largely by oxygen partial pressure, plasma power, and growth rate, but appears to be independent of growth temperature, at least from 250 to 550{degree}C. The present study demonstrates that selective growth of pure-phase iron oxides with various low-index orientations can be achieved by controlling the growth conditions and selecting suitable substrates. {copyright} {ital 1997 American Vacuum Society.}
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 467286
- Journal Information:
- Journal of Vacuum Science and Technology, A, Vol. 15, Issue 2; Other Information: PBD: Mar 1997
- Country of Publication:
- United States
- Language:
- English
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