Structural depth profiling of iron oxide thin films using grazing incidence asymmetric Bragg x-ray diffraction

Journal Article · Thu Jun 15 04:00:00 EDT 1989 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.343230· OSTI ID:6336898

Toney, M F; Brennan, S

X-ray depth profiling in a grazing incidence asymmetric Bragg geometry is used to obtain the depth-dependent structure of a nominally ..gamma..-Fe/sub 2/O/sub 3/ thin film, which was oxidized from an Fe/sub 3/O/sub 4/ film. As the incidence angle is varied from angles less than the critical angle for total external reflection to angles greater than the critical angle, the x-ray penetration depth increases from about 20 to several thousand angstroms. The observed diffraction originates from this region of variable depth and a structural depth profile of the thin film can be obtained by measuring the diffraction pattern as a function of incidence angle. The iron oxide film is found to have a 45-A-thick surface layer of ..cap alpha..-Fe/sub 2/O/sub 3/; beneath this layer the film is predominantly ..gamma..-Fe/sub 2/O/sub 3/ but also contains about 2.6 at. % ..cap alpha..-Fe/sub 2/O/sub 3/. These data, together with previous chemical and magnetic data, suggest that during oxidation of the Fe/sub 3/O/sub 4/ film the surface layer forms by the outward diffusion of Fe ions and their subsequent oxidization to ..cap alpha..-Fe/sub 2/O/sub 3/. One possible explanation of the 2.6% ..cap alpha..-Fe/sub 2/O/sub 3/ in the bulk of the film is that the Fe/sub 3/O/sub 4/ film contains small nuclei of material that are structurally similar to ..cap alpha..-Fe/sub 2/O/sub 3/. During the oxidation to form ..gamma..-Fe/sub 2/O/sub 3/, these then grow to form small grains of ..cap alpha..-Fe/sub 2/O/sub 3/ that are observed.

• Research Organization: IBM Research Division, IBM Almaden Research Center, San Jose, California 95120
• OSTI ID: 6336898
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 65:12; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
BRAGG REFLECTION
CHALCOGENIDES
CHARGED PARTICLES
CHEMICAL REACTIONS
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIFFRACTION
DIFFUSION
FILMS
INCIDENCE ANGLE
IONS
IRON COMPOUNDS
IRON IONS
IRON OXIDES
OXIDATION
OXIDES
OXYGEN COMPOUNDS
REFLECTION
SCATTERING
THIN FILMS
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION